Integrated process for simultaneous preparation of alkali metal methoxides

Abstract

In a first aspect, the present invention relates to an integrated process for simultaneously preparing n mixtures P(i) comprising alkali metal methoxide and methanol, the process comprising preparing the one or more alkali metal methoxides in n reactive distillation column K(i) under reactive distillation conditions from n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streams W(i) comprising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further comprising preparing at least three streams G, T(1a) and T(1b) from a vapor phase V from the top of a rectification column D, wherein at least a part of the stream T(1a) is passed as a heating medium through an intermediate reboiler V(1a) of the rectification column D, obtaining a stream TC(1a), and at least a part of the stream T(1b) is passed as a heating medium through a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b), wherein one or more of at least a part of one or more of the top streams W(i), at least a part of the stream TC(1a), and at least a part of the stream TC(1b) are fed (back) into the rectification column D. In a second aspect, the invention relates to a chemical production unit for carrying out the process according to the first aspect; and a third aspect of the invention is related to the Use of the chemical production unit according to the second aspect or of the process according to the first aspect for simultaneously producing n mixtures P(i) comprising alkali metal methoxide and methanol.

Description

[0001]Integrated process for simultaneous preparation of alkali metal methoxides In a first aspect, the present invention relates to an integrated process for simultaneously pre- paring n mixtures P(i) comprising alkali metal methoxide and methanol, the process comprising preparing the one or more alkali metal methoxides in n reactive distillation columns K(i) under reactive distillation conditions from n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streams W(i) comprising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further com- prising preparing at least three streams G, T(1a) and T(1b) from a vapor phase V from the top of a rectification column D, wherein at least a part of the stream T(1a) is passed as a heating medium through an intermediate reboiler V(1a) of the rectification column D, obtaining a stream TC(1a), and at least a part of the stream T(1b) is passed as a heating medium through a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b), wherein one or more of at least a part of one or more of the top streams W(i), at least a part of the stream TC(1a), and at least a part of the stream TC(1b) are fed (back) into the rectification column D. In a second aspect, the invention relates to a chemical production unit for carrying out the pro- cess according to the first aspect; and a third aspect of the invention is related to the use of the chemical production unit according to the second aspect or of the process according to the first aspect for simultaneously producing n mixtures P(i) comprising alkali metal methoxide and methanol. State of the art In the prior art, processes are described wherein a mixture comprising an alkali metal alkoxide and methanol is prepared in a reactive distillation column from a methanol stream and an aque- ous stream which comprises a dissolved alkali metal hydroxide. According to these processes, the methanol stream fed into the reactive distillation column is prepared by separating methanol from water in a distillation column upstream of the reactive distillation column and using the re- spectively obtained methanol to the reactive distillation column. In this respect, reference is made, for example, to US 2002 / 0183566 A1, US 2008 / 0296786 A1, or WO 2013 / 168113 A1. However, according to the teaching of these prior art documents, only one specific mixture com- prising alkali metal methoxide and methanol could be produced. WO 2021 / 148174 A1 refers to a process for simultaneously preparing two mixtures comprising sodium metal alkoxide and potassium metal alkoxide as well as methanol, wherein a single dis- tillation column D is employed for generating a methanol stream which is then used as a metha- nol source for two parallel downstream reactive distillation columns in which the two different mixtures comprising alkali metal alkoxide and methanol are simultaneously prepared. WO 2022 / 263032 A1 also discloses a process for simultaneously preparing two mixtures com- prising alkali metal alkoxide and methanol in separate reactive distillation columns with one dis- tillation column for methanol. Therein, serial connected compressors are required for a multiple step compression of a vapor phase comprising methanol, initially taken from the rectification column, wherein the resulting multiple compressed phase is then used for providing energy to an intermediate reboiler and a bottom reboiler of the rectification column. WO 2022 / 117803 A1 discloses a process for simultaneously preparing two or more mixtures comprising alkali metal alkoxide and methanol, wherein a single distillation column D is em- ployed for generating a methanol stream which is then used, after a suitable dividing into two or more substreams, as a methanol source for two or more parallel downstream reactive distillation columns in which two or more different mixtures comprising alkali metal methoxide and metha- nol are simultaneously prepared. Therein, a part stream of a vapor phase comprising methanol and taken at the top of the rectification column D, is compressed and used as heating medium for an intermediate reboiler of the rectification column D, thus covering the energy demand of said intermediate reboiler. However, there is still a need for improvement, both in terms of energy demand and in terms of apparatus costs. Therefore, it was an object of the present invention to provide an economically advantageous process for simultaneously preparing two or more mixtures comprising alkali metal hydroxide and methanol. It was a further object of the present invention to provide a process for preparing two or more mixtures comprising alkali metal hydroxide and methanol which allows for a reduc- tion of the demand of external energy. Surprisingly, it was found that these objects can be solved by a process according to which a single rectification column is used, the intermediate reboiler and bottom reboiler thereof being provided with energy from stream(s) prepared from a vapor phase comprising methanol taken from the rectification column, using at least two compression units, wherein at least a part of a stream after having passed the first compression unit is used as heating medium for an interme- diate reboiler of the rectification column, in combination with at least a second compression unit, the stream coming therefrom being used as heating medium for a bottom reboiler of the rectifi- cation column. This approach allows a significant reduction of demand of external energy (heat- ing steam, H2Ogaseous) required for the rectification column. In a first aspect, the invention thus relates to an integrated process for simultaneously preparing n mixtures P(i) comprising alkali metal methoxide and methanol, comprising providing n reactive distillation columns K(i);providing n aqueous liquid streams H(i), a given stream H(i) comprising a dissolved alkali metalhydroxide A(i)OH, wherein n is an integer with n≥2 and i=1…n; and providing a rectification column D comprising at least one intermediate reboiler V(1a) and at least one bottom reboiler (V1b); providing a first compression unit CT(1), a second compression unit CT(2) and at least one fur- ther compression unit CG; wherein the process comprises preparing the one or more alkali metal methoxides in the n reac- tive distillation column K(i) under reactive distillation conditions from the n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streams W(i) comprising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further comprising(a) obtaining a vapor phase V comprising methanol at the top of the rectification column D,said vapor phase V having a pressure pVand a temperature TV; (b) preparing at least three streams from the vapor phase V, said at least three streams com- prising a vapor stream G having a pressure pGand a temperature TGwith pG= pVand TG= TV, and further comprising two streams T(1a) and T(1b), said stream T(1a) having a pressure pT(1a) and a temperature TT(1a) with pT(1a) > pV and TT(1a) > TV and said stream T(1b) having a pressure pT(1b) and a temperature TT(1b) with pT(1b) > pV and TT(1b) > TV,wherein for preparing the streams T(1a) and T(1b), the first compression unit CT(1) and the second compression unit CT(2) are employed;(c) preparing n streams G(i) from the vapor stream G, each of the streams G(i) having a pres-sure pG(i)and a temperature TG(i)with pG(i)> pGand TG(i)> TGfor each stream G(i), and feeding each stream G(i) into the respective reactive distillation column K(i), wherein for preparing the n streams G(i), the at least one compression unit CG is employed;(d) passing at least a part of the stream T(1a) as a heating medium through an intermediatereboiler V(1a) of the rectification column D, obtaining a stream TC(1a) having a tempera- ture TTc(1a)with TTc(1a)< TT(1a);(e) passing at least a part of the stream T(1b) as a heating medium through a bottom reboilerV(1b) of the rectification column D, obtaining a stream TC(1b) having a temperature TTc(1b)with TTc(1b) < TT(1b);(f) feeding one or more of(f.1) at least a part of one or more of the top streams W(i),(f.2) at least a part of the stream TC(1a), and(f.3) at least a part of the stream TC(1b)into the rectification column D. Feeding of at least a part of the stream TC(1a) into the rectification column D according to (f.2) is preferably done as explained in more detail herein below, and also feeding at least a part of the stream TC(1b) into the rectification column D according to (f.3) is preferably done as explained in more detail herein below. In some preferred embodiments of the process, preparing the at least three streams according to (b) comprises(b.1) splitting the vapor phase V into at least two vapor streams comprising the stream G and avapor stream T(1) having a pressure pT(1) and a temperature TT(1) with 0.95 ≤ pT(1) / pV ≤ 1.00;(b.2) preparing at least the two streams T(1a) and T(1b) from the vapor stream T(1).Preferably, at least 90 weight-%, more preferably at least 91 weight-%, more preferably at least92 weight-%, more preferably at least 93 weight-%, more preferably at least 94 weight-%, ofstream TC(1a) and / or of stream TC(1b), preferably of stream TC(1a) and of stream TC(1b), are incondensed form, based on the total weight of the respective stream being 100 weight-%. Rectification column D In some preferred embodiments of the process, the rectification column D is operated at a pres- sure at the top of D ptD in the range of from 0.5 to 10 bar(abs), preferably in the range of from 0.75 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs), more preferably in the range of from 1 to 3 bar(abs). In some preferred embodiments of the process, the rectification column D is operated at a tem-perature at the top of D TtD in the range of from 45 to 137 °C, preferably in the range of 49 to118, more preferably in the range of from 64 to 111 °C, more preferably in the range of from 64to 95°C. In some preferred embodiments of the process, the rectification column D is operated at a reflux ratio of at least 0.5:1, preferably in the range of from 0.55:1 to 1.4:1, more preferably in the range of from 0.6:1 to 1.4:1. As to the rectification column D, it is preferred that it has from 20 to 100, more preferably from 30 to 80, more preferably from 40 to 60 theoretical stages. Conceivable preferred ranges are, for example, from 40 to 50 or from 45 to 55 or from 50 to 60. Generally, the pressure at the top of the rectification column D can be chosen freely within a wide range with the proviso that the desired separation task is fulfilled. Preferably, rectification column D comprises one or more internals, preferably selected from the group consisting of tray, unstructured (random) packing, structured packing and mixtures of two or more thereof. A tray is preferably selected from the group consisting of bubble tray, sieve tray, valve tray, tunnel tray, slot tray and mixtures of two or more thereof. An unstructured pack- ing is preferably selected from the group consisting of Raschig rings, Pall rings, Berl saddles, lntalox saddles and mixtures of two or more thereof. Structured packings are sold, for example, under the trade name Mellapack® from Sulzer. In addition to the internals mentioned, other suit- able internals are known to those skilled in the art and can also be used. If structured packings or unstructured packings are contained in the rectification column, these can be divided or there can be one continuous packing. Rectification column D with top vapor recompression In some preferred embodiments of the process, the rectification column is operated with top va- por recompression. Preferably, realizing the reflux ratio comprises preparing from the vapor phase V a further vapor stream T(2), passing said stream T(2) through a condenser V(2), ob- taining a liquid stream T(3) and a waste gas stream T(2w), and feeding the liquid stream T(3) into the top of the rectification column D. Preferably, the waste gas stream T(2w) essentially consists of oxygen, nitrogen, carbon dioxide and methanol, wherein the amount of methanol in T(2w) is preferably in the range of from 2 to 80 weight-%, preferably in the range of from 10 to 30 weight-% based on the total weight of T(2w). With first and second compression units CT(1), CT(2) In some preferred embodiments of the process, (b.2) comprises splitting vapor stream T(1) into at least two streams and passing a first part stream of T(1) through the first compression unitCT(1), obtaining T(1a), and passing a second part stream of T(1) through the second compres-sion unit CT(2), obtaining T(1b). In some preferred embodiments of the process, (b.2) comprises passing vapor stream T(1)through the first compression unit CT(1), obtaining T(1a); and passing a part of T(1a) throughthe second compression unit CT(2), obtaining T(1b).The ratio of the heat flow rate of T(1a) to the heat flow rate of T(1b) f((T1a)) / f(T(1b)) is in therange of from 0 to 12, preferably in the range of from 2 to 8, more preferably in the range of from 3 to 6. Recirculation of Tc(1a) and / or Tc(1b) into D In some preferred embodiments of the process, Tc(1a) and / or Tc(1b), preferably Tc(1a) and Tc(1b), each at least partially, is / are fed to a first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depressurized form, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D. In particular in view of overall energy consumption topics, the rectification column D is operated with top vapor recompression. Reference is made, for example, to the schematic overview in Figure 1 showing a process according to the present invention with reflux. When the rectificationcolumn is operated with top vapor recompression, it is also preferred that realizing the reflux ra-tio comprises using 2 condensers, V(2) and V(3), as described below in that(i) in addition to the at least three streams G, T(1a) and T(1b), which are prepared from thevapor phase V, preparing a further stream T(2) from the vapor phase V and passing said stream T(2) through the condenser V(2), obtaining a liquid stream T(2l) and a gas stream T(2g); passing the gas stream T(2g) through the condenser V(3), obtaining a liquid stream T(2gl) and a waste gas stream T(2w); and combining the liquid streams T(2l) and (T2gl) in a second condensate drum CD(2) in depressurized form;(ii) feeding Tc(1a) and / or Tc(1b), preferably Tc(1a) and Tc(1b), each at least partially, to thefirst condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) together with stream T(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depressurized form in the second condensate drum CD(2), obtaining from said second condensate drum CD(2) a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D. Certainly, as far as step (i) above is concerned, the skilled person may also realize, if need be, said reflux ratio by using more than the 2 condensers V(2) and V(3). Preferably, Tc(1a) at least partially is fed to the first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combinedwith the liquid streams T(2l) and (T2g) in depressurized form; and Tc(1b) at least partially is fedto a third condensate drum CD(3), wherein from said third condensate drum CD(3) a gaseous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into the va- por phase V, and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into the vapor phase V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor phase V, and from said condensate drum CD(3) further a liquid stream T(5) is obtained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in depressurized form, obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D. Using a set-up with first and second compression units CT(1), CT(2) may result in that notenough stream T(1) is available for working said compression units. This can happen, for exam-ple, if the feed flows in the system are cold and the efficiency of the compressors is high. Fur- thermore, a non-sufficient steam pressure in D may result in back flow of methanol steam from V(2) into the head of D, thus disrupting the process. Using third condensation drum CD(3) with decompression of the condensate allows to have more methanol steam available for T(2), G, T(1) and / or directly in D, thus avoiding a methanol steam shortage in the process. (Fully) electrified –with CT(1), CT(2) In some preferred embodiments of the process, the n reactive columns K(i) have each a re- boiler, preferably bottom reboiler, VK(i) and wherein (e) comprises(e.1) passing at least a first part of the stream T(1b) (T(1b.1)) as a heating mediumthrough a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b.1) having a temperature TTc(1b.1) with TTc(1b.1) < TT(1b);(e.2) passing at least a second part of stream T(1b) (T(1b.2)) as a heating mediumthrough at least one bottom reboiler VK(i) of one of the n reactive distillation column K(i), obtaining a stream TC(1b.2) having a temperature TTc(1b.2)with TTc(1b.2)< TT(1b). Passing at least another part of stream T(1b) as a heating medium through all bottom reboilers VK(i) enables a process wherein no heating medium especially no hot water steam (H2Ogaseous), from other sources is required for operating D and K(i), since all thermal energy needed is gen- erated by the process itself. Only input of compression energy (electrical energy) is required. When green electricity is used, the integrated process for simultaneously preparing n mixtures P(i) comprising alkali metal methoxide and methanol can thus be carried out CO2-neutral. Preferably, stream TC(1b.2) is fed into the first condensate drum CD(1). In some preferred embodiments with two reactive distillation columns K(1) and K(2), at least a first part of T(1b.2) is passed to a bottom reboiler VK(1) of a reactive distillation column K(1) anda second part of T(1b.2) is passed to a bottom reboiler VK(2) of a reactive distillation columnK(2). Preferably, from VK(1) and VK(2) each a condensed stream is obtained, wherein these condensed streams, either separately or at least partially combined as TC(1b.2), are fed into the first condensate drum CD(1). Preferably, at least a part of Tc(1a) is fed to the first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form; and Tc(1b.1) and / or TC(1b.2), pref-erably Tc(1b.1) and TC(1b.2), at least partially is / are fed to the third condensate drum CD(3),wherein from said third condensate drum CD(3), the gaseous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into vapor stream V and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into vapor stream V or into the stream G or into the stream T(1), more preferably into the top of the rectifi- cation column D or into the vapor stream V, and from said third condensate drum CD(3) further the liquid stream T(5) is obtained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in depressurized form, thereby obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D. Having only CD(1), CD(2) results in a ratio f of the mass flow rate of stream T(1) to the mass flow rate of stream T(2) f(T(1)) / f(T(2)) > 2000. This, as indicated above, can result in non-suffi- cient methanol steam pressure in D, which in turn may result in back flow of methanol steam from V(2) into the head of D, thus disrupting the process. Using additionally the third condensa- tion drum CD(3) with decompression of the condensate allows to have more methanol steam available for the vapor stream V and / or for the stream G and / or for stream T(1) and / or directly in D, thus avoiding a methanol steam shortage in the process. Preferably, f(T(1)) / f(T(2)) when the third condensation drum CD(3) is used is < 1000, preferably < 500, more preferably < 200. With trans alcoholizationIn some preferred embodiments of the process, at least one of the n bottoms streams P(i) com-prising alkali metal methoxide A(i)OMe and methanol is at least partially fed to a trans alcoholi- sation unit TAU, wherein(x) the (part)stream comprising alkali metal methoxide A(i)OMe and methanol is contacted inthe trans alcoholisation unit TAU with an alcohol HOX, wherein X represents an alkyl resi-due selected from the group consisting of C2 to C10 alkyl, preferably C2 alkyl, thereby ob- taining a stream S(1) comprising alkali metal alkoxide A(i)OX and alcohol XOH and a stream S(2) comprising methanol;(y) removing the stream S(2) comprising methanol from the trans alcoholisation unit TAU,preferably as a liquid stream, more preferably as a liquid top stream; and removing the stream S(1) comprising alkali metal alkoxide A(i)OX and alcohol XOH from the trans alco- holisation unit TAU, preferably as a liquid stream, more preferably as a liquid stream from the lower part of TAU, more preferably as a liquid bottoms stream.Preferably, the liquid stream S(2) is obtained in that a gaseous stream S(O) is obtained withinTAU, which is condensed within TAU, more preferably using an internal condenser.Alternatively preferred, the liquid stream S(2) is obtained in that a gaseous stream S(O) is re-moved from the upper part of TAU, more preferably from the top of TAU and passed through at least one heat exchanger; thereby obtaining from the heat exchanger at least one, preferably liquid, stream S(2) comprising methanol; wherein preferably at least a part of stream S(2) is re- introduced into TAU, preferably in the upper part of TAU, preferably at a feeding point TAU(S(2)).Preferably, at least 90 volume-%, more preferably at least 95 volume-%, of stream S(2) are rein-troduced into TAU at feeding point TAU(S(2)), wherein preferably, at least a stream S(2.a) com- prising methanol is removed from TAU at a position TAU(S(2a)), wherein TAU(S(2a)) is located below TAU(S(2)). In some preferred embodiments, the stream S(2), at least partially, and / or the stream S(2.a) at least partially, is fed to the rectification column D, either separately or combined with stream M, and / or fed to the reactive distillation column K(i), either separately or combined with stream M(i). Preferably, the trans alcoholisation unit TAU has a reboiler, more preferably bottom reboiler, VTAU.1st option – three parts of T(1b)In some preferred embodiments of the process, (e) comprises(e.1) passing at least a first part of the stream T(1b) (T(1b.1)) as a heating mediumthrough a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b.1) having a temperature TTc(1b.1) with TTc(1b.1) < TT(1b);(e.2) passing at least a second part of stream T(1b) (T(1b.2))as a heating medium through at least one bottom reboiler VK(i) of one of the n reac- tive distillation column K(i), obtaining a stream TC(1b.2) having a temperature TTc(1b.2) with TTc(1b.2) < TT(1b),(e.3) passing at least a third part of stream T(1b) (T(1b.3)) as a heating medium throughthe bottom reboiler VTAU of the trans alcoholisation unit TAU, obtaining a streamTC(1b.3) having a temperature TTc(1b.3) with TTc(1b.x) < TT(1b).Preferably, the stream TC(1b.3) is fed into the first condensate drum CD(1).In some preferred embodiments of the process, at least a part of Tc(1a) is fed to the first con-densate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) andsaid liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurizedform; and TC(1b.1) and / or TC(1b.2), and / or TC(1b.3), preferably TC(1b.1) and TC(1b.2) and TC(1b.3), at least partially is / are fed to the third condensate drum CD(3), wherein from said third condensate drum CD(3), the gaseous stream T(4) is obtained, which is fed into the top of the rectificationcolumn D and / or into vapor stream V and / or into the stream G and / or into the stream T(1), pref-erably into the top of the rectification column D or into vapor stream V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor stream V, and from said third condensate drum CD(3) further the liquid stream T(5) is obtained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in depressurized form, thereby obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D. 2nd option –T(1b) split into T(1b.1) and T(1b.2), T(1b.2) split further into T(1b.2.1) and T(1b.2.2)In some preferred embodiments of the process, (e) comprises(e.1) passing at least a first part of the stream T(1b) (T(1b.1)) as a heating mediumthrough a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b.1) having a temperature TTc(1b.1)with TTc(1b.1)< TT(1b);(e.2.1) splitting a second part of stream T(1b) (T(1b.2)) into at least two sub-streams(T(1b.2.1)) and (T(1b.2.2);(e.2.2) passing at least sub-stream (T(1b.2.1)) as a heating medium through at least onebottom reboiler VK(i) of one of the n reactive distillation column K(i), obtaining astream TC(1b.2.1) having a temperature TTc(1b.2) with TTc(1b.2.1) < TT(1b);(e.2.3) passing at least subs-stream (T(1b.2.2)) as a heating medium through the bottomreboiler VTAU of the trans alcoholisation unit TAU, obtaining a stream TC(1b.2.2) hav- ing a temperature TTc(1b.2.2) with TTc(1b.2.2) < TT(1b). Preferably, stream TC(1b.2.2) is fed into the first condensate drum CD(1). In some preferred embodiments of the process, at least a part of Tc(1a) is fed to the first con- densate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form; and TC(1b.1) and / or TC(1b.2.1), and / or TC(1b.2.2), preferably TC(1b.1) and TC(1b.2.1) and TC(1b.2.2), at least partially is / are fed to the third condensate drum CD(3), wherein from said third conden- sate drum CD(3), the gaseous stream T(4) is obtained, which is fed into the top of the rectifica- tion column D and / or into vapor stream V and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into vapor stream V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the va- por stream V, and from said third condensate drum CD(3) further the liquid stream T(5) is ob-tained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with theliquid streams T(2l) and (T2gl) in CD(2) in depressurized form, thereby obtaining a combinedliquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into thetop of the rectification column D. 3rd option –parts of T(1a) In some preferred embodiments of the process, (d) comprises(d.1) passing at least a first part of the stream T(1a) (T1a.1) as a heating medium throughan intermediate reboiler V(1a) of the rectification column D, obtaining a stream TC(1a.1) having a temperature TTc(1a.1)with TTc(1a.1)< TT(1a.1);(d.2) passing at least a second part of stream T(1a) (T(1a.2)) as a heating mediumthrough the bottom reboiler VTAUof the trans alcoholisation unit TAU, obtaining a stream TC(1a.2) having a temperature TTc(1a.2)with TTc(1a.2)< TT(1a).Preferably, stream TC(1a.2) is fed into the first condensate drum CD(1).In some preferred embodiments of the process, at least a part of Tc(1a.1) and Tc(1a.2) at leastpartially are fed to the first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form; and Tc(1b.1) and / or TC(1b.2), preferably Tc(1b.1) and TC(1b.2), at least partially is / are fed to the third condensate drum CD(3), wherein from said third condensate drum CD(3), the gaseous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into vapor stream V and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into vapor stream V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor stream V, and from said third conden- sate drum CD(3) further the liquid stream T(5) is obtained, which is fed to the second conden- sate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in depressurized form, thereby obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D. The trans alcoholisation unit TAU preferably comprises at least one reactive distillation column, which is preferably operated at a top pressure in the range of from 0.2 to 10 bar(abs), morepreferably at a top pressure in the range of from 0.5 to 3 bar (abs), more preferably at a toppressure in the range of from 0.8 to 2 bar(abs). Preferably, at a given pressure, the bottom tem- perature of TAU’s at least one reactive distillation column is selected so that the alkali metal alkoxide A(i)OX remains dissolved.For example, for XOH being ethanol and A(1)OMe being so- dium methanolate, the bottoms temperature of TAU’s at least one reactive distillation column isin the range of from 73 to 123 °C (top pressure in the range of from 0.5 to 3 bar (abs)), morepreferably in the range of from 85 to 110 °C (top pressure in the range of from 0.8 to 2 bar(abs)), and / or, preferably and, the top temperature of TAU is in the range of from 48 to 95 °C(top pressure in the range of from 0.5 to 3 bar (abs)), more preferably in the range of from 58 to83 °C (top pressure in the range of from 0.8 to 2 bar(abs)). Preferably, TAU’s at least one reac- tive distillation column comprises in the range of from 20 to 200 overall theoretical stages (OTS), more preferably in the range of from 30 to 100 overall theoretical stages (OTS). Preferably, TAU’s at least one reactive distillation column comprises fillings and / or packings and / or trays. Fillings are preferably selected from the group consisting of Raschig ring (a hollow cylinder), Pall ring, Hiflow ring and lntalox saddle, made from, for example, glass, ceramic, metal and / or plastics. Packings are preferably structured packings. Preferably, TAU comprises one or more tray(s) selected from the group consisting of sieve tray, bell tray or valve tray, tun- nel tray and Thormann® tray. Preferably, the upper part (the reinforcement part) of TAU’s at least one reactive distillation column comprises packings, and the lower part of TAU’s at least one reactive distillation column, preferably the part of TAU’s at least one reactive distillation col- umn below the feeding point of the at least one of the n bottoms streams P(i), comprises trays. Preferably, the at least one of the n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol is at least partially fed to a trans alcoholisation unit TAU’s at least one reactive distillation column at a position in the middle part of TAU’s at least one reactive distilla- tion column, preferably at a theoretical stage in the range of from 0.3 x OTS to 0.7 x OTS, more preferably in the range of from 0.4 x OTS to 0.6 x OTS, each preferably counted from the bot- tom of TAU’s at least one reactive distillation column. TAU’s at least one reactive distillation column has preferably a sump circulation; for details, ref- erence is made to WO 2021 / 122702 A1. Preferably, the steps (x), (y) as described herein above refer to TAU’s at least one reactive dis- tillation column. Further details of trans alcoholisation unit TAU and TAU’s at least one reactive distillation column respectively are as disclosed for the reactive distillation column in WO 2021 / 122702 A1. With a third compression unit CT(3) In some preferred embodiments of the process, a providing a third compression unit CT(3) isprovided, wherein (b) comprises preparing at least four streams from the vapor phase V, said atleast four streams comprising vapor stream G, stream T(1a), stream T(1b), and a further stream T(1c), said stream T(1c) having a pressure pT(1c) and a temperature TT(1c) with pT(1c) > pV and TT(1c) > TV, wherein for preparing the stream T(1c), the third compression unit CT(3) is employed. In some preferred embodiments, preparing the at least four streams according to (b) comprises splitting the vapor phase V into at least two vapor streams comprising the stream G and a vapor stream T(1) having a pressure pT(1) and a temperature TT(1) with 0.95 ≤ pT(1) / pV ≤ 1.00; and pre- paring at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1). Said pre- paring at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1) comprises in some preferred embodiments a splitting of T(1) into at least two streams; passing a first part stream of T(1) through CT(1), obtaining T(1a), and passing a second part stream of T(1) through the second compression unit CT(2), obtaining T(1b), and splitting T(1a) into at least two streams and passing a part stream of T(1a) through the third compression unit CT(3), obtaining T(1c). In some alternatively preferred embodiments, said preparing at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1) comprises splitting T(1) into at least two streams; passing a first part stream of T(1) through CT(1), obtaining T(1a), and passing a second part stream of T(1) through the third compression unit CT(3), obtaining T(1c); and splitting T(1a) into at least two streams and passing a part stream of T(1a) through the second compression unit CT(2), obtaining T(1b). In some other alternative preferred embodiments, said preparing at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1) comprises splitting vapor stream T(1) into at least three streams; passing a first part stream of T(1) through the first compression unit CT(1), obtaining T(1a), passing a second part stream of T(1) through the second compression unit CT(2), obtaining T(1b), and passing a third part stream of T(1) through the third compression unit CT(3), obtaining T(1c). In some other alternative preferred embodiments, said preparing at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1) comprises passing T(1) through the first com- pression unit CT(1), obtaining T(1a); splitting T(1a) into at least three part streams, passing a part stream of T(1a) through the second compression unit CT(2), obtaining T(1b), and passing a part stream of T(1a) through the third compression unit CT(3), obtaining T(1c). Recirculation of Tc(1a) and / or Tc(1b) into D In some preferred embodiments of the process, Tc(1a) and / or Tc(1b), preferably Tc(1a) and Tc(1b), each at least partially, is / are fed to a first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depressurized form, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D. In “depressurized form” regarding the liquid streams T(1l), T(2l) and (T2gl) and the combined stream respectively means that these streams and respectively the combined liquid stream therefrom have a pressure pcs about equal to the pressure at the top of rectification column D as described above, i.e.0.95 ≤ pcs / ptD ≤ 1.05.(Fully) electrified – with also CT(3)In some preferred embodiments of the process, the n reactive columns K(i) have each a re-boiler, preferably bottom reboiler, VK(i) and wherein at least a part of T(1c) is passed as heatingmedium through at least one bottom reboiler VK(i) of one of the n reactive distillation column K(i), obtaining a stream TC(1c) having a temperature TTc(1c)with TTc(1c)< TT(1c).In some preferred embodiments, at least a first part of T(1c) (T(1c.1) is passed to a bottom re- boiler VK(1) of a reactive distillation column K(1) and a second part of T(1c) (T(1c.2)) is passed to a bottom reboiler VK(2) of a reactive distillation column K(2). Passing at least a part of streamT(1c) as a heating medium through all bottom reboilers VK(i), enables a process wherein no heating medium especially no hot water steam (H2Ogaseous), from other sources is required for operating D and K(i), since all thermal energy needed is generated by the process itself. Only input of compression energy (electrical energy) is required. When green electricity is used, the integrated process for simultaneously preparing n mixtures P(i) comprising alkali metal methox- ide and methanol can thus be carried out CO2-neutral. In some preferred embodiments with two reactive distillation columns K(1), K(2), at least a first part of T(1c) (T(1c.1) is passed to a bot- tom reboiler VK(1) of a reactive distillation column K(1) and a second part of T(1c) (T(1c.2)) is passed to a bottom reboiler VK(2) of a reactive distillation column K(2). Preferably, from VK(1) a stream TC(1c.1) and from VK(2) a stream TC(1c.2) is / are obtained, which are then, either sepa- rately or at least partially combined as TC(1c), fed into the same (first) condensate drum CD(1), into which also Tc(1a) and / or Tc(1b) are fed. In particular in view of overall energy consumption topics, the rectification column D is operated with top vapor recompression. Reference is made, for example, to the schematic overviews in Figures 3-6 showing a process according to the present invention with reflux. When the rectifi-cation column is operated with top vapor recompression, it is also preferred that realizing the re-flux ratio comprises using 2 condensers, V(2) and V(3), as described below in that(i) in addition to the at least three streams G, T(1a) and T(1b), which are prepared from thevapor phase V, preparing a further stream T(2) from the vapor phase V and passing said stream T(2) through the condenser V(2), obtaining a liquid stream T(2l) and a gas stream T(2g); passing the gas stream T(2g) through the condenser V(3), obtaining a liquid stream T(2gl) and a waste gas stream T(2w); and combining the liquid streams T(2l) and (T2gl) in a second condensate drum CD(2) in depressurized form;(ii) feeding TC(1c), preferably with Tc(1a) and Tc(1b), each at least partially, to the first con-densate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) together with stream T(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depressurized form in the second condensate drum CD(2), ob- taining a combined liquid stream from said second condensate drum CD(2), which is fedas the stream T(3) into the top of the rectification column D. Certainly, as far as step (i) above is concerned, the skilled person may also realize, if need be, said reflux ratio by using more than the 2 condensers V(2) and V(3) or by using only one con- denser V(2). Vapor phase V In some preferred embodiments of the process, the vapor phase V has a pressure pV, in the range of from 0.5 to 10 bar(abs), preferably in the range of from 0.75 to 6 bar(abs), more prefer-ably in the range of from 1 to 5 bar(abs), more preferably in the range of from 1 to 3 bar(abs). Insome preferred embodiments of the process, the vapor phase V has a temperature TV in therange of from45 to 137 °C, preferably in the range of 49 to 118, more preferably in the range offrom 64 to 111 °C, more preferably in the range of from 64 to 95°C.Streams taken from rectification column D for heating purpose In some preferred embodiments of the process, a stream T(Di) having a temperature TT(Di) is taken from the rectification column D at an intermediate position and passed for heating pur- pose through the intermediate reboiler V(1a) of the rectification column D, obtaining a heatedstream Th(Di) having a temperature TTh(Di) with TTh(Di) > TT(Di), wherein heated stream Th(Di) is re-introduced into rectification column D; and a stream T(Db) having a temperature TT(Db) is taken from the rectification column D at a bottomposition and passed for heating purpose through the bottom reboiler V(1b) of the rectificationcolumn D, obtaining a stream Th(Db) having a temperature TTh(Db) with TTh(Db) > TT(Db), wherein heated stream Th(Db) is reintroduced into rectification column D. Heated stream Th(Di) preferably comprises two phases, i.e. a gaseous and a liquid part. Analo- gously, heated stream Th(Db) preferably comprises two phases, i.e. a gaseous and a liquid part. Stream T(Ki) In some preferred embodiments of the process, a bottom stream T(Ki) having a temperature TT(Ki)is taken from the bottom of the n reactive columns K(i) and passed for heating purpose through a bottom reboiler VK(i), thereby obtaining a heated stream Th(Ki) having a temperatureThT(Ki) and wherein ThT(Ki) > TT(Ki); wherein heated stream Th(Ki) is reintroduced into rectificationcolumn D.Stream T(1) In some preferred embodiments of the process, stream T(1) has a temperature TT(1)with 0.95 ≤ TT(1) / TV≤ 1.00 and / or a pressure pT(1)with with 0.95 ≤ pT(1) / pV≤ 1.00. Stream T(1a) In some preferred embodiments of the process, stream T(1a) has a pressure pT(1a), which is ad-justed so thatTcondT(1a) is ≥ TboilT(Di) + 3 K, wherein TcondT(1a) is the condensation temperature ofstream T(1a) at a pressure pT(1a) and TboilT(Di) is the boiling temperature of stream T(Di) at a pres-sure pT(Di). Stream T(1a) preferably has a condensation temperature TcondT(1a) which is in therange of from 3 to 30 K, preferably in the range of from 4 and 25 K, more preferably in the rangeof from 5 and 20 K, higher than TboilT(Di). Stream T(1b) In some preferred embodiments of the process, stream T(1b) has a pressure pT(1b) , which is ad-justed so that TcondT(1b) is ≥ TboilT(Db) + 3 K, wherein TcondT(1b) is the condensation temperature ofstream T(1b) at a pressure pT(1b) and TboilT(Db) is the boiling temperature of stream T(Db) at apressure pT(Db). Stream T(1b) preferably has a condensation temperature TcondT(1b) which is in therange of from 3 to 30 K, more preferably in the range of from 4 and 25 K, more preferably in therange of from 5 and 20 K, higher than TboilT(Db). Stream T(1c) In some preferred embodiments of the process, stream T(1c) has a pressure pT(1c), which is ad-justed so that TcondT(1c) is ≥ TboilT(Ki) + 3 K, wherein TcondT(1c) is the condensation temperature ofstream T(1c) at a pressure pT(1c) and Tboil T(Ki)) is the boiling temperature of stream T(Ki). StreamT(1c) preferably has a condensation temperature TcondT(1c)which is in the range of from 3 to30 K, more preferably in the range of from 4 and 25 K, more preferably in the range of from 5and 20 K, higher than TboilT(Ki). Stream T(4) In some preferred embodiments of the process, gaseous stream T(4) has a pressure pT(4)in the range of pT(1b) >pT(4) >pV..In some preferred embodiments, the process comprises(g) feeding a stream M comprising methanol into the rectification column D at a position I(M).A stream M comprising methanol is fed into the rectification column D. This stream M, also re-ferred to as fresh methanol stream M, is fed into D in order provide sufficient methanol for the overall process, in particular to compensate the loss of methanol removed from the process via the mixtures P(i). Generally, there are no specific requirements as far as the methanol content of M is concerned, and the skilled person will be in the position to choose suitable methanol streams M. Preferably, however, it is preferred that the stream M comprises only a low amount of water. Therefore, it is further preferred that from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream M consist of methanol and optionally water, wherein the amount of water comprised in the stream M is pref- erably at most 2000 weight-ppm, more preferably at most 1500 weight-ppm, more preferably at most 1000 weight-ppm, such as at most 750 weight-ppm or at most 500 weight-ppm or at most 250 weight-ppm. Generally, the stream M can be fed into the rectification column D at any suitable position. Pref- erably, the stream M is fed to the upper part of D, more preferably at least 2, 3 or 4 theoretical stages from the top of D, more preferably at least 4 theoretical stages from the top of D, more preferably between the 4thand the 20ththeoretical stage from the top of D, more preferably be- tween the 6thand the 15ththeoretical stage from the top of D, such as between the 6thand the10th theoretical stage or between to 8th and the 12th theoretical stage or between the 10th andthe 14ththeoretical stage or between to 12thand the 15ththeoretical stage. As far as the temper- ature of the stream M is concerned at which the stream M is fed into D, it is preferred that thetemperature is in the range of from ambient temperature up to the boiling point of methanol atthe column pressure of D; more preferably the temperature is ambient temperature. K(i), K(1), K(2) In some preferred embodiments, the process further comprises for at least one reactive distilla- tion column K(i), preferably for n reactive distillation columns K(i), feeding the stream G(i) into the lower part of the reactive distillation column K(i) and feeding the aqueous liquid stream H(i) into the upper part of the reactive distillation column K(i). In some preferred embodiments of the process, a stream H(1) comprises dissolved sodium hy- droxide and a stream H(2) comprises dissolved potassium hydroxide, wherein sodium methox- ide is prepared in the reactive distillation column K(1) from which the stream W(1) is obtained and potassium methoxide is prepared in the reactive distillation column K(2) from which the stream W(2) is obtained. In some preferred embodiments of the process n is 2 (n = 2). With respect to the stream G, it is preferred that said stream G comprises methanol and water, wherein more preferably from 99.95 to 100 weight-% of G consist of methanol and water, and wherein the water content of G is at most 200 weight-ppm, more preferably at most 150 weight-ppm, more preferably at most 100 weight-ppm, wherein more preferably, said water content isin the range of from 5 to 100 weight-ppm, more preferably in the range of from 10 to 100 weight- ppm, more preferably in the range of from 15 to 100 weight-ppm. According to (c), n streams G(i) are prepared from the vapor stream G, each of the streams G(i) having a pressure pG(i) and a temperature TG(i) with pG(i) > pG and TG(i) > TG for each stream G(i), and feeding each stream G(i) into the respective reactive distillation column K(i), wherein for preparing the n streams G(i), the at least one compression unit CG is employed. Preferably, the stream G is divided into the two streams G(1) and G(2), wherein the stream G has a mass flow rate f(G), the stream G(1) has a mass flow rate f(G(1)) and the stream G(2) has a mass flow rate f(G(2)), wherein f(G) = f(G(1)) + f(G(2)). Generally, the stream G can be divided by any conceivable method. Preferably (c) comprises passing the stream G into a stream dividing device S, said device more preferably comprising a pipe junction. In context, it is noted that the term “the stream is divided into two streams” refers to a method according to which the streams obtained from said dividing have the same chemical composition as the stream G. As far as the ratios f(G(1)) / f(G) and f(G(2)) / f(G) are concerned, the present invention allows for a flexible adjusting of said ratios in that the individual flow rates f(G(1)) and f(G(2)) can be chosen depending on the desiredamount of A(1)OMe, preferably sodium methoxide, to be obtained relative to the desiredamount of A(2)OMe, preferably potassium methoxide, to be obtained. Prior to dividing according to (c), the stream G can be passed through the at least one compres- sion unit CG, thereby realizing a pressure increase of G. Preferably, the pressure is suitably in- creased so that the pressure of the streams after dividing is adapted to the desired pressure when the streams are fed into the reactive distillation columns K(i) and ultimately, via the streams W(i), back into D. Preferably, said pressure increase is in the range of from 0.1 to 0.8 bar, more preferably in the range of from 0.15 to 0.6 bar, more preferably in the range of from 0.2 to 0.4 bar. According to this embodiment of the present invention, it is preferred that the di- viding according to (c) comprises passing the compressed stream G into a stream dividing de- vice S, said device preferably comprising a pipe junction and at least one control device allow-ing for adjusting the ratio f(G(1)) / f(G(2)), wherein said at least one control device is locateddownstream of said pipe junction. At least one of these control devices is located either in the stream G(1) or in the stream G(2) or in both streams G(1) and G(2), and it is preferred that the at least one control device preferably is a control valve. Afterwards, the compressed stream G is fed into the dividing device S and subsequently, the resulting streams G(1) and G(2) are fed into the reactive distillation columns K(1) and K(2) respectively. Alternatively, the pressure increase mentioned above is realized not by compressing the stream G prior to, but after dividing. In this alternative embodiment, stream G is fed to a dividing device S and divided in a stream G(1) anda stream G(2). Prior to be fed into the reactive distillation column K(1), the stream G(1) ispassed through a compression unit CG(1), thereby realizing a pressure increase of G(1) in the range of from 0.1 to 0.8 bar, preferably in the range of from 0.15 to 0.6 bar, more preferably inthe range of from 0.2 to 0.4 bar. Certainly, said compression of G(1) can be combined with apre-compression of the stream G prior to dividing; however, it is preferred that this compressing of G(1) is performed with no compression of G being performed prior to dividing. Consequently, in this alternative embodiment, it is also preferred that prior to be fed into the reactive distillation column K(2), the stream G(2) is passed through a compressor CG(2), thereby realizing a pres- sure increase of G(2) in the range of from 0.1 to 0.8 bar, preferably in the range of from 0.15 to 0.6 bar, more preferably in the range of from 0.2 to 0.4 bar. Certainly, said compression of G(2) can be combined with a pre-compression of the stream G prior to dividing; however, it is pre- ferred that this compressing of G(2) is performed with no compression of G being performed prior to dividing. As far as the stream H(1) is concerned, it is preferred that from 99 to 100 weight-%, more pref- erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream H(1) consist of A(1)OH and water, wherein more preferably from 37.5 to 58 weight-%, more preferably from 40 to 55 weight-%, more preferably from 42.5 to 52 weight-% of the stream H(1) consist of A(1)OH, preferably sodium hydroxide. Preferably the stream H(1) is fed into the reac- tive distillation column K(1) at a temperature of H(1) in the range of from ambient temperature to its boiling temperature, more preferably in the range of from 50 to 80 °C such as from 50 to 60 °C or from 60 to 70 °C or from 70 to 80 °C. Heating of the stream H(1) to this temperature may be accomplished with any suitable means such as a heat exchanger. It is preferred that the stream H(1) is fed into the top of the reactive distillation column K(1), more preferably to the first theoretical stage from the top. As to the reactive distillation column K(1), it is preferred that said column has from 5 to 50, more preferably from 10 to 40, more preferably from 15 to 30 theoretical stages, such as from 15 to 20 or from 20 to 25 or from 25 to 30 theoretical stages. Generally, the stream G(1) can be fed at any suitable position into K(1); preferably, G(1) is fed into the reactive distillation column K(1) ata position between the bottoms and the 5th theoretical stage, more preferably between the bot-toms and the 3rdtheoretical stage, more preferably between the bottoms and the 2ndtheoretical stage of the reactive distillation column K(1). Preferably, the reactive distillation column K(1) is operated at a pressure at the top in the range of from 0.5 to 10 bar(abs), more preferably in the range of from 1 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs). Suitable pre- ferred ranges are, for example, from 1 to 3 bar(abs) or from 2 to 4 bar(abs) of from 3 to 5 bar(abs). While it is generally possible to operate the reactive distillation column K(1) with reflux, it is preferred that the reactive distillation column K(1) is operated at a reflux ratio of 0:1. As far as the stream W(1) is concerned which is obtained from the top of K(1), it is preferred that from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of W(1) consist of methanol and water. More preferably, from 1 to 10 weight-%, more preferably from 2 to 8 weight-%, more preferably from 4 to 7 weight-%, more preferably from 5 to 6 weight-% of the stream W(1) consist of water. As far as the mixture P(1) is concerned, it is preferred that from 99 to 100 weight-%, more pref- erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream P(1) consist of A(1)OMe, preferably sodium methoxide, and methanol. More preferably, from 10 to 50 weight-%, more preferably from 20 to 40 weight-%, more preferably from 25 to 35 weight-% of the stream P(1) consist of A(1)OMe, preferably sodium methoxide. More preferably, at most 5000 weight-ppm, more preferably at most 2000 weight-ppm, more preferably at most 1000 weight-ppm of the stream P(1) consist of water. Conceivable maximum water contents may in- clude, for example, 750 weight-ppm or 500 weight-ppm or 250 weight-ppm. Preferably, the con- centration of A(1)OMe, preferably sodium methoxide in the stream P(1) are realized by the skilled person by operating the reactive distillation column K(1) at a respective reboiler duty. According to the present invention, it is preferred that the top of the reactive distillation column K(1) is equipped with a suitable droplet separating device D(1), preferably a demister. Thus, the process preferably comprises separating droplets comprising A(1)OH, preferably sodium hy- droxide, from the vapor stream in the top of K(1). It is further preferred that, in particular for cleaning purposes, said demister is suitably treated with a suitable stream M(1). A preferred treating may comprise, preferably consist of at least temporarily spraying the demister with the stream M(1). Regarding the chemical composition of M(1), it is especially preferred that M(1) comprises methanol, wherein it is more preferred that M(1) is branched from a condensed top stream removed from the rectification column D, for example one of the streams described above, or being a fresh methanol stream, for example a stream branched from the stream M de- scribed above. As far as the stream H(2) is concerned, it is preferred that from 99 to 100 weight-%, more pref- erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream H(2) consist of A(2)OH, preferably potassium hydroxide, and water, wherein more preferably 30 to 55 weight-%, more preferably from 40 to 52.5 weight-%, more preferably from 45 to 50 weight-% of the stream H(2) consist of A(2)OH, preferably potassium hydroxide. Preferably the stream H(2) is fed into the reactive distillation column K(2) at a temperature of H(2) in the range of from ambient temperature to its boiling temperature, more preferably in the range of from 50 to 80 °C such as from 50 to 60 °C or from 60 to 70 °C or from 70 to 80 °C. Heating of the stream H(2) to this temperature may be accomplished with any suitable means such as a heat ex- changer. It is preferred that the stream H(2) is fed into the top of the reactive distillation column K(2), more preferably to the first theoretical stage from the top. As to the reactive distillation column K(2), it is preferred that said column has from 5 to 50, more preferably from 10 to 40, more preferably from 15 to 30 theoretical stages, such as from 15 to 20 or from 20 to 25 or from 25 to 30 theoretical stages. Generally, the stream G(2) can be fed at any suitable position into K(2); preferably, G(2) is fed into the reactive distillation column K(2) at a position between the bottoms and the 5ththeoretical stage, more preferably between the bot- toms and the 3rdtheoretical stage, more preferably between the bottoms and the 2ndtheoretical stage of the reactive distillation column K(2). Preferably, the reactive distillation column K(2) is operated at a pressure at the top in the range of from 0.5 to 10 bar(abs), more preferably in the range of from 1 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs). Suitable pre- ferred ranges are, for example, from 1 to 3 bar(abs) or from 2 to 4 bar(abs) of from 3 to 5 bar(abs). While it is generally possible to operate the reactive distillation column K(2) with reflux, it is preferred that the reactive distillation column K(2) is operated at a reflux ratio of 0:1. As far as the stream W(2) is concerned which is obtained from the top of K(2), it is preferred that from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of W(2) consist of methanol and water. More preferably, from 1 to 15 weight-%, more preferably from 2 to 12 weight-%, more preferably from 6 to 10 weight-% of the stream W(2) consist of water. As far as the mixture P(2) is concerned, it is preferred that from 99 to 100 weight-%, more pref- erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream P(2)consist of A(2)OMe, preferably potassium methoxide, and methanol. More preferably, from 10to 50 weight-%, more preferably from 20 to 40 weight-%, more preferably from 25 to 35 weight- % of the stream P(2) consist of A(2)OMe, preferably potassium methoxide. More preferably, at most 5000 weight-ppm, more preferably at most 2000 weight-ppm, more preferably at most 1000 weight-ppm of the stream P(2) consist of water. Conceivable maximum water contents may include, for example, 750 weight-ppm or 500 weight-ppm or 250 weight-ppm. Preferably, the concentration of A(2)OM, preferably potassium methoxide in the stream P(2) are realized by the skilled person by operating the reactive distillation column K(2) at a respective reboiler duty.According to the present invention, it is preferred that the top of the reactive distillation columnK(2) is equipped with a suitable droplet separating device D(2), preferably a demister. Thus, the process preferably comprises separating droplets comprising A(2)OH, preferably potassium hy- droxide, from the vapor stream in the top of K(2). It is further preferred that, in particular for cleaning purposes, said demister is suitably treated with a suitable stream M(2). A preferred treating may comprise, preferably consist of at least temporarily spraying the demister with the stream M(2). Regarding the chemical composition of M(2), it is especially preferred that M(2) comprises methanol, wherein it is more preferred that M(2) is branched from a condensed top stream removed from the rectification column D, for example one of the streams describedabove, or being a fresh methanol stream, for example a stream branched from the stream M de-scribed above. In the above, it was described that according to the present invention, the stream G, prior to di- viding, is preferably passed through a compression unit CG. According to the present invention, it is also possible that either in addition to at least one of the above alternatives or, preferably as the sole respective compression, prior to being fed into the rectification column D, the stream W(1) is passed through a compressor C(1), thereby realizing a pressure increase of W(1) pref- erably in the range of from 0.1 to 0.8 bar, more preferably in the range of from 0.15 to 0.6 bar, more preferably in the range of from 0.2 to 0.4 bar, and prior to being fed into the rectification column D, the stream W(2) is passed through a compressor C(2), thereby realizing a pressure increase of W(2) in the range of from 0.1 to 0.8 bar, more preferably in the range of from 0.15 to0.6 bar, more preferably in the range of from 0.2 to 0.4 bar. According to this embodiment of thepresent invention, it is also possible to suitably combine the streams W(1) and W(2), prior to be- ing passed through a compressor, in a combining device to obtain a respective combinedstream W, and pass said combined stream W, prior to being fed into D, through a compressor,thereby realizing a pressure increase of W(1) preferably in the range of from 0.1 to 0.8 bar, more preferably in the range of from 0.15 to 0.6 bar, more preferably in the range of from 0.2 to 0.4 bar. Said combining device preferably comprises a pipe junction and at least one control de- vice, preferably a control valve. As far as the integrated process of the present invention is concerned, it is noted that for simul-taneously preparing, in addition to the 2 mixtures P(1) and P(2) as described above in detail, a3rdmixture P(3) etc. can be obtained, the skilled person, based on his general knowledge, willbe in the position to derive from said details above in a straight-forward manner also any detailadjusting the overall process. According to the present invention, it is also conceivable that from at least one of the streams P(i), A(i)OMe is at least partially separated from methanol, more preferably obtaining solid, more preferably crystalline A(i)OMe. Thus, solid, preferably crystalline sodium methoxide and solid, preferably crystalline potassium methoxide, can be obtained. Recycling of W(i) into rectification column D- Concept AGenerally, it is preferred according to the process of the present invention that at least a part of one or more of the top streams W(i) is fed into rectification column D (feature (f.1)). In some preferred embodiments of the process, feeding of the stream W(i) into the rectification column D according to (f.1) comprises(f.1.1) feeding at least a part of the top stream W(1) into the lower part of the rectificationcolumn D at a position I(1);(f.1.2) feeding at least a part of the top stream W(2) into the lower part of the rectificationcolumn D at a position I(2), wherein the position I(2) is located below the position I(1); wherein between the positions I(1) and I(2), the rectification column D is equipped with inter- nals. The rectification column D’s internals are selected from tray, unstructured (random) packing, structured packing and mixtures of two or more thereof. Preferably, rectification column D com- prises one or more internals, preferably selected from the group consisting of tray, unstructured (random) packing, structured packing and mixtures of two or more thereof. A tray is preferably selected from the group consisting of bubble tray, sieve tray, valve tray, tunnel tray, slot tray and mixtures of two or more thereof. An unstructured packing is preferably selected from the group consisting of Raschig rings, Pall rings, Berl saddles, lntalox saddles and mixtures of two or more thereof. Structured packings are sold, for example, under the trade name Mellapack® from Sul- zer. In addition to the internals mentioned, other suitable internals are known to those skilled in the art and can also be used. If structured packings or unstructured packings are contained in the rectification column, these can be divided or there can be one continuous packing. Positon I(2) is preferably located in the lower third of rectification column D and positon I(1) is also located in the lower third of rectification column D, wherein preferably in the range of from 1 to 15 preferably of from 2 to 10, more preferably of from 3 to 5, theoretical trays are present be- tween the position I(2) and I(1). The methanol concentration in stream W(1) cMeOH(1) is preferably higher than the methanol con- centration in W(2) cMeOH(2) with cMeOH(1) > cMeOH(2), so that W(1) is fed into rectification column D at a position I(1), wherein the methanol concentration at that position I(1) within the rectifica- tion column D cMeOH(D1) is preferably about equal to cMeOH(1) with 0.95 ≤ cMeOH(1) / cMeOH(D1) ≤ 1.05. W(2) is preferably fed into rectification column D at a position I(2), wherein the methanol concentration at that position I(2) within the rectification column D cMeOH(D2) is preferably about equal to cMeOH(2) with 0.95 ≤ cMeOH(2) / cMeOH(D2) ≤ 1.05. This preferred feeding manner enables a most efficient processing of rectification column D. In some preferred embodiments of the process, stream W(1) comprises methanol and water at a molar methanol-to-water ratio r(1) and wherein the stream W(2) comprises methanol and wa- ter at a molar methanol-to-water ratio r(2) with r(2) < r(1). Preferably, the process comprises(g) feeding a stream M comprising methanol into the rectification column D at a position I(M);wherein the positions I(1) and I(2) are located below the position I(M).- Concept BCDGenerally, as indicated above, it is preferred according to the process of the present invention that at least a part of one or more of the top streams W(i) is fed into rectification column D. In some preferred embodiments, (f) comprises(f.1) feeding at least a part of the top stream W(1) into the lower part of the rectificationcolumn D at a position I(1);(f.2) at least partially condensing at least a part of the top stream W(2), obtaining an atleast partially condensed stream WC(2), and feeding at least a part of the stream WC(2) into the rectification column at a position I(2)(f.3) feeding at least a part ofthe stream TC(1a) into the rectification column D.Feeding of at least a part of the stream TC(1a) into the rectification column D according to (f.3) ispreferably done as explained in more detail herein. -Concept BRegarding these preferred embodiments with (f) comprising (f.1), (f.2) and (f.3), the process in one alternative preferably comprises(g) feeding a stream M comprising methanol into the rectification column D at a position I(M);wherein (f.2’) comprises passing the top stream W(2) having a temperature TW(2) through at least one heat exchanger E, obtaining an at least partially condensed stream WC(2) having a temperature TWC(2) with TWC(2) < TW(2), and feeding at least a part of the at least partially con- densed stream WC(2) into the rectification column D at the position I(2); and wherein (g) comprises passing the stream M having a temperature TM1through one or more of said at least one of heat exchangers E, obtaining a stream M having a temperature TM2 with TM2 > TM1, and feeding the stream M having the temperature TM2 into the rectification column D at the position I(M). Preferably, at least partially condensing at least a part of the top stream W(2), obtaining an at least partially condensed stream WC(2), and feeding at least a part of the stream WC(2) into therectification column at a position I(2) comprises passing the top stream W(2) having a tempera-ture TW(2) through a heat exchanger E(1a), obtaining a partially condensed stream WC(2) having a temperature TWC(2) with TWC(2) < TW(2); feeding at least a part of the at least partially condensed stream WC(2) into the rectification column D at the position I(2). In these preferred embodiments, (g) preferably comprises (g.1) passing the stream M having the temperature TM1 through the heat exchangerE(1a), obtaining the stream M having the temperature TM2; (g.2) feeding the stream M having the temperature TM2 into f the rectification column D atthe position I(M). In some preferred embodiments, at least partially condensing at least a part of the top stream W(2), obtaining an at least partially condensed stream WC(2), and feeding at least a part of thestream WC(2) into the rectification column at a position I(2) comprises passing the top streamW(2) having a temperature TW(2) through a heat exchanger E(1a), obtaining a partially con- densed stream WC1(2) having a temperature TWC1(2) with TWC1(2) < TW(2); passing the stream WC(2) having the temperature TWC1(2) through a heat exchanger E(1b), obtaining a stream WC2(2) having a temperature TWC2(2) with TWC2(2) < TWC1(2); feeding at least a part of the streamWC2(2) into the rectification column D at the position I(3).Preferably, I(M) is above I(2) and I(2) is above I(1). In these preferred embodiments, (g) preferably comprises(g.1) passing the stream M having the temperature TM1 through the heat exchangerE(1a), obtaining the stream M having the temperature TM2;(g.2) feeding at least a part of the stream M having the temperature TM2 into the rectifica-tion column D at the position I(M). The methanol concentration in stream W(1) cMeOH(1) is preferably higher than the methanol con- centration in W(2) cMeOH(2) with cMeOH(1) > cMeOH(2). W(1) is fed into rectification column D at a position I(1), wherein the methanol concentration at that position I(1) within the rectification col- umn D cMeOH(D1) is preferably about equal to cMeOH(1) with 0.95 ≤ cMeOH(1) / cMeOH(D1) ≤ 1.05. At least partially condensed stream WC(2) has a methanol concentration cMeOH(2’) equal to the methanol concentration in W(2) and lower than the methanol concentration in W(1). WC(2) is preferably fed into rectification column D at a position I(2), wherein the methanol concentration at that position I(2) within the rectification column D cMeOH(D2) is preferably about equal to cMeOH(2’) with 0.95 ≤ cMeOH(2’) / cMeOH(D2) ≤ 1.05. This preferred feeding manner enables a most efficient processing of rectification column D. The same applies with respect to WC2(2). Heat emitted from stream WC1(2) in heat exchanger E(1b) is taken up by a cooling medium such as water or ambient air. I(M) is in the upper half of rectification column D, preferably in its upper third. Preferably, there is at least one, more preferably there are at least 2, theoretical stages between I(M) and the head of the rectification column D. I(2), which is above I(1), and I(1) are both in the lower half of rectification column D, preferably both in its lower third, wherein more preferably I(2) is prefera- bly at least one, more preferably at least 5, theoretical stages above I(1). -Alternative CRegarding these preferred embodiments with (f) comprising (f.1), (f.2) and (f.3), the process in another alternative preferably comprises(g) feeding a stream M comprising methanol into the rectification column D at a position I(M);wherein (f.2) and (g) comprise passing the top stream W(2) having a temperature TW(2)through at least one heat exchanger E(2), obtaining an at least partially, preferably essentially com- pletely, condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2); and admixing the stream M, prior to feeding it into the rectification column D at the position I(M), with at least a part of the stream WC(2), wherein I(M) is preferably above I(1). The methanol concentration in stream W(1) cMeOH(1) is preferably higher than the methanol con- centration in W(2) cMeOH(2) with cMeOH(1) > cMeOH(2). W(1) is fed into rectification column D at a position I(1), wherein the methanol concentration at that position I(1) within the rectification col- umn D cMeOH(D1) is preferably about equal to cMeOH(1) with 0.95 ≤ cMeOH(1) / cMeOH(D1) ≤ 1.05. At least partially condensed stream WC(2) has a methanol concentration cMeOH(2’) equal to the methanol concentration in W(2) and lower than the methanol concentration in W(1). The mixture of WC(2) and M having a methanol concentration cMeOH(mixture) is preferably fed into rectifica- tion column D at a position I(M) , wherein the methanol concentration at that position I(M) within the rectification column D cMeOH(DM) is preferably about equal to cMeOH(mixture) with 0.95 ≤cMeOH(mixture) / cMeOH(D2) ≤ 1.05. This preferred feeding manner enables a most efficient pro-cessing of rectification column D. Heat emitted from stream W(2) in heat exchanger E(2) is taken up by a cooling medium such as water or ambient air. I(M), where the mixture of stream M and at least a part of the stream WC(2) is fed into the rectifi- cation column D is in its lower half. Preferably, there is at least one, more preferably there are at least 2, theoretical stages between I(1) and I(M). I(1) is in the lower half of rectification column D, preferably in its lower third. -Alternative DRegarding these preferred embodiments with (f) comprising (f.1), (f.2) and (f.3), the process in still another alternative preferably comprises(g) feeding a stream M comprising methanol into the rectification column D at a position I(M);wherein (f.2) and (g) comprise admixing the top stream W(2) having a temperature TW(2)with the stream M having a temperature TM1with TW(2)> TM1, thereby at least partially, preferably only partially, condensing the stream W(2), and feeding the stream obtained from mixing into the rec- tification column D at the position I(M), wherein I(M) is preferably above I(1). The methanol concentration in stream W(1) cMeOH(1) is preferably higher than the methanol con- centration in W(2) cMeOH(2) with cMeOH(1) > cMeOH(2). W(1) is fed into rectification column D at a position I(1), wherein the methanol concentration at that position I(1) within the rectification col- umn D cMeOH(D1) is preferably about equal to cMeOH(1) with 0.95 ≤ cMeOH(1) / cMeOH(D1) ≤ 1.05.The mixture of W(2) and M having a methanol concentration cMeOH(mixture) is preferably fed intorectification column D at a position I(M) , wherein the methanol concentration at that position I(M) within the rectification column D cMeOH(DM) is preferably about equal to cMeOH(mixture) with 0.95 ≤ cMeOH(mixture) / cMeOH(DM) ≤ 1.05. This preferred feeding manner enables a most efficient processing of rectification column D. I(M), where the mixture of stream M and stream W(2) is fed into the rectification column D is in its lower half. Preferably, there is at least one, more preferably there are at least 2, theoretical stages between I(1) and I(M). I(1) is in the lower half of rectification column D, preferably in its lower third. Everything described above especially applies to the process of the invention being carried out in normal run stage, i.e. after the process had been initiated in a start-up stage. Regarding the start-up stage, it is understood that for starting the process, external energy is applied, for ex- ample, external heating steam is used, or electrically heating takes place. Preferably, external heating steam (H2Ogaseous) is applied by one or more further reboiler(s). These one or more fur-ther reboiler(s) are only in use until the boiling temperature of the respective liquid phase in thebottom of the rectification column D and in the reactive distillation column K(i) has been reached and / or, preferably and, the remaining volume of the columns, which is not filled by the respec- tive liquid phase, is filled with methanol steam. Then, the one or more further reboiler(s) are taken out of operation.2nd aspect - Chemical production unitA second aspect of the present invention relates to a chemical production unit for carrying out the process according to the first aspect, comprising- a rectification column D comprising-- in its lower part, inlet means for feeding streams W(i) or one or more com-bined stream thereof into D; -- in its upper part, outlet means for removing a vapor stream V or dividedstreams thereof, comprising at least a gaseous stream G and at a stream T(1), from the top of D; -- an intermediate reboiler V(1a);-- a bottom reboiler V(1b);- optionally a stream dividing device So for dividing T(1) into sub streams thereof;- a first compressor CT(1) for compressing T(1) or a part thereof;- a second compressor CT(2) for compressing a part stream of T(1) and / or for compressinga compressed sub stream of T(1) or a part thereof;- means for passing compressed sub streams of T(1) from CT(1) and / or CT(2) as heatingmedium through intermediate reboiler V(1a) and bottom reboiler V(1b);- a stream dividing device S for dividing the stream G into n streams G(i);- means for passing the stream G to said stream dividing device S;- n reactive distillation columns K(i), n≥2 and i=1…n; said reactive distillation columns K(i)being arranged in parallel, each reactive distillation column K(i) comprising -- in its upper part, preferably in its top, inlet means for feeding a stream H(i) intoK(i); -- in its lower part, inlet means for feeding a stream G(i) into K(i);-- outlet means for removing a stream W(i) from the top of K(i);-- bottom reboilers VK(i);-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms streamremoved from K(i);- means for passing the streams G(i) to the reactive distillation columns K(i);- means for passing the streams W(i) to the rectification column D;- one or more compressors CG(i) for compressing either the stream G and / or the streamsG(i) and / or the streams W(i).In some preferred embodiments, the chemical production unit further comprises a trans alcohol-isation unit TAU, wherein TAU comprises- a reactive distillation column comprising-- inlet means for feeding a stream comprising alkali metal methoxide A(i)OMe intoTAU; -- inlet means for feeding a stream comprising alcohol HOX into TAU;-- outlet means for removing a stream S(2) comprising methanol from the upper part ofTAU; -- bottom reboiler VTAU;-- outlet means for removing a bottoms stream S(1) comprising alkali metal alkoxideA(i)OX and alcohol XOH from TAU; the chemical production unit further comprising- means for passing a bottoms stream comprising alkali metal methoxide A(i)OMe from K(i)to TAU;- optionally means for passing the stream S(2) comprising methanol to the rectification col-umn D and / or to the reactive distillation columns K(i). In some preferred embodiments, the chemical production unit comprises a third compressor CT(3) for compressing sub streams of T(1) or for compressing compressed sub streams of T(1). In some preferred embodiments of the chemical production unit, the reactive distillation columns K(i) comprise bottom reboilers VK(i) and the chemical production unit comprises means for passing compressed sub streams of T(1) as heating medium through one or more bottom re- boilers VK(i). In some preferred embodiments, the chemical production unit comprises means for passingcondensed sub streams of T(1) after passage through intermediate reboiler V(1a) and / or bottomreboiler V(1b) and / or bottom reboilers VK(i) into D, the means preferably comprising- at least one condenser, preferably a condenser V(2) and optionally a further condenserV(3) arranged downstream of V(2), having inlet means for receiving condensed sub streams of T(1) after passage through intermediate reboiler V(1a) and / or bottom reboiler V(1b) and / or bottom reboilers VK(i), and having outlet means for removing a condensed stream T(3) and for removing a waste gas stream;- inlet means for feeding the stream T(3) to the top of D. In some preferred embodiments, the chemical production unit comprises inlet means for feeding a methanol stream M into D. Preferably, the top of at least one, more preferably of each reactive distillation column K(i) is equipped with a droplet separating device D(i), more preferably a demister, said demister more preferably comprising an inlet means for feeding a stream M(i) comprising methanol into said demister. Preferably each of the reactive distillations columns K(i) comprises, independently from one another, from 5 to 50, more preferably from 10 to 40, more preferably from 15 to 30 theoretical stages. It is preferred that the means for passing the streams G(i) to the reactive dis- tillation columns K(i) are located, independently from one another, at a position between the bottoms and the fifth theoretical stage, more preferably between the bottoms and the third theo- retical stage, more preferably between the bottoms and the second theoretical stage of K(i). Preferably, the means for passing the streams H(i) into the reactive distillation columns K(i) are located at the top of K(i), preferably at the uppermost theoretical stage. Preferably at least one, more preferably each reactive distillation columns K(i) does not comprise means for being oper- ated at a reflux ratio of greater than 0:1. Preferably each reactive distillation column K(i) is equipped with trays. It is preferred that the chemical production unit of the present invention comprises at least one compression unit CG arranged upstream of K(i) for compressing the stream G before passage into the stream dividing device S. Alternatively, it is preferred that the unit of the present inven-tion comprises n compression units C(i) arranged downstream of K(i) and upstream of D forcompressing the streams W(i). As to the rectification column D, it is preferred that said column has from 20 to 100, more prefer- ably from 30 to 80, more preferably from 40 to 60 theoretical stages. Preferably, the inlet means of D for feeding the streams W(i) or one or more combined stream thereof into D is / are located at a position between the bottoms and the 15ththeoretical stage, more preferably between the bottoms and the 10ththeoretical stage, more preferably between the bottoms and the 8ththeo- retical of D. It is preferred that the inlet means for feeding the stream M into D are located at least 4 theoretical stages from the top of D, more preferably between the 4thand the 20ththeo- retical stage from the top of D, more preferably between the 6thand the 15ththeoretical stage from the top of D. It is preferred that the unit of the present invention further comprises at least one condensate drum (second condensate drum CD(2)) for a liquid stream removed from V(2) and optionally from V(3) and further comprising means for passing at least part of the liquid contained in said second condensate drum CD(2) in depressurized form as the stream T(3) to the top of D. Ac- cording to the present invention, it is preferred that the unit further comprises at least one (first) condensate drum CD(1) for the condensed stream removed from intermediate reboiler V(1a) and / or bottom reboiler V(1b) and / or bottom reboilers VK(i), the unit more preferably further com- prising means for passing at least part of a gas phase obtained in said first condensate drum CD(1) to V(2) and means for passing at least part of a liquid phase obtained in said first conden-sate drum CD(1) to a second condensate drum CD(2) as defined in the foregoing.In the context of the present invention, it is also conceivable that suitable reactive distillation col- umns K(i) are essentially bubble cap tray, valve tray and sieve tray columns. Specifically in the case of valve trays and sieve trays, the trays should be configured so that the raining-through of the liquid is minimized. A person skilled in the art will be familiar with the constructional measures required for this. It is also conceivable that the columns are provided with random packing elements or structured packings, with structured packings being preferred over random packing elements with a view to uniform distribution of the liquid. Further, it may be preferred that the unit further comprises means for separating an alkali metal methoxide A(i)OMe from at least one of the streams P(i). Preferably, the number of reactive dis- tillation columns K(i), n, is in the range of from 2 to 10, more preferably in the range of from 2 to 5, more preferably 2 or 3, more preferably 2. All details, embodiments and preferred embodiments as well as alternative (preferred) embodi- ments described above in the section related to the first aspect of the invention apply also for the second aspect of the invention.3rd aspect – UseA third aspect of the present invention relates to the use of a chemical production unit according to the second aspect of the invention or of a process according to the first aspect of the present invention for simultaneously producing n mixtures P(i) comprising alkali metal methoxide and methanol, n being an integer with n≥2 and i=1…n, wherein either at least 2 of the mixtures P(i) comprise different alkali metal methoxides A(i)OMe, and / or at least 2 of the mixtures P(i) comprise the same alkali metal alkoxide A(i)OMe at differ- ent concentrations. All details, embodiments and preferred embodiments as well as alternative (preferred) embodi- ments described above in the section related to the first aspect of the invention or in the section related to the second aspect of the invention apply also for the third aspect of the invention. The present invention is further illustrated by the following set of embodiments and combina-tions of embodiments resulting from the dependencies and back-references as indicated. In par-ticular, it is noted that in each instance where a range of embodiments is mentioned, for exam-ple in the context of a term such as "The integrated process of any one of embodiments 1 to 4",every embodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The in-tegrated process of any one of embodiments 1, 2, 3 and 4". Further, it is explicitly noted that thefollowing set of embodiments represents a suitably structured part of the general description di- rected to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention.1. An integrated process for simultaneously preparing n mixtures P(i) comprising alkali metalmethoxide and methanol, comprising providing n reactive distillation columns K(i); providing n aqueous liquid streams H(i), a given stream H(i) comprising a dissolved alkali metal hydroxide A(i)OH, wherein n is an integer with n≥2 and i=1…n; and providing a rectification column D comprising at least one intermediate reboiler V(1a) and at least one bottom reboiler (V1b); providing a first compression unit CT(1), a second compression unit CT(2) and at least one further compression unit CG; wherein the process comprises preparing the one or more alkali metal methoxides in the n reactive distillation column K(i) under reactive distillation conditions from the n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streams W(i) com- prising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further comprising (a) obtaining a vapor phase V comprising methanol at the top of the rectification columnD, said vapor phase V having a pressure pVand a temperature TV; (b) preparing at least three streams from the vapor phase V, said at least three streams comprising a vapor stream G having a pressure pGand a temperature TGwith pG= pVand TG= TV, and further comprising two streams T(1a) and T(1b), said stream T(1a) having a pressure pT(1a)and a temperature TT(1a)with pT(1a)> pVand TT(1a)> TVand said stream T(1b) having a pressure pT(1b)and a temperature TT(1b)with pT(1b)> pVand TT(1b)> TV, wherein for preparing the streams T(1a) and T(1b), the first com- pression unit CT(1) and the second compression unit CT(2) are employed; (c) preparing n streams G(i) from the vapor stream G, each of the streams G(i) having apressure pG(i) and a temperature TG(i) with pG(i) > pG and TG(i) > TG for each stream G(i), and feeding each stream G(i) into the respective reactive distillation column K(i), wherein for preparing the n streams G(i), the at least one compression unit CG is employed;(d) passing at least a part of the stream T(1a) as a heating medium through an interme-diate reboiler V(1a) of the rectification column D, obtaining a stream TC(1a) having a temperature TTc(1a)with TTc(1a)< TT(1a);(e) passing at least a part of the stream T(1b) as a heating medium through a bottomreboiler V(1b) of the rectification column D, obtaining a stream TC(1b) having a tem-perature TTc(1b) with TTc(1b) < TT(1b);(f) feeding one or more of(f.1) at least a part of one or more of the top streams W(i),(f.2) at least a part of the stream TC(1a), and(f.3) at least a part of the stream TC(1b)into the rectification column D.The process of embodiment 1, wherein preparing the at least three streams according to(b) comprises(b.1) splitting the vapor phase V into at least two vapor streams comprising thestream G and a vapor stream T(1) having a pressure pT(1) and a temperature TT(1) with 0.95 ≤ pT(1) / pV ≤ 1.00;(b.2) preparing at least the two streams T(1a) and T(1b) from the vapor streamT(1).The process of embodiment 1 or 2, wherein the rectification column D is operated at apressure at the top of D ptD in the range of from 0.5 to 10 bar(abs), preferably in the range of from 0.75 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs), more pref- erably in the range of from 1 to 3 bar(abs).The process of any one of embodiments 1 to 3, wherein the rectification column D is oper-ated at a temperature at the top of D TtD in the range of from 45 to 137 °C, preferably inthe range of 49 to 118, more preferably in the range of from 64 to 111 °C, more preferablyin the range of from 64 to 95°C.The process of any one of embodiments 1 to 4, wherein the rectification column D is oper-ated at a reflux ratio of at least 0.5:1, preferably in the range of from 0.55:1 to 1.4:1, more preferably in the range of from 0.6:1 to 1.4:1.The process of embodiment 5, wherein the rectification column is operated with top vaporrecompression.The process of embodiment 6, wherein realizing the reflux ratio comprises preparing fromthe vapor phase V a further vapor stream T(2), passing said stream T(2) through a con- denser V(2), obtaining a liquid stream T(3) and a waste gas stream T(2w), and feeding the liquid stream T(3) into the top of the rectification column D.The process of embodiment 7, wherein the waste gas stream T(2w) essentially consists ofoxygen, nitrogen, carbon dioxide and methanol, wherein the amount of methanol in T(2w) is preferably in the range of from 2 to 80 weight-%, preferably in the range of from 10 to 30 weight-% based on the total weight of T(2w).The process of any one of embodiments 2 to 9, wherein (b.2) comprises splitting vaporstream T(1) into at least two streams and passing a first part stream of T(1) through the first compression unit CT(1), obtaining T(1a), and passing a second part stream of T(1)through the second compression unit CT(2), obtaining T(1b).The process of any one of embodiments 2 to 9, wherein (b.2) comprises passing vaporstream T(1) through the first compression unit CT(1), obtaining T(1a); and passing a part of T(1a) through the second compression unit CT(2), obtaining T(1b).The process of any one of embodiments 1 to 11, wherein Tc(1a) and / or Tc(1b), preferablyTc(1a) and Tc(1b), each at least partially, is / are fed to a first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liq- uid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D.The process of any one of embodiments 1 to 12, wherein a further stream T(2) is pre-pared from the vapor phase V and said stream T(2) is passed through the condenser V(2), obtaining a liquid stream T(2l) and a gas stream T(2g); wherein the gas stream T(2g) is passed through a condenser V(3), obtaining a liquid stream T(2gl) and a waste gas stream T(2w); and the liquid streams T(2l) and (T2gl) are combined in a second conden- sate drum CD(2) in depressurized form.The process of any one of embodiments 1 to 13, wherein Tc(1a) at least partially is fed to a first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form; and Tc(1b) at least partially is fed to a third condensate drum CD(3), wherein from said third condensate drum CD(3) a gaseous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into the vapor phase V and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into the vapor phase V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor phase V, and from said condensate drum CD(3) further a liquid stream T(5) is obtained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in de- pressurized form, obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D.15. The process of any one of embodiments 10 to 14, wherein the n reactive columns K(i)have each a reboiler, preferably bottom reboiler, VK(i) and wherein (e) comprises (e.1) passing at least a first part of the stream T(1b) (T(1b.1)) as a heating mediumthrough a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b.1) having a temperature TTc(1b.1)with TTc(1b.1)< TT(1b); (e.2) passing at least a second part of stream T(1b) (T(1b.2)) as a heating mediumthrough at least one bottom reboiler VK(i) of one of the n reactive distillation column K(i), obtaining a stream TC(1b.2) having a temperature TTc(1b.2) with TTc(1b.2) < TT(1b).16. The process of embodiment 15, wherein stream TC(1b.2) is fed into the first condensatedrum CD(1).17. The process of embodiment 15, whereinat least a part of Tc(1a) is fed to the first condensate drum CD(1), wherein from said firstcondensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form; and Tc(1b.1) and / or TC(1b.2), preferably Tc(1b.1) and TC(1b.2), at least partially is / are fed to the third condensate drum CD(3), wherein from said third condensate drum CD(3), the gase- ous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into vapor stream V and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into vapor stream V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor stream V, and from said third condensate drum CD(3) further the liquid stream T(5) is ob- tained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in depressurized form, thereby obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D.8. The process of any one of embodiments 1 to 17, wherein at least one of the n bottomsstreams P(i) comprising alkali metal methoxide A(i)OMe and methanol is at least partially fed to a trans alcoholisation unit TAU, wherein (x) the (part)stream comprising alkali metal methoxide A(i)OMe and methanol is con-tacted in the trans alcoholisation unit TAU with an alcohol HOX, wherein X repre- sents an alkyl residue selected from the group consisting of C2 to C10 alkyl, prefera-bly C2 alkyl, thereby obtaining a stream S(1) comprising alkali metal alkoxide A(i)OXand alcohol XOH and a stream S(2) comprising methanol;(y) removing the stream S(2) comprising methanol from the trans alcoholisation unitTAU, preferably as a liquid stream, more preferably as a liquid top stream; and re-moving the stream S(1) comprising alkali metal alkoxide A(i)OX and alcohol XOHfrom the trans alcoholisation unit TAU, preferably as a liquid stream, more preferablyas a liquid stream from the lower part of TAU, more preferably as a liquid bottomsstream.19. The process of embodiment 18, wherein the liquid stream S(2) is obtained in that a gase-ous stream S(O) is obtained within TAU, which is condensed within TAU, preferably usingan internal condenser.20. The process of embodiment 18 wherein the liquid stream S(2) is obtained in that a gase-ous stream S(O) is removed from the upper part of TAU, preferably from the top of TAUand passed through at least one heat exchanger; thereby obtaining from the heat ex-changer at least one, preferably liquid, stream S(2) comprising methanol; wherein prefera- bly at least a part of stream S(2) is reintroduced into TAU, preferably in the upper part of TAU, preferably at a feeding point TAU(S(2)).21. The process of embodiment 20, wherein at least 90 volume-%, preferably at least 95 vol-ume-%, of stream S(2) are reintroduced into TAU at feeding point TAU(S(2)), wherein preferably, at least a stream S(2.a) comprising methanol is removed from TAU at a posi- tion TAU(S(2a)), wherein TAU(S(2a)) is located below TAU(S(2)).22. The process of any one of embodiments 18 to 21, wherein the trans alcoholisation unitTAU has a reboiler, preferably bottom reboiler, VTAU.23. The process of any one of embodiments 18 to 22, wherein (e) comprises(e.1) passing at least a first part of the stream T(1b) (T(1b.1)) as a heating mediumthrough a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b.1) having a temperature TTc(1b.1) with TTc(1b.1) < TT(1b); (e.2) passing at least a second part of stream T(1b) (T(1b.2))as a heating medium through at least one bottom reboiler VK(i) of one of the n reactive distillation column K(i), obtaining a stream TC(1b.2) having a tempera- ture TTc(1b.2) with TTc(1b.2) < TT(1b), (e.3) passing at least a third part of stream T(1b) (T(1b.3)) as a heating mediumthrough the bottom reboiler VTAU of the trans alcoholisation unit TAU, obtaining a stream TC(1b.3) having a temperature TTc(1b.3) with TTc(1b.x) < TT(1b).24. The process of embodiment 23, wherein stream TC(1b.3) is fed into the first condensatedrum CD(1).25. The process of embodiment 23, whereinat least a part of Tc(1a) is fed to the first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form; and TC(1b.1) and / or TC(1b.2), and / or TC(1b.3), preferably TC(1b.1) and TC(1b.2) and TC(1b.3), at least partially is / are fed to the third condensate drum CD(3), wherein from said third condensate drum CD(3), the gaseous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into vapor stream V and / or into the stream G and / or intothe stream T(1), preferably into the top of the rectification column D or into vapor stream V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor stream V, and from said third condensate drum CD(3) further the liquid stream T(5) is obtained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in depressur- ized form, thereby obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D.26. The process of any one of embodiments 18 to 22, wherein (e) comprises(e.1) passing at least a first part of the stream T(1b) (T(1b.1)) as a heating mediumthrough a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b.1) having a temperature TTc(1b.1) with TTc(1b.1) < TT(1b);(e.2.1) splitting a second part of stream T(1b) (T(1b.2)) into at least two sub-streams(T(1b.2.1)) and (T(1b.2.2);(e.2.2) passing at least sub-stream (T(1b.2.1)) as a heating medium through at leastone bottom reboiler VK(i) of one of the n reactive distillation column K(i), ob- taining a stream TC(1b.2.1) having a temperature TTc(1b.2) with TTc(1b.2.1) < TT(1b);(e.2.3) passing at least subs-stream (T(1b.2.2)) as a heating medium through the bot-tom reboiler VTAU of the trans alcoholisation unit TAU, obtaining a stream TC(1b.2.2) having a temperature TTc(1b.2.2) with TTc(1b.2.2) < TT(1b).The process of embodiment 26, wherein stream TC(1b.2.2) is fed into the first condensatedrum CD(1).The process of embodiment 26, whereinat least a part of Tc(1a) is fed to the first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form; and TC(1b.1) and / or TC(1b.2.1), and / or TC(1b.2.2), preferably TC(1b.1) and TC(1b.2.1) and TC(1b.2.2), at least partially is / are fed to the third condensate drum CD(3), wherein from said third condensate drum CD(3), the gaseous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into vapor stream V and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into va- por stream V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor stream V, and from said third condensate drum CD(3) further the liquid stream T(5) is obtained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in depressurized form, thereby obtaining a combined liquid stream from the second conden- sate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D.The process of any one of embodiments 18 to 22, wherein (d) comprises(d.1) passing at least a first part of the stream T(1a) (T1a.1) as a heating medium throughan intermediate reboiler V(1a) of the rectification column D, obtaining a stream TC(1a.1) having a temperature TTc(1a.1)with TTc(1a.1)< TT(1a.1);(d.2) passing at least a second part of stream T(1a) (T(1a.2)) as a heating mediumthrough the bottom reboiler VTAU of the trans alcoholisation unit TAU, obtaining a stream TC(1a.2) having a temperature TTc(1a.2) with TTc(1a.2) < TT(1a).30. The process of embodiment 29, wherein stream TC(1a.2) is fed into the first condensatedrum CD(1).31. The process of embodiment 29, whereinat least a part of Tc(1a.1) and Tc(1a.2) at least partially are fed to the first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in de- pressurized form; and Tc(1b.1) and / or TC(1b.2), preferably Tc(1b.1) and TC(1b.2), at least partially is / are fed to the third condensate drum CD(3), wherein from said third condensate drum CD(3), the gase- ous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into vapor stream V and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into vapor stream V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor stream V, and from said third condensate drum CD(3) further the liquid stream T(5) is ob- tained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in depressurized form, thereby obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as thestream T(3) into the top of the rectification column D.32. The process of any one of embodiments 1 to 31, comprising providing a providing a thirdcompression unit CT(3), wherein (b) comprises preparing at least four streams from the vapor phase V, said at least four streams comprising vapor stream G, stream T(1a), stream T(1b), and a further stream T(1c), said stream T(1c) having a pressure pT(1c)and a temperature TT(1c)with pT(1c)> pVand TT(1c)> TV, wherein for preparing the stream T(1c), the third compression unit CT(3) is employed.33. The process of embodiment 32, wherein Tc(1a) and / or Tc(1b), preferably Tc(1a) andTc(1b), each at least partially, is / are fed to a first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are re- moved, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depressurized form, ob- taining a combined liquid stream which is fed as the stream T(3) into the top of the rectifi- cation column D.34. The process of embodiment 32 or 34, wherein the n reactive columns K(i) have each a re-boiler, preferably bottom reboiler, VK(i) and wherein at least a part of T(1c) is passed as heating medium through at least one bottom reboiler VK(i) of one of the n reactive distilla- tion column K(i), obtaining a stream TC(1c) having a temperature TTc(1c) with TTc(1c) < TT(1c).35. The process of any one of embodiments 1 to 34, wherein vapor phase V has a pressurepV, in the range of from 0.5 to 10 bar(abs), preferably in the range of from 0.75 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs), more preferably in the range of from 1 to 3 bar(abs).36. The process of any one of embodiments 1 to 35, wherein vapor phase V has a tempera-ture TV in the range of from45 to 137 °C, preferably in the range of 49 to 118, more prefer-ably in the range of from 64 to 111 °C, more preferably in the range of from 64 to 95°C .37. The process of any one of embodiments 1 to 36, wherein a stream T(Di) having a temper-ature TT(Di) is taken from the rectification column D at an intermediate position and passed for heating purpose through the intermediate reboiler V(1a) of the rectification column D, obtaining a heated stream Th(Di) having a temperature TTh(Di) with TTh(Di) > TT(Di), whereinheated stream Th(Di) is reintroduced into rectification column D; and wherein a stream T(Db) having a temperature TT(Db) is taken from the rectification column D at a bottom position and passed for heating purpose through the bottom reboiler V(1b) of the rectification column D, obtaining a stream Th(Db) having a temperature TTh(Db)with TTh(Db) > TT(Db), wherein heated stream Th(Db) is reintroduced into rectification column D.38. The process of any one of embodiments 1 to 37, wherein a bottom stream T(Ki) having atemperature TT(Ki)is taken from the bottom of the n reactive columns K(i) and passed for heating purpose through a bottom reboiler VK(i), thereby obtaining a heated stream Th(Ki) having a temperature ThT(Ki) and wherein ThT(Ki) > TT(Ki); wherein heated stream Th(Ki) is re-introduced into rectification column D.39. The process of any one of embodiments 2 to 38, wherein stream T(1) has a temperatureTT(1)with 0.95 ≤ TT(1) / TV≤ 1.00 and / or a pressure pT(1)with with 0.95 ≤ pT(1) / pV≤ 1.00.40. The process of any one of embodiments 37 to 39, wherein stream T(1a) has a pressurepT(1a), which is adjusted so thatTcondT(1a) is ≥ TboilT(Di) + 3 K, wherein TcondT(1a) is the conden-sation temperature of stream T(1a) at a pressure pT(1a) and TboilT(Di) is the boiling tempera-ture of stream T(Di) at a pressure pT(Di).41. The process of any one of embodiments 37 to 40, wherein stream T(1a) has a condensa-tion temperature TcondT(1a) which is in the range of from 3 to 30 K, preferably in the range offrom 4 and 25 K, more preferably in the range of from 5 and 20 K, higher than TboilT(Di).42. The process of any one of embodiments 37 to 41, wherein stream T(1b) has a pressurepT(1b) , which is adjusted so that TcondT(1b) is ≥ TboilT(Db) + 3 K, wherein TcondT(1b) is the conden-sation temperature of stream T(1b) at a pressure pT(1b) and TboilT(Db) is the boiling tempera-ture of stream T(Db) at a pressure pT(Db).43. The process of any one of embodiments 37 to 42, wherein T(1b) has a condensation tem-perature TcondT(1b) which is in the range of from 3 to 30 K, preferably in the range of from 4and 25 K, more preferably in the range of from 5 and 20 K, higher than TboilT(Db).44. The process of any one of embodiments 38 to 43, wherein stream T(1c) has a pressurepT(1c), which is adjusted so that TcondT(1c) is ≥ TboilT(Ki) + 3 K, wherein TcondT(1c) is the conden-sation temperature of stream T(1c) at a pressure pT(1c) and Tboil T(Ki)) is the boiling tempera-ture of stream T(Ki).45. The process of any one of embodiments 14 to 44, wherein the gaseous stream T(4) has apressure pT(4) in the range of pT(1b) > pT(4) > pV..46. The process of any one of embodiments 1 to 45, further comprising(g) feeding a stream M comprising methanol into the rectification column D at a positionI(M).47. The process of any one of embodiments 1 to 46, further comprising for at least one reac-tive distillation column K(i), preferably for n reactive distillation columns K(i), feeding the stream G(i) into the lower part of the reactive distillation column K(i) and feeding the aque- ous liquid stream H(i) into the upper part of the reactive distillation column K(i).48. The process of any one of embodiments 1 to 47, wherein a stream H(1) comprises dis-solved sodium hydroxide and a stream H(2) comprises dissolved potassium hydroxide, wherein sodium methoxide is prepared in the reactive distillation column K(1) from which the stream W(1) is obtained and potassium methoxide is prepared in the reactive distilla- tion column K(2) from which the stream W(2) is obtained.49. The process of any one of embodiments 1 to 48, wherein n = 2.50. The process of any one of embodiments 1 to 49, wherein (f.1) comprises(f.1.1) feeding at least a part of the top stream W(1) into the lower part of the rectifica-tion column D at a position I(1); (f.1.2) feeding at least a part of the top stream W(2) into the lower part of the rectifica-tion column D at a position I(2), wherein the position I(2) is located below the po- sition I(1); wherein between the positions I(1) and I(2), the rectification column D is equipped with in- ternals.51. The process of embodiment 50, wherein the stream W(1) comprises methanol and waterat a molar methanol-to-water ratio r(1) and wherein the stream W(2) comprises methanol and water at a molar methanol-to-water ratio r(2) with r(2) < r(1).52. The process of embodiment 50 or 51, comprising(g) feeding a stream M comprising methanol into the rectification column D at a positionI(M); wherein the positions I(1) and I(2) are located below the position I(M).53. The process of any one of embodiments 1 to 49, wherein (f) comprises(f.1) feeding at least a part of the top stream W(1) into the lower part of the rectifica-tion column D at a position I(1); (f.2) at least partially condensing at least a part of the top stream W(2), obtaining an atleast partially condensed stream WC(2), and feeding at least a part of the stream WC(2) into the rectification column at a position I(2); (f.3) feeding at least a part of the stream TC(1a) into the rectification column D.54. The process of embodiment 53, comprising(g) feeding a stream M comprising methanol into the rectification column D at a positionI(M); wherein (f.2’) comprises passing the top stream W(2) having a temperature TW(2)through at least one heat exchanger E, obtaining an at least partially condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2), and feeding at least a part of the at least partially condensed stream WC(2) into the rectification column D at the position I(2); and wherein (g) comprises passing the stream M having a temperature TM1 through one or more of said at least one of heat exchangers E, obtaining a stream M having a tempera- ture TM2 with TM2 > TM1, and feeding the stream M having the temperature TM2 into the rec-tification column D at the position I(M).55. The process of embodiment 53, comprising(g) feeding a stream M comprising methanol into the rectification column D at a positionI(M); wherein (f.2) and (g) comprise passing the top stream W(2) having a temperature TW(2)through at least one heat exchanger E(2), obtaining an at least partially, preferably essen- tially completely, condensed stream WC(2) having a temperature TWC(2) with TWC(2) < TW(2); and admixing the stream M, prior to feeding it into the rectification column D at the posi- tion I(M), with at least a part of the stream WC(2), wherein I(M) is preferably above I(1).56. The process of embodiment 53, comprising(g) feeding a stream M comprising methanol into the rectification column D at a positionI(M); wherein (f.2) and (g) comprise admixing the top stream W(2) having a temperature TW(2) with the stream M having a temperature TM1 with TW(2) > TM1, thereby at least partially, preferably only partially, condensing the stream W(2), and feeding the stream obtained from mixing into the rectification column D at the position I(M), wherein I(M) is preferably above I(1).57. A chemical production unit for carrying out the process according to any one of embodi-ments 1 to 56, comprising -a rectification column D comprising-- in its lower part, inlet means for feeding streams W(i) or one or more com-bined stream thereof into D; -- in its upper part, outlet means for removing a vapor stream V or dividedstreams thereof, comprising at least a gaseous stream G and at a stream T(1), from the top of D; -- an intermediate reboiler V(1a);-- a bottom reboiler V(1b);- optionally a stream dividing device So for dividing T(1) into sub streams thereof;- a first compressor CT(1) for compressing T(1) or a part thereof;- a second compressor CT(2) for compressing a part stream of T(1) and / or for com-pressing a compressed sub stream of T(1) or a part thereof;- means for passing compressed sub streams of T(1) from CT(1) and / or CT(2) as heat-ing medium through intermediate reboiler V(1a) and bottom reboiler V(1b);- a stream dividing device S for dividing the stream G into n streams G(i);- means for passing the stream G to said stream dividing device S;- n reactive distillation columns K(i), n≥2 and i=1…n; said reactive distillation columnsK(i) being arranged in parallel, each reactive distillation column K(i) comprising -- in its upper part, preferably in its top, inlet means for feeding a stream H(i) intoK(i); -- in its lower part, inlet means for feeding a stream G(i) into K(i);-- outlet means for removing a stream W(i) from the top of K(i);-- bottom reboilers VK(i);-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms streamremoved from K(i);- means for passing the streams G(i) to the reactive distillation columns K(i);- means for passing the streams W(i) to the rectification column D;- one or more compressors CG(i) for compressing either the stream G and / or thestreams G(i) and / or the streams W(i).The chemical production unit of embodiment 57 further comprising a trans alcoholisationunit TAU, wherein TAU comprises- a reactive distillation column comprising-- inlet means for feeding a stream comprising alkali metal methoxide A(i)OMeinto TAU; -- inlet means for feeding a stream comprising alcohol HOX into TAU;-- outlet means for removing a stream S(2) comprising methanol from the upperpart of TAU; -- bottom reboiler VTAU;-- outlet means for removing a bottoms stream S(1) comprising alkali metalalkoxide A(i)OX and alcohol XOH from TAU; the chemical production unit further comprising- means for passing a bottoms stream comprising alkali metal methoxide A(i)OMefrom K(i) to TAU;- optionally means for passing the stream S(2) comprising methanol to the rectifica-tion column D and / or to the reactive distillation columns K(i).59. The chemical production unit of embodiment 57 or 58 comprising a third compressor CT(3)for compressing sub streams of T(1) or for compressing compressed sub streams of T(1).60. The chemical production unit of any one of embodiments 57 to 59, wherein the reactivedistillation columns K(i) comprise bottom reboilers VK(i) and the chemical production unit comprises means for passing compressed sub streams of T(1) as heating medium through one or more bottom reboilers VK(i).61. The chemical production unit of any one of embodiment 57 to 60 comprising means forpassing condensed sub streams of T(1) after passage through intermediate reboiler V(1a) and / or bottom reboiler V(1b) and / or bottom reboilers VK(i) into D, the means preferably comprising -at least one condenser, preferably a condenser V(2) and optionally a furthercondenser V(3) arranged downstream of V(2), having inlet means for receiving condensed sub streams of T(1) after passage through intermediate reboiler V(1a) and / or bottom reboiler V(1b) and / or bottom reboilers VK(i), and having outlet means for removing a condensed stream T(3) and for removing a waste gas stream; -inlet means for feeding the stream T(3) to the top of D.62. The chemical production unit of any one of embodiment 57 to 61 comprising inlet meansfor feeding a methanol stream M into D.63. Use of a chemical production unit according to any one of embodiments 57 to 62 or of aprocess according to any one of embodiments 1 to 56 for simultaneously producing n mix-tures P(i) comprising alkali metal methoxide and methanol, n being an integer with n≥2 and i=1…n, wherein either at least 2 of the mixtures P(i) comprise different alkali metal methoxides A(i)OMe, and / or at least 2 of the mixtures P(i) comprise the same alkali metal alkoxide A(i)OMe at different concentrations. The present invention is further illustrated by the following reference examples, comparative ex-amples, and examples.Examples1. Reference Example 1: Simultaneous production of sodium methoxide andpotassium methoxide without top vapor recompression inrectification column D Fig.7 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) comprising KOMe and MeOH according to Reference Example 1. Regarding theoperating conditions of the distillation column D and of the reactive distillation columns K(1) andK(2), reference is made to Table 1a below. Regarding the relative mass flow rates, reference is made to Table 1b below. Table 1aOperating conditions of the columns D, K(1) and K(2)Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Column DTemperature at the bottom / °C 124Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 1b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from V(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in waterf(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55Ratios of f(M(2)) / f(H(2)) 0.40mass flow rates f(T(3)) / f(G) *) 0.92of streams f(P(1)) / f(H(1)) 2.25f(P(2)) / f(H(2)) 1.86f(waste gas) / f(G) *) < 0.0015*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water.P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water.In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According to this calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1), fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)1.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg1.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg1.3 fMeOH(water) = 0.001 * f(water) (maximum value)1.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water (bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.1.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:1.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg1.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg1.5.3 fH2O(M) = 0.001 * f(M)1.5.4 fH2O(waste gas) = 0 (neglected)2. Reference Example 2: Simultaneous production of sodium methoxide andpotassium methoxide with top vapor recompression (first compression unit) for intermediate reboiler in rectification col- umn D Fig.8 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) comprising KOMe and MeOH according to Reference Example 2. Regarding the operating conditions of the rectification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 2a below. Regarding the relative mass flow rates, refer- ence is made to Table 2b below. The use of vapor recompression reduces the energy demand of the distillation in rectification column D considerably. It is possible to have a ratio of the heat streams to V(1b) and V(1a) of about 1:4. That means, the energy demand decreases to 20 %. But about 10 % (depending on the pressure) of the energy which is transferred in V(1a) is needed as power for the compressor CT(1). All in all, there is already some energy saving by using vapor recompression. Table 2a Operating conditions of the columns D, K(1) and K(2) Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Column D Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2) Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 2b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from V(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55Ratios off(M(2)) / f(H(2)) 0.40mass flow ratesf(T(3)) / f(G) *) 1.0of streamsf(P(1)) / f(H(1)) 2.25f(P(2)) / f(H(2)) 1.86f(waste gas) / f(G) *) < 0.0015f(T(1)) / f(T(2)) 3.97*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water. P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water. In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According to this calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1), fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)2.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg2.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg2.3 fMeOH(water) = 0.001 * f(water) (maximum value)2.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water(bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.2.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:2.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg2.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg2.5.3 fH2O(M) = 0.001 * f(M)2.5.4 fH2O(waste gas) = 0 (neglected)3. Example 1: Simultaneous production of sodium methoxide and potassium methox-ide with top vapor recompression (first and second compression units) for intermediate reboiler and bottom reboiler in rectification column D Use of the second compression unit CT(2) allowed a further reduction of heating steam (H2Ogase-ous) required for the bottom reboiler V(1b) of rectification column D. Compared to Reference Ex-ample 1 (without condenser), only 2.4 % of heating steam (H2Ogaseous) were required (for operat-ing bottom reboiler VK(1) of K(1) and bottom reboiler VK(2) of K(2). Fig.9 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) comprising KOMe and MeOH. Regarding the operating conditions of the rectifi- cation column D and of the reactive distillation columns K(1) and K(2), reference is made to Ta- ble 3a below. Regarding the relative mass flow rates, reference is made to Table 3b below. Table 3a Operating conditions of the columns D, K(1) and K(2) Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Column D Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at outlet of CT(2) / bar(abs) 10Pressure at the top / bar(abs) 2.15Column K(1) Temperature at the top / °C 89Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 3b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from V(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55f(M(2)) / f(H(2)) 0.40Ratios of f(T(3)) / f(G) *) 1.0mass flow rates f(P(1)) / f(H(1)) 2.25of streams f(P(2)) / f(H(2)) 1.86f(waste gas) / f(G) *) < 0.0015f(T(1)) / f(T(2)) 41f(T(1a) / f(T1b) 4.14*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water. P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water. In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According to this calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1), fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)3.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg3.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg3.3 fMeOH(water) = 0.001 * f(water) (maximum value)3.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water (bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.3.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:3.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg3.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg3.5.3 fH2O(M) = 0.001 * f(M)3.5.4 fH2O(waste gas) = 0 (neglected)4. Example 2: Simultaneous production of sodium methoxide and potassium methox-ide with top vapor recompression (first and second compression units) for intermediate reboiler and bottom reboiler in rectification column D and use of the 2ndcompression unit also for the bottom reboilers VK(1) and VK(2) of K(1) and K(2) Fig.10 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) comprising KOMe and MeOH. Regarding the operating conditions of the rec- tification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 4a below. Regarding the relative mass flow rates, reference is made to Table 4b below. Compared to Example 1, the use of the second compression unit CT(2) combined with transfer of a first part of the resulting stream T(1b), i.e. T(1b.1), to the bottom reboiler V(1b) of rectifica- tion column D combined with transfer of a second part of the resulting T(1b), i.e. T(1b.2), to bot- tom reboilers VK(1) and VK(2) allowed a further reduction of heating steam (H2Ogaseous) required.Compared to Reference Example 1), 0 % of heating steam (H2Ogaseous) were required (for oper-ating bottom reboiler VK(1) of K(1) and bottom reboiler VK(2) of K(2).Table 4a Operating conditions of the columns D, K(1) and K(2)Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Column D Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at outlet of CT(2) / bar(abs) 10Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 4b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from V(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55Ratios of f(M(2)) / f(H(2)) 0.40mass flow rates f(T(3)) / f(G) *) 1.0of streams f(P(1)) / f(H(1)) 2.25f(P(2)) / f(H(2)) 1.86f(waste gas) / f(G) *) < 0.0015f(T(1)) / f(T(2)) 2176f(T(1a)) / f(T(1b)) 3.68f(T1b.2.1)) / f(T(1b.1) 0.091f(T1b.2.2)) / f(T(1b.1) 0.033*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water. P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water. In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According tothis calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1),fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)4.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg4.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg4.3 fMeOH(water) = 0.001 * f(water) (maximum value)4.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water(bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the watercontents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.4.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:4.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg4.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg4.5.3 fH2O(M) = 0.001 * f(M)4.5.4 fH2O(waste gas) = 0 (neglected)5. Example 3: Simultaneous production of sodium methoxide and potassium methox-ide with top vapor recompression (first and second compression units) for intermediate reboiler and bottom reboiler in rectification column D and use of a 3rdcompression unit for the bottom reboiler of K(1) and bot- tom reboiler of K(2) Fig.11 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) comprising KOMe and MeOH. Regarding the operating conditions of the rec- tification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 5a below. Regarding the relative mass flow rates, reference is made to Table 5b below. The amount of heating steam (H2Ogaseous) required is reduced to zero when using the second compression unit CT(2) for the bottom reboiler V(1b) of rectification column D and the third com- pression unit CT(3) for the reboiler VK(1) of reactive distillation column K(1) and the reboiler VK(2) or reactive distillation column K(2). Table 5a Operating conditions of the columns D, K(1) and K(2) Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Theoretical stages 50Column D W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at outlet of CT(2) / bar(abs) 10Pressure at outlet of CT(3) / bar(abs) 10Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 5b Relationships between the mass flow rates f of the different streams Definition of Specified: H(1), H(2)streams M(1), M(2): part of condensate from V(2)H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55f(M(2)) / f(H(2)) 0.40f(T(3)) / f(G) *) 1.0Ratios off(P(1)) / f(H(1)) 2.25mass flow ratesf(P(2)) / f(H(2)) 1.86of streamsf(waste gas) / f(G) *) < 0.0015f(T(1)) / f(T(2)) 2176f(T(1a)) / f(T(1b)) 4.14f(T(1a)) / f(T(1c)) 33.5f(T(1c.1)) / f(T(1c)) 0.736f(T(1c.2)) / f(T(1c)) 0.264*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water. P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water. In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According tothis calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1),fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)5.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg5.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg5.3 fMeOH(water) = 0.001 * f(water) (maximum value)5.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water (bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.5.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:5.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg5.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg5.5.3 fH2O(M) = 0.001 * f(M)5.5.4 fH2O(waste gas) = 0 (neglected)6. Example 4: (Based on Example 2) Simultaneous production of sodium methoxideand potassium methoxide with top vapor recompression (first and second compression units) for intermediate reboiler and bottom reboiler in rectifi- cation column D, use of the 2ndcompression unit also for the bottom reboil- ers VK(1) and VK(2) of K(1) and K(2) with third condensate drum CD(3) Fig.12 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) comprising KOMe and MeOH. Regarding the operating conditions of the rec- tification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 6a below. Regarding the relative mass flow rates, reference is made to Table 6b below. Table 6a Operating conditions of the columns D, K(1) and K(2) Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Theoretical stages 50Column D W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at outlet of CT(2) / bar(abs) 10Pressure in CD(3) / bar(abs) 2.2Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1) Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2) Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 6b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from CD(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55f(M(2)) / f(H(2)) 0.40f(T(3)) / f(G) *) 1.0Ratios off(P(1)) / f(H(1)) 2.25mass flow ratesf(P(2)) / f(H(2)) 1.86of streamsf(waste gas) / f(G) *) < 0.0015f(T(1)) / f(T(2)) 31Methanol to CT(1) / Methanol to CT(2) 3.68Methanol to Vk(1) / methanol to V(1b) 0.091Methanol to Vk (2) / methanol to Vk (1b) 0.033f(T(1)) / f(T(4)) 31.3*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water.P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water.In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According to this calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1), fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)6.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg6.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg6.3 fMeOH(water) = 0.001 * f(water) (maximum value)6.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water(bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.6.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:6.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg6.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg6.5.3 fH2O(M) = 0.001 * f(M)6.5.4 fH2O(waste gas) = 0 (neglected)Example 4 is based on Example 2 above. In Example 2 above, the stream T(1a), coming from the first compression unit CT(1), is passed as a heating medium through an intermediate re- boiler V(1a) of the rectification column D, obtaining a condensed stream TC(1a). The stream T(1b) is split into two streams, wherein a first part of the resulting stream T(1b), i.e. T(1b.1), is fed to the bottom reboiler V(1b) of rectification column D, from which a condensed stream TC(1b.1) is obtained. A second part of the stream T(1b), i.e. T(1b.2), is fed to bottom reboilers VK(1) and VK(2), obtaining a condensed stream TC(1b.2) after passing the reboilers VK(1) and VK(2). All the condensed streams TC(1a), TC(1b.1) and TC(1b.2) are fed into a first condensate drum CD(1). Furthermore, a further stream T(2) is prepared from the vapor phase V and passed through a condenser V(2), obtaining a liquid stream T(2l) and a gas stream T(2g); the gas stream T(2g) is in turn passed through a condenser V(3), obtaining a liquid stream T(2gl) and a waste gas stream T(2w). The liquid streams T(2l) and (T2gl) are combined in a second conden- sate drum CD(2) in depressurized form. From the first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are re- moved, said gas stream T(1g) being fed into a condenser V(2) together with stream T(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depressurized form in the second condensate drum CD(2), obtaining from said second condensate drum CD(2) a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D. Contrary to Example 2, from the condensed streams TC(1a), TC(1b.1) and TC(1b.2) only con- densed stream Tc(1a) is fed into a first condensate drum CD(1). Condensed streams TC(1b.1) and TC(1b.2) are combined in a third condensate drum CD(3) in depressurized form, wherein from said third condensate drum CD(3) a gaseous stream T(4) is obtained, which is fed into the top of the rectification column D. From said third condensate drum CD(3) further a liquid stream T(5) is obtained, which is combined with the liquid stream T(1l) and the liquid streams T(2l) and (T2gl) in depressurized form in the second condensate drum CD(2), obtaining a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D. As in Example 2, the use of the second compression unit CT(2) combined with transfer of a first part of the resulting stream T(1b), i.e. T(1b.1), to the bottom reboiler V(1b) of rectification col- umn D combined with transfer of a second part of the resulting T(1b), i.e. T(1b.2), to bottom re- boilers VK(1) and VK(2) allowed a further reduction of heating steam (H2Ogaseous) required. As in Example 2 (compared to Reference Example 1), no heating steam (H2Ogaseous) is required (for operating bottom reboiler VK(1) of K(1) and bottom reboiler VK(2) of K(2)). Furthermore, in addi- tion to Example 2, by feeding Tc(1b.1) and Tc(1b.2) into CD(3), the ratio f(T(1)) / f(T(2)) could bedrastically reduced (from 2167 as in Example 2 to 31 only). This enabled for all operation condi-tions to have enough MeOH steam as stream T(1) for operating CT(1) and CT(2).7. Example 5: (Based on Example 4) Simultaneous production of sodium methoxideand potassium methoxide with top vapor recompression (first and second compression units) for intermediate reboiler and bottom reboiler in rectifi- cation column D, use of the 2ndcompression unit also for the bottom reboil- ers VK(1) and VK(2) of K(1) and K(2) with third condensate drum CD(3) and additional further trans alcoholization unit TAU, with use of a part of streamT(1a) for heating TAU Fig.15 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOHand a mixture P(2) comprising KOMe and MeOH with an additional trans alcoholization unit(TAU), in which NaOMe is reacted with EtOH to NaOEt and MeOH. Regarding the operating conditions of the rectification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 7a below. Regarding the relative mass flow rates, reference is made to Table 7b below. Table 7a Operating conditions of the columns D, K(1) and K(2) and TAU Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Theoretical stages 50Column D W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at outlet of CT(2) / bar(abs) 10Pressure in CD(3) / bar(abs) 2.2Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40TAU Pressure at the top / bar(abs) 1Temperature at the top / °C 64.3Pressure at the bottom / bar(abs) 1.2Temperature at the bottom / °C 95.5Number of trays 80Feed to tray 40Table 7b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from CD(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in waterf(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55f(M(2)) / f(H(2)) 0.40f(T(3)) / f(G) *) 1.0f(P(1)) / f(H(1)) 2.25f(P(2)) / f(H(2)) 1.86Ratios off(waste gas) / f(G) *) < 0.0015mass flow ratesf(T(1)) / f(T(2)) 150of streamsMethanol to CT(1) / Methanol to CT(2) 3.8Methanol to VK(1) / methanol to V(1b) 0.091Methanol to VK(2) / methanol to V(1b) 0.033f(T(1)) / f(T(4)) 32.1f(Feed to TAU) / f(P(1)) 0.0235Feed ethanol / f (Feed to TAU) 1.68Reflux ratio of TAU 7T(1b.2) / T(1b.1) 0.134*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water.P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water.S(1): 21 weight-% of sodium ethoxide in ethanol, <100 ppm of methanol. S(2): methanol, <1000 ppm of ethanol In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According to this calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1), fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream:fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)7.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg7.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg7.3 fMeOH(water) = 0.001 * f(water) (maximum value)7.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water (bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.7.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:7.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg7.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg7.5.3 fH2O(M) = 0.001 * f(M)7.5.4 fH2O(waste gas) = 0 (neglected)Example 5 is based on Example 4 above. Contrary to Example 4, a part of the mixture P(1), re- moved from the column K(1), which comprises NaOMe and methanol is fed into the trans alco-holization unit, preferably into the middle section of the trans alcoholization unit TAU. A streamcomprising ethanol, is fed into a bottom reboiler VTAU of the trans alcoholisation unit TAU and therein combined with a part of the bottoms stream removed from TAU and fed into VTAU of TAU, wherein the combined stream is reintroduced into the trans alcoholisation unit TAU. A stream S(2), which comprises MeOH, is removed from the upper section of the trans alcoholisa- tion unit TAU, preferably as top stream, and a stream S(1) comprising NaOEt and enthanol, is removed as bottoms stream from the trans alcoholisation unit TAU. Contrary to Example 4, Two streams are prepared from stream T(1a), i.e. streams T(1a.1) and (T1a.2), wherein a first part stream T(1a.1) is conducted as in Example 4, i.e. passed as a heat- ing medium through the intermediate reboiler V(1a) of D and the resulting stream Tc(1a.1) is fed to the first condensate drum CD(1). T(1a.2) is fed to the bottoms reboiler of trans alcoholization unit TAU and the condensed stream Tc(1a.2) is fed to the first condensate drum CD(1). Using stream T(1a.2) as heating medium for the bottoms reboiler of trans alcoholization unit TAU VTAUallows to operate TAU without need for further external heating medium.8. Example 6: (Based on Example 4) Simultaneous production of sodium methoxideand potassium methoxide with top vapor recompression (first and second compression units) for intermediate reboiler and bottom reboiler in rectifi- cation column D, use of the 2ndcompression unit also for the bottom reboil- ers VK(1) and VK(2) of K(1) and K(2) with third condensate drum CD(3) and additional further trans alcoholization unit TAU, with use of a part of stream T(1b) for heating TAU Fig.14 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) comprising KOMe and MeOH with an additional trans alcoholization unit (TAU), in which NaOMe is reacted with EtOH to NaOEt and MeOH. Regarding the operating conditions of the rectification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 8a below. Regarding the relative mass flow rates, reference is made to Table 8b below. Table 8a Operating conditions of the columns D, K(1) and K(2) and TAU Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Theoretical stages 50Column D W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at outlet of CT(2) / bar(abs) 10Pressure in CD(3) / bar(abs) 2.2Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40TAU Pressure at the top / bar(abs) 1Temperature at the top / °C 64.3Pressure at the bottom / bar(abs) 1.2Temperature at the bottom / °C 95.5Number of trays 80Feed to tray 40 Table 8b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from CD(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55f(M(2)) / f(H(2)) 0.40f(T(3)) / f(G) *) 1.0f(P(1)) / f(H(1)) 2.25f(P(2)) / f(H(2)) 1.86Ratios off(waste gas) / f(G) *) < 0.0015mass flow ratesf(T(1)) / f(T(2)) 90of streamsMethanol to CT(1) / Methanol to CT(2) 3.3Methanol to VK(1) / methanol to V(1b) 0.091Methanol to Vk(2) / methanol to V(1b) 0.033f(T(1)) / f(T(4)) 28.8f(Feed to TAU) / f(P(1)) 0.0235Feed ethanol / f (Feed to TAU) 1.68Reflux ratio of TAU 7T(1b.2.2) / T(1b.1) 0.130*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water. P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water. S(1): 21 weight-% of sodium ethoxide in ethanol, <100 ppm of methanol. S(2): methanol, <1000 ppm of ethanol In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the watercontents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According tothis calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1), fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)8.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg8.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg8.3 fMeOH(water) = 0.001 * f(water) (maximum value)8.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water(bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.8.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:8.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg8.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg8.5.3 fH2O(M) = 0.001 * f(M)8.5.4 fH2O(waste gas) = 0 (neglected)Example 6 is based on Example 4 above. Contrary to Example 4, a part of the mixture P(1), re- moved from the column K(1), which comprises NaOMe and methanol is fed into the trans alco- holization unit, preferably into the middle section of the trans alcoholization unit TAU. A stream comprising ethanol, is fed into a bottom reboiler VTAUof the trans alcoholisation unit TAU and therein combined with a part of the bottoms stream removed from TAU and fed into VTAU of TAU, wherein the combined stream is reintroduced into the trans alcoholisation unit TAU. A stream S(2), which comprises MeOH, is removed from the upper section of the trans alcoholisa- tion unit TAU, preferably as top stream, and a stream S(1) comprising NaOEt and enthanol, is removed as bottoms stream from the trans alcoholisation unit TAU.As in Example 4, two streams are prepared from stream T(1b), i.e. streams T(1b.1) and (T1b.2),wherein stream T(1b.1) is conducted as in Example 4. Contrary to Example 4, stream T(1b.2) issplit into 2 steams T(1b.2.1), T(1b.2.2). T(1b.2.1) is again split into two streams, whereinT(1b.2.1) –after splitting into T(1b.2.1.1) and T(1b.2.1.2) is passed as a heating medium through the bottom reboilers VK(1) and VK(2) of reactive distillation columns K(1) and K(2). The resulting condensed streams after VK(1) and VK(2) are combined and fed as condensed stream Tc(1b.2.1) into the third condensate drum CD(3). T(1b.2.2) is fed to the bottoms reboiler of trans alcoholization unit TAU and the condensed stream Tc(1b.2.2) is fed to the third condensate drum CD(3). Using a part of stream T(1b.2), i.e. stream T(1b.2.2), as heating medium for the bottoms reboiler of trans alcoholization unit TAU VTAU allows to operate TAU without need for further external heating medium. Short description of the FiguresFig.1 shows a schematic overview of a process according to the present inventionwherein a vapor phase V comprising methanol is obtained at the top of the rectification columnD. From said vapor phase V, three (dry) methanol streams are prepared, said at least threestreams comprising a vapor stream G and two streams T(1a) and T(1b), wherein initially, from vapor phase V a vapor stream G and a vapor stream T(1) are prepared, followed by preparation of T(1a) and T(1b) from stream T(1). For preparing the streams T(1a) and T(1b), a first com- pression unit CT(1) and a second compression unit CT(2) are employed. At least a part of the stream T(1a) obtained from CT(1) is then passed as a heating medium through an intermediate reboiler V(1a) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1a) and at least a part of the stream T(1b) obtained from CT(2) is passed as a heat- ing medium through a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b). The gas stream G, exhibiting a flow rate f(G), is passed through a compressor CG, and the thus compressed stream is then divided into two compressed streams G(1) and G(2), both having the same composition as G. The stream G(1) exhibits a flow rate f(G(1)), the stream G(2) exhibits a flow rate f(G(2)), wherein f(G(1))+f((G2))=f(G). The compressed stream G(1) is fed into the lower part of reactive distillation column K(1), wherein into the upper part of K(1), a liquid aqueous stream H(1) comprising a dissolved alkali metal hydroxide A(1)OH is fed. A part of the bottoms stream removed from the column K(1) is fed into the reboiler VK(1) of K(1), the other part of the bottoms stream is the mixture P(1) comprising alkali metal methoxide A(1)OMe and methanol. From the top of the column K(1), which is operated without reflux, a gas stream W(1) essentially consisting of methanol and water is removed, wherein W(1) is fed into a lowerpart of the rectification column D. The compressed stream G(2) is then fed into the lower part ofreactive distillation column K(2), wherein into the upper part of K(2), a liquid aqueous stream H(2) comprising a dissolved alkali metal hydroxide A(2)OH is fed. A part of the bottoms stream removed from the column K(2) is fed into the reboiler VK(2) of K(2), the other part of the bottoms stream is the mixture P(2) comprising alkali metal methoxide A(2)OMe and methanol. From the top of the column K(2), which is operated without reflux, a gas stream W(2) essentially consist- ing of methanol and water is removed, wherein W(2) is fed, together with W(1), into a lower part of the rectification column D. The realization of the reflux ratio for rectification column D is shown in the upper part of Fig.1, wherein realizing the reflux ratio comprises preparing from the vapor phase V a further vapor stream T(2), passing said stream T(2) through a condenser V(2), obtaining a liquid stream T(3) and a waste gas stream T(2w), and feeding the liquid stream T(3) into the top of the rectification column D. Additionally, Tc(1a) and / or Tc(1b), preferably Tc(1a) and Tc(1b), each at least partially, is / are fed to a first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in a second condensate drum CD(2) in depressurized form, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the recti- fication column D.Fig.2 shows a schematic overview of a process according to the present inventionwherein a vapor phase V comprising methanol is obtained at the top of the rectification column D. From said vapor phase V, three (dry) methanol streams are prepared, said at least three streams comprising a vapor stream G and two streams T(1a) and T(1b), wherein initially, from vapor phase V a vapor stream G and a vapor stream T(1) are preparing, followed by prepara- tion of T(1a) and T(1b) from stream T(1). For preparing the streams T(1a) and T(1b), a first compression unit CT(1) and a second compression unit CT(2) are employed, wherein stream T(1) is initially fed to the first compression unit CT(1) and the resulting stream after CT(1) is then split into two streams, wherein a first part stream thereof T(1a) is fed a heating medium through an intermediate reboiler V(1a) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1a). A second part stream thereof is fed to the second compres- sion unit CT(2), and at least a part of the stream T(1b) obtained from CT(2) is passed as a heat- ing medium through a bottom reboiler V(1b) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1b). The gas stream G, exhibiting a flow rate f(G), is passed through a compressor CG, and the thus compressed stream is then divided into two compressed streams G(1) and G(2), both having the same composition as G. The stream G(1) exhibits a flow rate f(G(1)), the stream G(2) exhibits a flow rate f(G(2)), wherein f(G(1))+f((G2))=f(G). The compressed stream G(1) is fed into the lower part of reactive distilla- tion column K(1), wherein into the upper part of K(1), a liquid aqueous stream H(1) comprising a dissolved alkali metal hydroxide A(1)OH is fed. A part of the bottoms stream removed from the column K(1) is fed into the reboiler VK(1) of K(1), the other part of the bottoms stream is the mix- ture P(1) comprising alkali metal methoxide A(1)OMe and methanol. From the top of the column K(1), which is operated without reflux, a gas stream W(1) essentially consisting of methanol and water is removed, wherein W(1) is fed into a lower part of the rectification column D. The com- pressed stream G(2) is then fed into the lower part of reactive distillation column K(2), wherein into the upper part of K(2), a liquid aqueous stream H(2) comprising a dissolved alkali metal hy- droxide A(2)OH is fed. A part of the bottoms stream removed from the column K(2) is fed into the reboiler VK(2) of K(2), the other part of the bottoms stream is the mixture P(2) comprising al- kali metal methoxide A(2)OMe and methanol. From the top of the column K(2), which is oper- ated without reflux, a gas stream W(2) essentially consisting of methanol and water is removed, wherein W(2) is fed, together with W(1), into a lower part of the rectification column D. The reali- zation of the reflux ratio for rectification column D is as described in Fig.1 above.Fig.3 shows a schematic overview of a process according to the present invention as inFig.1 with an additional third compression unit CT(3). A vapor phase V comprising methanol is obtained at the top of the rectification column D. From said vapor phase V, four (dry) methanol streams are prepared, said at least four streams comprising vapor stream G, stream T(1a), stream T(1b), and a further stream T(1c), said stream T(1c) having a pressure pT(1c) and a tem- perature TT(1c) with pT(1c) > pV and TT(1c) > TV, Initially, from vapor phase V a vapor stream G and a vapor stream T(1) is prepared, followed by preparation of T(1a) and T(1b) from stream T(1). For preparing the streams T(1a) and T(1b), a first compression unit CT(1) and a second com- pression unit CT(2) are employed, wherein a first part of T(1) is passed through CT(1) obtaining T(1a) and a second part of T(1) is passed through CT(2) obtaining T(1b). At least a part of the stream T(1a) obtained from CT(1) is then passed as a heating medium through an intermediate reboiler V(1a) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1a) and at least a part of the stream T(1b) obtained from CT(2) is passed as a heat- ing medium through a bottom reboiler V(1b) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1b). For preparing the stream T(1c), the third com- pression unit CT(3) is employed, wherein a further part of T(1a) is passed through the third com- pression unit CT(3), obtaining T(1c). At least a part of T(1c) (T(1c.1)) is then passed as a heat- ing medium through reboiler VK(1) of K(1), wherein the stream condensates, thereby obtaining a stream TC(1c.1) at least another part of T(1c) (T(1c.2)) is then passed as a heating medium through reboiler VK(2) of K(2) wherein the stream condensates, thereby obtaining a stream TC(1c.2). The realization of the reflux ratio for rectification column D is as described in Fig.1 above, wherein additionally, TC(1c.1) and TC(1c.2) are combined and fed as TC(1c) into the firstcondendate drum.Fig.4 shows a schematic overview of a process according to the present invention as inFig.2 with an additional third compression unit CT(3). A vapor phase V comprising methanol is obtained at the top of the rectification column D. From said vapor phase V, four (dry) methanol streams are prepared, said at least four streams comprising vapor stream G, stream T(1a), stream T(1b), and a further stream T(1c), said stream T(1c) having a pressure pT(1c)and a tem- perature TT(1c)with pT(1c)> pVand TT(1c)> TV. For preparing the streams T(1a) and T(1b), a first compression unit CT(1) and a second compression unit CT(2) are employed, wherein stream T(1) is initially divided into at least two streams, wherein a first part of stream of T(1) is passed through CT(1), obtaining T(1a), and a second part stream of T(1) is passed through the third compression unit CT(3), obtaining T(1c). T(1a) obtained from CT(1) is divided into at least two streams and a part stream of T(1a) is fed as a heating medium through an intermediate reboiler V(1a) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1a). A second part stream of T(1a) is fed to the second compression unit CT(2), and at least a part of the stream T(1b) obtained from CT(2) is passed as a heating medium through a bottom reboiler V(1b) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1b). At least a part of T(1c) (T(1c.1)) is then passed as a heating medium through reboiler VK(1) of K(1), wherein the stream condensates, thereby obtaining a stream TC(1c.1) at least another part of T(1c) (T(1c.2)) is then passed as a heating medium through reboiler VK(2) of K(2) wherein the stream condensates, thereby obtaining a stream TC(1c.2). The realization of the reflux ratio for rectification column D is as described in Fig.1 above, wherein additionally, TC(1c.1) and TC(1c.2) are combined and fed as TC(1c) into the first condendate drum. Fig.5 shows a schematic overview of a process according to the present invention as in Fig.1 with an additional third compression unit CT(3). A vapor phase V comprising methanol is obtained at the top of the rectification column D. From said vapor phase V, four (dry) methanol streams are prepared, said at least four streams comprising vapor stream G, stream T(1a), stream T(1b), and a further stream T(1c), said stream T(1c) having a pressure pT(1c) and a tem-perature TT(1c) with pT(1c) > pV and TT(1c) > TV, Initially, from vapor phase V a vapor stream G anda vapor stream T(1) is prepared, followed by preparation of T(1a), T(1b) and T(1c) from stream T(1). For preparing the streams T(1a) and T(1b), a first compression unit CT(1) and a second compression unit CT(2) are employed, wherein a first part of T(1) is passed through CT(1) ob- taining T(1a) and a second part of T(1) is passed through CT(2) obtaining T(1b). A third part of T(1) is passed through CT(3) obtaining T(1c). At least a part of the stream T(1a) obtained from CT(1) is then passed as a heating medium through an intermediate reboiler V(1a) of the rectifi- cation column D, wherein the stream condensates, thereby obtaining a stream TC(1a) and at least a part of the stream T(1b) obtained from CT(2) is passed as a heating medium through a bottom reboiler V(1b) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1b). At least a part of T(1c) (T(1c.1)) is then passed as a heating medium through reboiler VK(1) of K(1), wherein the stream condensates, thereby obtaining a stream TC(1c.1) at least another part of T(1c) (T(1c.2)) is then passed as a heating medium through reboiler VK(2) of K(2) wherein the stream condensates, thereby obtaining a stream TC(1c.2). The realization of the reflux ratio for rectification column D is as described in Fig.1 above, wherein additionally, TC(1c.1) and TC(1c.2) are combined and fed as TC(1c) into the first condendate drum.Fig.6 shows a schematic overview of a process according to the present invention as inFig.2 with an additional third compression unit CT(3). A vapor phase V comprising methanol is obtained at the top of the rectification column D. From said vapor phase V, four (dry) methanol streams are prepared, said at least four streams comprising vapor stream G, stream T(1a), stream T(1b), and a further stream T(1c), said stream T(1c) having a pressure pT(1c) and a tem- perature TT(1c)with pT(1c)> pVand TT(1c)> TV. For preparing the streams T(1a), T(1b) and T(1c), a first compression unit CT(1), a second compression unit CT(2), and a third compression unit CT(3) are employed, wherein stream T(1) is initially passed through CT(1), obtaining T(1a). T(1a) is split into at least three part streams, wherein a part stream thereof is fed as a heating medium through an intermediate reboiler V(1a) of the rectification column D, wherein the stream conden- sates, thereby obtaining a stream TC(1a), while another part thereof is passed through CT(2), obtaining T(1b) and still another part thereof is passed through CT(3), obtaining T(1c). At least a part of the stream T(1b) obtained from CT(2) is passed as a heating medium through a bottom reboiler V(1b) of the rectification column D, wherein the stream condensates, thereby obtaining a stream TC(1b). At least a part of T(1c) (T(1c.1)) is then passed as a heating medium through reboiler VK(1) of K(1), wherein the stream condensates, thereby obtaining a stream TC(1c.1) at least another part of T(1c) (T(1c.2)) is then passed as a heating medium through reboiler VK(2) of K(2) wherein the stream condensates, thereby obtaining a stream TC(1c.2). The realization of the reflux ratio for rectification column D is as described in Fig.1 above, wherein additionally, TC(1c.1) and TC(1c.2) are combined and fed as TC(1c) into the first condendate drum.Fig.7 shows a schematic overview of a comparative process, without compression unitsas used in Reference Example 1.Fig.8 shows a schematic overview of a comparative process, with only a first compressionunit CT(1) as used in Reference Example 2.Fig.9 shows a schematic overview of a process according to the present invention as inFig.1 with first and second compression units CT(1), CT(2) and as used in Example 1, supple- mented with methanol addition shown for rectification column D and reactive columns K(1) and K(2) as well as with realization of the reflux ratio for rectification column D as in Fig.1. Contrary to Fig.1, the stream G is not compressed in a compressor CG but rather separated into two streams G(1) and G(2), wherein each of G(1), G(2) is passed through a compressor CG(1), CG(2) before being passed into the respective reactive reactive distillation column K(1), K(2).Fig.10 shows a schematic overview of a process according to the present invention as inFig.1 with first and second compression units CT(1), CT(2) as used in Example 2, supplemented with methanol addition shown for rectification column D and reactive columns K(1) and K(2) as well as with realization of the reflux ratio for rectification column D as in Fig.1. Contrary to Fig. 1, the stream G is not compressed in a compressor CG but rather separated into two streams G(1) and G(2), wherein each of G(1), G(2) is passed through a compressor CG(1), CG(2) before being passed into the respective reactive distillation column K(1), K(2). Furthermore, stream T(1b) from CT(2) is split into two streams, wherein a first part of the stream T(1b) (T(1b.1)) is passed as a heating medium through a bottom reboiler V(1b) of the rectification column D, wherein the stream condensates, thereby obtaining a stream Tc(1b.1) having a temperature TTc(1b.1) with TTc(1b.1) < TT(1b); and a second part of stream T(1b) (T(1b.2)) is, after further division into substreams T(1b.2.1) and T(1b.2.2) passed as a heating medium through the bottom reboil- ers VK(1) and VK(2) of reactive distillation columns K(1) and K(2). The resulting condensed streams after VK(1) and VK(2) are combined and fed as condensed stream Tc(1b.2) into the first condensate drum CD(1), into which also Tc(1a), Tc(1b.1) are fed.Fig.11 shows a schematic overview of a process according to the present invention as inFig.5 with first, second and third compression units CT(1), CT(2) and CT(3) as used in Example 3, supplemented with methanol addition shown for rectification column D and reactive columns K(1) and K(2) as well as with realization of the reflux ratio for rectification column D as de- scribed above. Contrary to Fig.5, the stream G is not compressed in a compressor CG but ra- ther separated into two streams G(1) and G(2), wherein each of G(1), G(2) is passed through a compressor CG(1), CG(2) before being passed into the respective reactive distillation column K(1), K(2). Furthermore, stream T(1c) from CT(3) is divided into two streams T(1c.1) andT(1c.2), wherein T(1c.1) passed as a heating medium through the bottom reboiler VK(1) of reac-tive distillation column K(1) and T(1c.2) is passed as heating medium through the bottom re- boiler VK(2) of reactive distillation column K(2). The resulting condensed streams after VK(1) andVK(2) are combined and fed as condensed stream TC(1c) into the first condensate drum CD(1),into which also Tc(1a), Tc(1b) are fed.Fig.12 shows a schematic overview of a process according to the present invention as inFig.10 with first and second compression units CT(1), CT(2) and as used in Example 4, supple- mented with methanol addition shown for rectification column D and reactive columns K(1) and K(2) as well as with realization of the reflux ratio for rectification column D as in Fig.10. Con- trary to Fig.10 (and to Fig.1), the streams Tc(1b.1) and Tc(1b.2) are not combined with Tc(1a) and fed to CD(1) but are rather fed separately to a third condensation drum CD(3), from which a stream T(4) is obtained and fed into the top of rectification column D and a further stream T(5) is obtained from CD(3), which is fed to CD(2). Tc(1a) is conducted alone as described for Fig.10 and for Fig.1 respectively, i.e. Tc(1a) at least partially, is / are fed to the first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) and with T(5) in a second condensate drum CD(2) in depressurized form, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D.Fig.13 shows a schematic overview of a process according to the present invention as inFig.12 with an additional trans alcoholization unit TAU, wherein three streams are preparedfrom stream T(1b), i.e. streams T(1b.1), (T1b.2) and T(1b.3), wherein streams T(1b.1), (T1b.2) are conducted as in Fig.12, wherein stream (T(1b.2)) is, after further division into sub-streams T(1b.2.1) and T(1b.2.2) passed as a heating medium through the bottom reboilers VK(1) and VK(2) of reactive distillation columns K(1) and K(2). The resulting condensed streams after VK(1) and VK(2) are combined and fed as condensed stream TC(1b.2) into the third condensate drumCD(3). Stream T(1b.3) is fed to the bottoms reboiler of trans alcoholization unit TAU and thecondensed stream Tc(1b.3) is fed to the third condensate drum CD(3). A part of the mixture P(1), removed from the column K(1), which comprises alkali metal methoxide A(1)OMe andmethanol is fed into the trans alcoholization unit TAU, preferably into the middle section of thetrans alcoholization unit TAU. A stream comprising an alcohol XOH, with X being a C2 to C10alkyl group, preferably an ethyl group (XOH = ethanol), is fed into a bottom reboiler VTAU of thetrans alcoholisation unit TAU and therein combined with a part of the bottoms stream removedfrom the TAU and fed into VTAU of TAU, wherein the combined stream is reintroduced into thetrans alcoholisation unit TAU. A stream S(0), which comprises MeOH, is removed from the up-per section of the trans alcoholisation unit TAU, preferably as top stream, and condensed to give a stream S(2), and a stream S(1) comprising alcohol XOH and A(1)OX with X being a C2to C10 alkyl group, preferably A(1)OEt, is removed as bottoms stream from the trans alcoholisa-tion unit TAU.Fig.14 shows a schematic overview of a process according to the present invention as inFig.12 with additional trans alcoholization unit, wherein two streams are prepared from stream T(1b), i.e. streams T(1b.1) and (T1b.2), wherein stream T(1b.1) is conducted as in Fig.12, whilestream T(1b.2) is split into two steams T(1b.2.1) and T(1b.2.2). T(1b.2.1) is, after further divisioninto substreams T(1b.2.1.1) and T(1b.2.1.2) passed as a heating medium through the bottom reboilers VK(1) and VK(2) of reactive distillation columns K(1) and K(2). The resulting condensed streams after VK(1) and VK(2) are combined and fed as condensed stream Tc(1b.2.1) into the third condensate drum CD(3). T(1b.2.2) is fed to the bottoms reboiler of trans alcoholization unit and the condensed stream Tc(1b.2.2) is fed to the third condensate drum CD(3). A part of the mixture P(1), removed from the column K(1), which comprises alkali metal methoxide A(1)OMe and methanol is fed into the trans alcoholization unit, preferably into the middle section of thetrans alcoholization unit. A stream comprising an alcohol XOH, with X being a C2 to C10 alkyl group, preferably an ethyl group (XOH = ethanol), is fed into a bottom reboiler VTAU of the trans alcoholisation unit TAU and therein combined with a part of the bottoms stream removed from the TAU and fed into VTAU of TAU, wherein the combined stream is reintroduced into the trans alcoholisation unit TAU. A stream S(0), which comprises MeOH, is removed from the upper sec- tion of the trans alcoholisation unit TAU, preferably as top stream, and condensed to give a stream S(2), and a stream S(1) comprising alcohol XOH and A(1)OX with X being a C2 to C10 alkyl group, preferably A(1)OEt, is removed as bottoms stream from the trans alcoholisation unit TAU.Fig.15 shows a schematic overview of a process according to the present invention as inFig.12 with additional trans alcoholization unit, wherein two streams are prepared from stream T(1b), i.e. streams T(1b.1) and (T1b.2), wherein stream T(1b.1) is conducted as in Fig.12, while stream T(1b.2) is, after further division into substreams T(1b.2.1) and T(1b.2.2) passed as a heating medium through the bottom reboilers VK(1) and VK(2) of reactive distillation columns K(1) and K(2). The resulting condensed streams after VK(1) and VK(2) are combined and fed ascondensed stream Tc(1b.2) into the third condensate drum CD(3).Furthermore, two streams are prepared from stream T(1a), i.e. streams T(1a.1) and (T1a.2), wherein stream T(1a.1) is conducted as in Fig.12, i.e. passed as a heating medium through the intermediate reboiler V(1a) of D and the resulting stream Tc(1a.1) is fed to the first condensate drum CD(1). T(1a.2) is fed to the bottoms reboiler of trans alcoholization unit and the con-densed stream Tc(1a.2) is fed to the first condensate drum CD(1). A part of the mixture P(1), re-moved from the column K(1), which comprises alkali metal methoxide A(1)OMe and methanol is fed into the trans alcoholization unit, preferably into the middle section of the trans alcoholiza- tion unit. A stream comprising an alcohol XOH, with X being a C2 to C10 alkyl group, preferably an ethyl group (XOH = ethanol), is fed into a bottom reboiler VTAU of the trans alcoholisation unit TAU and therein combined with a part of the bottoms stream removed from the TAU and fed into VTAUof TAU, wherein the combined stream is reintroduced into the trans alcoholisation unit TAU. A stream S(0), which comprises MeOH, is removed from the upper section of the trans al- coholisation unit TAU, preferably as top stream, and condensed to give a stream S(2), and a stream S(1) comprising alcohol XOH and A(1)OX with X being a C2 to C10 alkyl group, prefera- bly A(1)OEt, is removed as bottoms stream from the trans alcoholisation unit TAU.Fig.16 For simplification, the preparation of the at least three streams from the vapor phaseV, said at least three streams comprising a vapor stream G and T(1) and streams T(1a) andT(1b) respectively as well as T(2) is shown in Figures 1 to 15 above in that each of thesestreams G, T(1) and T(2) is taken directly from the top of the rectification column D. However, itis a preferred set-up to take of vapor phase V via a single line from the top of the rectification column D and to take therefrom streams G, T(1) and T(2) via split-of lines. This preferred set-upis schematically shown in Fig.16 and is applicable for each of Figures 1 to 15.Cited Literature -US 2002 / 0183566 A1- US 2008 / 0296786 A1- WO 2013 / 168113 A1- WO 2021 / 148174 A1- WO 2022 / 117803 A1- WO 2022 / 263032 A1

Claims

Claims1. An integrated process for simultaneously preparing n mixtures P(i) comprising alkali metalmethoxide and methanol, comprising providing n reactive distillation columns K(i); providing n aqueous liquid streams H(i), a given stream H(i) comprising a dissolved alkali metal hydroxide A(i)OH, wherein n is an integer with n≥2 and i=1…n; and providing a rectification column D comprising at least one intermediate reboiler V(1a) and at least one bottom reboiler (V1b); providing a first compression unit CT(1), a second compression unit CT(2) and at least one further compression unit CG; wherein the process comprises preparing the one or more alkali metal methoxides in the n reactive distillation column K(i) under reactive distillation conditions from the n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streams W(i) com- prising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further comprising (a) obtaining a vapor phase V comprising methanol at the top of the rectification columnD, said vapor phase V having a pressure pV and a temperature TV; (b) preparing at least three streams from the vapor phase V, said at least three streamscomprising a vapor stream G having a pressure pGand a temperature TGwith pG= pVand TG= TV, and further comprising two streams T(1a) and T(1b), said stream T(1a) having a pressure pT(1a)and a temperature TT(1a)with pT(1a)> pVand TT(1a)> TVand said stream T(1b) having a pressure pT(1b) and a temperature TT(1b) with pT(1b) > pV and TT(1b) > TV, wherein for preparing the streams T(1a) and T(1b), the first com- pression unit CT(1) and the second compression unit CT(2) are employed;(c) preparing n streams G(i) from the vapor stream G, each of the streams G(i) having apressure pG(i)and a temperature TG(i)with pG(i)> pGand TG(i)> TGfor each stream G(i), and feeding each stream G(i) into the respective reactive distillation column K(i), wherein for preparing the n streams G(i), the at least one compression unit CGis employed; (d) passing at least a part of the stream T(1a) as a heating medium through an interme-diate reboiler V(1a) of the rectification column D, obtaining a stream TC(1a) having a temperature TTc(1a)with TTc(1a)< TT(1a); (e) passing at least a part of the stream T(1b) as a heating medium through a bottomreboiler V(1b) of the rectification column D, obtaining a stream TC(1b) having a tem-perature TTc(1b)with TTc(1b)< TT(1b); (f) feeding one or more of(f.1) at least a part of one or more of the top streams W(i),(f.2) at least a part of the stream TC(1a), and(f.3) at least a part of the stream TC(1b)into the rectification column D.

2. The process of claim 1, wherein preparing the at least three streams according to (b) com-prises (b.1) splitting the vapor phase V into at least two vapor streams comprising thestream G and a vapor stream T(1) having a pressure pT(1)and a temperature TT(1)with 0.95 ≤ pT(1) / pV≤ 1.00; (b.2) preparing at least the two streams T(1a) and T(1b) from the vapor streamT(1).

3. The process of claim 2, wherein (b.2) comprises splitting vapor stream T(1) into at leasttwo streams and passing a first part stream of T(1) through the first compression unit CT(1), obtaining T(1a), and passing a second part stream of T(1) through the second com- pression unit CT(2), obtaining T(1b).

4. The process of claim 2, wherein (b.2) comprises passing vapor stream T(1) through thefirst compression unit CT(1), obtaining T(1a); and passing a part of T(1a) through the sec- ond compression unit CT(2), obtaining T(1b).

5. The process of any one of claims 1 to 4, wherein a further stream T(2) is prepared fromthe vapor phase V and said stream T(2) is passed through the condenser V(2), obtaining a liquid stream T(2l) and a gas stream T(2g); wherein the gas stream T(2g) is passed through a condenser V(3), obtaining a liquid stream T(2gl) and a waste gas stream T(2w); and the liquid streams T(2l) and (T2gl) are combined in a second condensate drum CD(2) in depressurized form.

6. The process of any one of claims 1 to 5, whereinTc(1a) at least partially is fed to a first condensate drum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2g) in depressurized form; and Tc(1b) at least partially is fed to a third condensate drum CD(3), wherein from said third condensate drum CD(3) a gaseous stream T(4) is obtained, which is fed into the top of the rectification column D and / or into the vapor phase V and / or into the stream G and / or into the stream T(1), preferably into the top of the rectification column D or into the vaporphase V or into the stream G or into the stream T(1), more preferably into the top of the rectification column D or into the vapor phase V, and from said condensate drum CD(3) further a liquid stream T(5) is obtained, which is fed to the second condensate drum CD(2), wherein T(5) is combined with the liquid streams T(2l) and (T2gl) in CD(2) in de- pressurized form, obtaining a combined liquid stream from the second condensate drum CD(2), which is fed as the stream T(3) into the top of the rectification column D.

7. The process of any one of claims 3 to 6, wherein the n reactive columns K(i) have each areboiler, preferably bottom reboiler, VK(i) and wherein (e) comprises (e.1) passing at least a first part of the stream T(1b) (T(1b.1)) as a heating mediumthrough a bottom reboiler V(1b) of the rectification column D, obtaining a stream TC(1b.1) having a temperature TTc(1b.1)with TTc(1b.1)< TT(1b); (e.2) passing at least a second part of stream T(1b) (T(1b.2)) as a heating mediumthrough at least one bottom reboiler VK(i) of one of the n reactive distillation column K(i), obtaining a stream TC(1b.2) having a temperature TTc(1b.2)with TTc(1b.2)< TT(1b).

8. The process of any one of embodiments 1 to 7, wherein at least one of the n bottomsstreams P(i) comprising alkali metal methoxide A(i)OMe and methanol is at least partially fed to a trans alcoholisation unit TAU, wherein (x) the (part)stream comprising alkali metal methoxide A(i)OMe and methanol is con-tacted in the trans alcoholisation unit TAU with an alcohol HOX, wherein X repre- sents an alkyl residue selected from the group consisting of C2 to C10 alkyl, prefera- bly C2 alkyl, thereby obtaining a stream S(1) comprising alkali metal alkoxide A(i)OX and alcohol XOH and a stream S(2) comprising methanol; (y) removing the stream S(2) comprising methanol from the trans alcoholisation unitTAU, preferably as a liquid stream, more preferably as a liquid top stream; and re- moving the stream S(1) comprising alkali metal alkoxide A(i)OX and alcohol XOH from the trans alcoholisation unit TAU, preferably as a liquid stream, more preferably as a liquid stream from the lower part of TAU, more preferably as a liquid bottoms stream.

9. The process of any one of claims 1 to 8, comprising providing a third compression unitCT(3), wherein (b) comprises preparing at least four streams from the vapor phase V, said at least four streams comprising vapor stream G, stream T(1a), stream T(1b), and a fur- ther stream T(1c), said stream T(1c) having a pressure pT(1c) and a temperature TT(1c) withpT(1c)> pVand TT(1c)> TV, wherein for preparing the stream T(1c), the third compression unit CT(3) is employed.

10. The process of claim 9, wherein the n reactive columns K(i) have each a reboiler, prefera-bly bottom reboiler, VK(i) and wherein at least a part of T(1c) is passed as heating medium through at least one bottom reboiler VK(i) of one of the n reactive distillation column K(i), obtaining a stream TC(1c) having a temperature TTc(1c)with TTc(1c)< TT(1c).

11. The process of any one of claims 1 to 10, wherein a stream T(Di) having a temperatureTT(Di)is taken from the rectification column D at an intermediate position and passed for heating purpose through the intermediate reboiler V(1a) of the rectification column D, ob- taining a heated stream Th(Di) having a temperature TTh(Di) with TTh(Di) > TT(Di), whereinheated stream Th(Di) is reintroduced into rectification column D; and wherein a stream T(Db) having a temperature TT(Db)is taken from the rectification column D at a bottom position and passed for heating purpose through the bottom reboiler V(1b) of the rectification column D, obtaining a stream Th(Db) having a temperature TTh(Db)with TTh(Db) > TT(Db), wherein heated stream Th(Db) is reintroduced into rectification column D; and / or, preferably and; wherein a bottom stream T(Ki) having a temperature TT(Ki)is taken from the bottom of the n reactive columns K(i) and passed for heating purpose through a bottom reboiler VK(i), thereby obtaining a heated stream Th(Ki) having a temperature ThT(Ki)and wherein ThT(Ki)> TT(Ki); wherein heated stream Th(Ki) is reintroduced into rectification column D.

12. The process of any one of claims 1 to 11, further comprising(g) feeding a stream M comprising methanol into the rectification column D at a positionI(M).

13. The process of any one of claims 1 to 12, wherein a stream H(1) comprises dissolved so-dium hydroxide and a stream H(2) comprises dissolved potassium hydroxide, wherein so- dium methoxide is prepared in the reactive distillation column K(1) from which the stream W(1) is obtained and potassium methoxide is prepared in the reactive distillation column K(2) from which the stream W(2) is obtained.

14. The process of any one of claims 1 to 13, wherein (f.1) comprises(f.1.1) feeding at least a part of the top stream W(1) into the lower part of the rectifica-tion column D at a position I(1);(f.1.2) feeding at least a part of the top stream W(2) into the lower part of the rectifica-tion column D at a position I(2), wherein the position I(2) is located below the po- sition I(1); wherein between the positions I(1) and I(2), the rectification column D is equipped with in- ternals.

15. The process of any one of claims 1 to 13, wherein (f) comprises(f.1) feeding at least a part of the top stream W(1) into the lower part of the rectifica-tion column D at a position I(1); (f.2) at least partially condensing at least a part of the top stream W(2), obtaining an atleast partially condensed stream WC(2), and feeding at least a part of the stream WC(2) into the rectification column at a position I(2) (f.3) feeding at least a part of the stream TC(1a) into the rectification column D.

16. The process of claim 15,wherein (f.2’) comprises passing the top stream W(2) having a temperature TW(2)through at least one heat exchanger E, obtaining an at least partially condensed stream WC(2) having a temperature TWC(2) with TWC(2) < TW(2), and feeding at least a part of the at least partially condensed stream WC(2) into the rectification column D at the position I(2); and wherein (g) comprises passing the stream M having a temperature TM1through one or more of said at least one of heat exchangers E, obtaining a stream M having a tempera- ture TM2with TM2> TM1, and feeding the stream M having the temperature TM2into the rec- tification column D at the position I(M); or wherein (f.2) and (g) comprise passing the top stream W(2) having a temperature TW(2) through at least one heat exchanger E(2), obtaining an at least partially, preferably essen- tially completely, condensed stream WC(2) having a temperature TWC(2) with TWC(2) < TW(2); and admixing the stream M, prior to feeding it into the rectification column D at the posi- tion I(M), with at least a part of the stream WC(2), wherein I(M) is preferably above I(1).; or wherein (f.2) and (g) comprise admixing the top stream W(2) having a temperature TW(2) with the stream M having a temperature TM1 with TW(2) > TM1, thereby at least partially, preferably only partially, condensing the stream W(2), and feeding the stream obtained from mixing into the rectification column D at the position I(M), wherein I(M) is preferably above I(1).

17. A chemical production unit for carrying out the process according to any one of claims 1 to16, comprising- a rectification column D comprising-- in its lower part, inlet means for feeding streams W(i) or one or more com-bined stream thereof into D; -- in its upper part, outlet means for removing a vapor stream V or dividedstreams thereof, comprising at least a gaseous stream G and at a stream T(1), from the top of D; -- an intermediate reboiler V(1a);-- a bottom reboiler V(1b);- optionally a stream dividing device So for dividing T(1) into sub streams thereof;- a first compressor CT(1) for compressing T(1) or a part thereof;- a second compressor CT(2) for compressing a part stream of T(1) and / or for com-pressing a compressed sub stream of T(1) or a part thereof; -means for passing compressed sub streams of T(1) from CT(1) and / or CT(2) as heat-ing medium through intermediate reboiler V(1a) and bottom reboiler V(1b); -a stream dividing device S for dividing the stream G into n streams G(i);- means for passing the stream G to said stream dividing device S;- n reactive distillation columns K(i), n≥2 and i=1…n; said reactive distillation columnsK(i) being arranged in parallel, each reactive distillation column K(i) comprising -- in its upper part, preferably in its top, inlet means for feeding a stream H(i) intoK(i); -- in its lower part, inlet means for feeding a stream G(i) into K(i);-- outlet means for removing a stream W(i) from the top of K(i);-- bottom reboilers VK(i);-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms streamremoved from K(i); -means for passing the streams G(i) to the reactive distillation columns K(i);- means for passing the streams W(i) to the rectification column D;- one or more compressors CG(i) for compressing either the stream G and / or thestreams G(i) and / or the streams W(i).

18. Use of a chemical production unit according to claim 17 or of a process according to anyone of claims 1 to 16 for simultaneously producing n mixtures P(i) comprising alkali metalmethoxide and methanol, n being an integer with n≥2 and i=1…n, wherein either at least 2 of the mixtures P(i) comprise different alkali metal methoxides A(i)OMe,and / or at least 2 of the mixtures P(i) comprise the same alkali metal alkoxide A(i)OMe at different concentrations.

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