Process for preparing pseudoionone

Abstract

The invention relates to a process for preparing pseudoionone, comprising: (i) reacting citral and acetone in a reactor in the presence of a lye to give a reaction mixture (1) containing pseudoionone and acetone; (ii) separating the acetone from the reaction mixture (1) by stripping with steam (5), whereby a crude product stream containing pseudoionone and a gas stream (9) containing acetone are obtained; (iii) cooling the gas stream (9) containing acetone, wherein the heat liberated when cooling the gas stream (9) containing acetone is used in a heat pump (15) to produce steam.

Description

Process for the production of pseudoionone Description The invention relates to a process for the preparation of pseudoionone, comprising: (i) reacting citral and acetone in a reactor in the presence of an alkali to form a reaction mixture containing pseudoionone and acetone; (ii) separating the acetone from the reaction mixture by steam stripping to obtain a crude product stream containing pseudoionone and a gas stream containing acetone; (iii) Cooling the acetone-containing gas stream. Pseudoionone is a starting material used primarily for the production of vitamins A and E. To produce pseudoionone, citral is reacted with acetone in the presence of an alkali solution. Acetone, citral, and the alkali solution are mixed and heated to a temperature at which the reaction takes place. Since acetone is added in excess and thus not fully converted in the reaction, it is necessary to separate the unreacted acetone. To do this, the reaction mixture obtained from the reaction of citral with acetone is steam-stripped, yielding a gas stream containing acetone. To reuse the acetone, particularly to recycle it back into the reaction, it is necessary to cool the acetone-containing gas stream to condense the acetone from the gas stream. A process for the preparation of pseudoionone by reacting citral and acetone in the presence of an alkali solution, in which the acetone is separated from the gas stream by stripping with steam, is described, for example, in WO-A 2004 / 041764. DE-A 10359026 discloses a process for the production of tetrahydropseudoionone by aldol condensation of citral with acetone followed by hydrogenation. Furthermore, the use of tetrahydropseudoionone for the production of phytol, isophytol, tocopherol, and tocopherol derivatives is described. Currently, the acetone-containing gas stream is cooled using cooling water, so that the heat contained in the acetone-containing gas stream is lost as waste heat and is not used. The object of the present invention is to provide a process for the production of pseudoionone which can reduce energy consumption and thus also carbon dioxide emissions. The problem is solved by a process for the production of pseudoionone, comprising: (i) reacting citral and acetone in a reactor in the presence of an alkali to form a reaction mixture containing pseudoionone and acetone; (ii) separating the acetone from the reaction mixture by steam stripping to obtain a crude product stream containing pseudoionone and a gas stream containing acetone; (iii) cooling the acetone-containing gas stream, wherein the heat released during cooling of the acetone-containing gas stream is used in a heat pump to generate water vapor. The use of a heat pump makes it possible to effectively utilize the heat released during the cooling of the acetone-containing gas stream. Since steam is also required in many processes, harnessing this heat saves energy that would otherwise be used to generate steam. Since fossil fuels are typically used to provide sufficient energy for steam generation, saving energy also reduces carbon dioxide emissions. In the context of the present invention, a heat pump refers to a device in which a material flow is evaporated and optionally heated in a heat exchanger, and then compressed to a higher pressure and temperature level in a pump or compressor. The material flow can be a circulating temperature control medium that transfers its heat to water in another heat exchanger to generate steam (closed heat pump), or the water is evaporated directly by heat transfer in a heat exchanger and further compressed and heated by compression in a compressor (open heat pump). To produce pseudoionone, in a first step (i), citral is reacted with acetone in a reactor in the presence of an alkali solution to form a reaction mixture containing pseudoionone and acetone. For example, this can be done by first mixing the citral and acetone and heating them to reaction temperature. Before the preheated mixture of citral and acetone is introduced into the reactor, the alkali solution used as a catalyst is with the mixture of citral and acetone. Acetone is usually added in excess and also serves as a solvent. Sodium hydroxide is particularly preferred as the alkali metal hydroxide used as a catalyst. The reactor used to convert acetone and citral to pseudoionone is typically a tubular reactor. The reaction is carried out in a known manner, as described, for example, in WO-A 2004 / 041764. The reaction mixture leaving the reactor, containing pseudoionone and acetone, is first fed to a column for further processing, where the reaction mixture is stripped with steam. In this way, the acetone is largely removed from the reaction mixture, and a crude product containing pseudoionone is obtained. “Largely” here means that as much acetone as technically possible is removed from the reaction mixture. In addition to any acetone still present, the crude product contains unreacted citral, water, and other secondary components. To neutralize the alkali metal hydroxide solution, an acid, preferably an organic acid, in particular acetic acid, is added to the column, so that the neutralization of the alkali metal hydroxide solution with the acid produces the corresponding salt dissolved in water, preferably the corresponding organic alkali metal salt dissolved in water, more preferably alkali metal acetate dissolved in water, in particular sodium acetate. The steam introduced into the column preferably has a temperature in the range of 100 to 200 °C, more preferably in the range of 105 to 160 °C and in particular in the range of 110 to 140 °C and a pressure in the range of 1 to 6 bar(abs), more preferably in the range of 1.2 to 4 bar(abs) and in particular in the range of 1.5 to 2 bar(abs). The steam is usually introduced into the column at the bottom of the column and flows in the column in countercurrent to the reaction mixture introduced into the column via a side inlet. To improve mixing of the reaction mixture and vapor, the column comprises internals, for example structured packing or random packing. In the column, the temperature decreases from bottom to top, so that the vapor fed in largely condenses and flows downwards. The lower-boiling acetone fed in via the reaction mixture is converted into the gas phase, so that an acetone-enriched gas phase is obtained at the top of the column, which is withdrawn from the top of the column as an acetone-containing gas stream. The acetone-containing gas stream preferably has a temperature in the range from 50 to 100 °C, more preferably a temperature in the range from 50 to 80 °C, in particular in the range from 55 to 65 °C, and a pressure in the range from 0 bar(g) to 2 bar(g), more preferably a pressure in the range from 0 to 1 bar(g) and in particular a pressure in the range from 0 to 0.5 bar(g). After withdrawal, the acetone-containing gas stream is cooled at the top of the column, causing the acetone to condense. A portion of the condensed acetone is then recycled to the top of the column. In order to be able to at least partially utilize the heat released during the cooling and condensation of the acetone, this is used according to the invention in a heat pump to generate water vapor. The heat pump can have a closed circuit with a temperature control medium, wherein the acetone releases the heat to a temperature control medium in a first heat exchanger and water is evaporated in a second heat exchanger of the closed circuit. For this purpose, the temperature control medium is evaporated by the heat absorption in the first heat exchanger and then compressed, wherein the temperature control medium is further heated by the compression. In the second heat exchanger, the temperature control medium releases the heat to the water, causing the water to evaporate. After the heat has been released to the water, during which the temperature control medium condenses, the temperature control medium is expanded in an expansion device, for example a throttle or a turbine, cooled in the process and can then again absorb heat from the acetone-containing gas stream in the first heat exchanger, wherein the acetone-containing gas stream is cooled in this way and the acetone is at least partially condensed. Suitable temperature control agents for use in a closed circuit include synthetic temperature control agents such as hydrofluoroolefins, preferably R1336mzz(Z), R1233zd(E), and R1234ze(Z), as well as natural hydrocarbons, preferably R600 (n-butane), R600a (isobutane), and R601 (pentane), as well as inorganic compounds, preferably R717 (ammonia). R600 (n-butane) is particularly preferred as a temperature control agent. Typically, the temperature control medium is evaporated in the first heat exchanger by absorbing heat from the acetone-containing gas stream and heated to a temperature in the range from 30 to 90 °C, more preferably to a temperature in the range from 35 to 70 °C and in particular to a temperature in the range from 40 to 55 °C. In the downstream compressor, the temperature control medium is compressed, depending on the temperature control medium used, such that the temperature of the temperature control medium increases to 100 to 200 °C, more preferably to 115 to 180 °C and in particular to 120 to 160 °C. Due to the heat released when the water evaporates in the second heat exchanger, the temperature control medium condenses and cools to a temperature in the range from 100 to 140 °C, more preferably in the range from 110 to 135 °C and in particular in the range from 120 to 130 °C.In the expansion device, the tempering medium is then expanded again so that the tempering medium cools down to 30 to 90 °C, more preferably to 35 to 70 °C and in particular to 40 to 55 °C. If n-butane is used as a temperature control medium, it usually has a pressure in the range of 2.8 to 12.5 bar(abs), more preferably in the range of 3.2 to 8.1 bar(abs) and in particular in the range from 3.7 to 5.0 bar(abs) and is heated in the first heat exchanger by absorption of heat from the acetone-containing gas stream to a temperature in the range from 30 to 90°C, more preferably to a temperature in the range from 35 to 70°C and in particular to a temperature in the range from 40 to 55°C and evaporated. In the downstream compressor, the n-butane is preferably compressed to a pressure in the range from 15 to 30 bar(abs), more preferably to a pressure in the range from 20 to 28 bar(abs) and in particular to a pressure in the range from 22 to 26 bar(abs), the temperature of the n-butane increasing to 100 to 200°C, more preferably to 115 to 180°C and in particular to 120 to 160°C. Due to the heat release during evaporation of the water in the second heat exchanger, the n-butane cools to a temperature in the range of 100 to 140 °C, more preferably in the range of 110 to 135 °C and in particular in the range of 120 to 130 °C.In the expansion device, the n-butane is then expanded to a pressure in the range of 2.8 to 12.5 bar(abs), more preferably in the range of 3.2 to 8.1 bar(abs) and in particular in the range of 3.7 to 5.0 bar(abs), wherein the temperature of the n-butane cools to 30 to 90 °C, more preferably to 35 to 70 °C and in particular to 40 to 55 °C. The acetone-containing gas stream is cooled in the first heat exchanger by the heat transfer to the temperature control medium, preferably to a temperature in the range from 50 to 95 °C, more preferably in the range from 50 to 80 °C and in particular in the range from 50 to 60 °C, wherein 50 to 100 wt.%, more preferably 80 to 100 wt.% and in particular 90 to 100 wt.% of the acetone condenses. The water supplied to the second heat exchanger preferably has a pressure in the range of 0.9 to 4 bar(abs), more preferably in the range of 1 to 2 bar(abs) and in particular in the range of 1.2 to 1.5 bar(abs) and a temperature in the range of 10 to 99°C, more preferably in the range of 40 to 80°C and in particular in the range of 50 to 70°C. The steam generated in the second heat exchanger preferably has a temperature in the range of 96 to 160°C, more preferably in the range of 99 to 140°C and in particular in the range of 104 to 120°C. Since steam is required for stripping the reaction mixture in the column, it is particularly preferred to use the steam generated in the second heat exchanger for this purpose. Since the amount of steam generated in the second heat exchanger is generally greater than the amount of steam supplied to the column for stripping the reaction mixture, the portion required for stripping is introduced into the column, and the remaining steam can be supplied to other consumers. Alternatively, it is also possible to feed the steam generated in the second heat exchanger to consumers for low-pressure steam and / or to compress it in at least one compressor to medium-pressure steam or high-pressure steam. It is particularly preferred here to feed a portion of the steam to the column and to feed the portion not fed to the column to the To be supplied to consumers for low-pressure steam and / or to be compressed in the at least one compressor to form medium-pressure steam and / or high-pressure steam. To supply the low-pressure steam to the low-pressure steam consumers, it is possible to supply the steam generated in the second heat exchanger directly to the respective consumers. Alternatively, and preferably, the low-pressure steam generated in the second heat exchanger is fed into a low-pressure steam network from which the consumers are supplied. Accordingly, if medium-pressure steam or high-pressure steam is generated by compression, it is also possible to supply the medium-pressure steam or high-pressure steam directly to the corresponding consumers or to feed it into a medium-pressure steam network or high-pressure steam network from which the corresponding consumers are then supplied. In the context of the present invention, low-pressure steam is understood to mean steam which has a pressure in the range from 0.9 to 4 bar(abs), preferably in the range from 1 to 2 bar(abs) and in particular in the range from 1.2 to 1.5 bar(abs) and a temperature in the range from 96 to 160°C, more preferably in the range from 99 to 140°C and in particular in the range from 104 to 120°C. Medium-pressure steam in the context of the present invention is steam with a pressure in the range of 4 to 8 bar(abs), preferably in the range of 4.5 to 7 bar(abs) and in particular in the range of 5 to 6 bar(abs) and a temperature in the range of 143 to 220°C, preferably in the range of 147 to 210°C and in particular in the range of 151 to 200°C. High-pressure steam in the context of the present invention is steam with a pressure in the range of 8 bar(abs) to 40 bar(abs), preferably with a pressure in the range of 10 to 30 bar(abs) and in particular with a pressure in the range of 16 to 20 bar(abs) and a temperature in the range of 170 to 280°C, more preferably in the range of 180 to 260°C and in particular with a temperature in the range of 201 to 240°C. A compressor or a compressor cascade can be used to generate medium-pressure or high-pressure steam, with a compressor cascade comprising at least two compressors in which the steam is compressed in stages being preferred. The compressor cascade also makes it possible, in particular, to first compress the steam to the pressure of medium-pressure steam, extract the portion to be used as medium-pressure steam, and then further compress the remaining steam to high-pressure steam. Particularly preferably, the steam generated in the second heat exchanger is used as low-pressure steam or compressed to medium-pressure steam and then fed into a medium-pressure steam network. As an alternative to the embodiment described above, it is also possible to provide an additional cooling circuit. In this case, the acetone transfers heat to a coolant circulating in the cooling circuit in a fifth heat exchanger. In the first heat exchanger, the coolant then transfers the heat to the temperature control medium in the closed circuit of the heat pump, causing the temperature control medium to evaporate. The cooling circuit with the additional coolant is particularly advantageous when the column condenser and the temperature control medium evaporator are to be installed separately. The column condenser is often located near the top of the column. It is not always structurally possible to place the heat pump in the immediate vicinity of the column head. In this case, the cooling circuit with additional coolant allows the heat pump to be installed on a platform, near the ground, or in an adjacent building. It may happen that fluctuations in the process need to be compensated for, or the amount of steam to be generated fluctuates, and not always the same amount of heat can be removed to cool the acetone-containing gas stream and thus to condense the acetone through steam generation. In this case, the acetone is condensed with the coolant circulating in the cooling circuit, and the coolant transfers the heat absorbed by the acetone to the temperature control medium in the first heat exchanger of the closed-circuit heat pump, while water is evaporated in the second heat exchanger of the closed circuit. To further cool the coolant, the cooling circuit includes an additional heat exchanger downstream of the first heat exchanger. In a further alternative, the closed circuit of the heat pump additionally comprises a flash evaporator in which the temperature control medium partially evaporates, creating a gas phase and a liquid phase. The gas phase is compressed, flows through the second heat exchanger, condenses therein, and is subsequently expanded. The at least partially condensed gas phase is returned to the flash evaporator. The liquid phase is compressed and returned to the first heat exchanger. As a flash evaporator, for example, a vessel can be used which has a lower pressure than the liquid temperature control medium introduced into the vessel. In this case, it is further preferred that the liquid temperature control medium is introduced into the gas phase in the vessel in order to facilitate the evaporation of a portion of the temperature control medium. In order to adjust the pressure in the vessel, the gas phase, after being compressed in the compressor and flowing through the second heat exchanger, is expanded to the desired pressure in an expansion device, for example a throttle. Due to the heat release in the second heat exchanger and the expansion in the expansion device, at least a portion of the temperature control medium usually condenses, which can contribute to a further pressure reduction. Since the cooled and usually at least partially condensed temperature control medium is directly is introduced into the container, a pressure is established in the container which corresponds to the pressure of the cooled and at least partially condensed tempering medium introduced into the container. In addition, the removal of the liquid tempering agent and the pressure increase in the pump ensures that the pressure in the tank is kept at a lower level than the pressure in the circuit through which the liquid tempering agent is passed through the first heat exchanger. The pressure in the flash evaporator is preferably selected such that 0.5 to 30 wt.%, more preferably 1 to 20 wt.%, and in particular 2 to 10 wt.% of the liquid temperature control medium introduced into the flash evaporator evaporates. If the flash evaporator is a vessel, it is further preferred if the proportion of the gas phase in the vessel is in the range of 50 to 90 vol.%, more preferably in the range of 60 to 85 vol.%, and in particular in the range of 70 to 80 vol.%. The pressure to which the temperature control medium is expanded in the flash evaporator is selected depending on the temperature control medium used so that the temperature in the flash evaporator is in the range of 30 to 90 °C, more preferably in the range of 35 to 70 °C and in particular in the range of 40 to 55 °C. In the compressor, the gaseous temperature control medium is preferably compressed to a pressure at which the temperature of the temperature control medium rises to 100 to 200 °C, more preferably in the range of 115 to 180 °C and in particular in the range of 120 to 160 °C. In the expansion device, the temperature control medium is expanded again to the pressure in the container. The liquid tempering agent is compressed in the pump to a pressure that is high enough that the expansion upon entry into the flash evaporator is sufficient to evaporate the desired amount of tempering agent and is still high enough that no tempering agent evaporates in the first heat exchanger. If n-butane is used as a temperature control agent, it is further preferred if the n-butane is expanded in the flash evaporator to a pressure in the range from 2.8 to 12.5 bar(abs), more preferably in the range from 3.2 to 8.1 bar(abs) and in particular in the range from 3.7 to 5.0 bar(abs), so that it has a temperature in the range from 30 to 90 °C, more preferably in the range from 35 to 70 °C and in particular in the range from 40 to 55 °C. In the compressor, the gaseous n-butane is preferably compressed to a pressure in the range of 15 to 30 bar(abs), more preferably in the range of 20 to 28 bar(abs) and in particular in the range of 22 to 26 bar(abs), wherein the temperature of the n-butane rises to 100 to 200 °C, more preferably in the range of 115 to 180 °C and in particular in the range of 120 to 160 °C. In the expansion device, the n-butane is expanded again to the pressure in the container. The liquid n-butane is preferably compressed in the pump to a pressure in the range of 3 to 15 bar(abs), more preferably in the range of 4 to 10 bar(abs) and in particular in the range of 5 to 8 bar(abs), so that the expansion upon entry into the flash evaporator is sufficient to evaporate the desired amount of n-butane and is still high enough that no n-butane evaporates in the first heat exchanger. The use of a flash evaporator increases the proportion of the gas phase of the temperature control medium. Phase separation, which ensures that only the gas phase is fed to the compressor, allows the use of a gas compressor, eliminating the need for a compressor that allows compression of a two-phase mixture. In particular, this prevents liquid temperature control medium from evaporating in the compressor due to the energy supplied, since the entire temperature control medium fed to the compressor is already in gaseous form. Before entering the flash evaporator, the heated temperature transfer medium is completely liquid. As a liquid medium, the temperature transfer medium can be transported over long distances with minimal heat loss. This allows the flash evaporator, and in particular the compressor, to be installed separately from the column condenser, which is typically installed in close proximity to the top of the column. As an alternative to the closed-circuit heat pump described above, it is also possible to generate the steam using an open-circuit heat pump. In this case, heat is transferred from the acetone-containing gas stream to the water to be evaporated in the first heat exchanger. This eliminates the need for an additional closed circuit in which the temperature control medium circulates. Since the acetone-containing gas stream has a temperature which is below the boiling temperature of water at ambient pressure, it is further preferred if the water to be evaporated has a pressure below the ambient pressure, which is further preferably so low that the temperature of the acetone-containing gas stream is higher than the boiling temperature of the water supplied to the first heat exchanger. Preferably, the water to be evaporated has a pressure in the range of 50 to 200 mbar(abs), more preferably a pressure in the range of 80 to 150 mbar(abs) and in particular a pressure in the range of 100 to 120 mbar(abs). Since the pressure at which the water is evaporated and in particular the temperature of the steam is generally too low for use as steam for stripping in the column and also for use in other consumers, it is still preferable to compress the water evaporated in the first heat exchanger to low-pressure steam. At least a portion of the evaporated water compressed to low-pressure steam is then preferably used for stripping in step (ii). Since more steam is generally generated than is required for stripping in step (ii), it is further preferred if at least a portion of the evaporated water compressed to low-pressure steam is supplied to consumers for low-pressure steam and / or is compressed in at least one further compressor to medium-pressure steam or high-pressure steam. It is of course also possible to supply the entire steam to low-pressure steam consumers and / or to compress it into medium-pressure or high-pressure steam in at least one additional compressor. In this case, however, the steam required for stripping must be obtained externally, for example, from a steam network. Therefore, it is preferred if at least part of the steam is used for stripping in step (ii). In a further alternative, it is also possible not to evaporate the water under reduced pressure and then compress it in a compressor, but rather to compress the acetone-containing gas stream, then flow through the first heat exchanger and release heat to the water to be evaporated, and then expand to produce an acetone-containing gas phase and an acetone-containing liquid phase. The gas phase is recycled into the acetone-containing gas stream upstream of the compression, and the liquid phase is either recycled for stripping the reaction mixture or removed from the stripping process. The compression of the acetone-containing gas stream increases the temperature, making it possible to evaporate the water at a pressure that corresponds to the pressure of the low-pressure steam. For this purpose, the acetone-containing gas stream is preferably compressed to a pressure in the range from 4 to 9 bar(abs), more preferably in the range from 5 to 8 bar(abs) and in particular in the range from 6 to 7 bar(abs), so that the temperature of the acetone-containing gas stream rises to 103 to 180 °C, more preferably to 112 to 170 °C and in particular to 120 to 160 °C. Due to the heat release in the first heat exchanger and the subsequent expansion, the temperature of the acetone-containing gas stream decreases and at least part of the acetone condenses. Since, due to fluctuations in the process or due to changing ambient conditions, for example changing ambient temperatures, it is possible, regardless of the type of heat pump used, that the heat released by the acetone-containing gas stream, which is used to produce the steam, is insufficient to at least partially condense the acetone-containing gas stream and cool it to the temperature required for stable operation of the stripping in step (ii) when a portion of the acetone is recycled to the column for stripping the reaction mixture, it is preferred if a fourth heat exchanger is connected downstream of the first heat exchanger, in which the acetone-containing stream can be further cooled. After cooling and condensation, the acetone-containing stream is preferably collected in a container, From this, the required amount can then be withdrawn for return to the column. The portion of acetone not returned to the column can be removed from the stripping process, further processed if necessary, and used for other processes. However, the acetone removed from the stripping process is preferably returned to the reaction for producing the pseudoionone, so that only the portion of the acetone converted during the reaction needs to be added. The water used to generate steam is typically demineralized and degassed water. Any method known to those skilled in the art can be used for demineralization and degassing. The supplied water typically has a temperature in the range of 10 to 99 °C, more preferably in the range of 40 to 80 °C, and especially in the range of 50 to 70 °C. The water can be fed directly to the second heat exchanger using a closed-loop heat pump, or directly to the first heat exchanger using an open-loop heat pump. However, it is preferable for the water to be preheated in a third heat exchanger before being fed to the heat exchanger where the water is evaporated. Preheating reduces the amount of heat required to raise the water temperature to boiling point in the heat exchanger where the water is evaporated, allowing a larger proportion of the transferred heat to be used to evaporate the water. Typically, the water in the third heat exchanger is preheated to a temperature in the range of 30 to 99 °C, more preferably to a temperature in the range of 40 to 80 °C and especially to a temperature in the range of 50 to 70 °C. Each of the heat exchangers used in the process is a heat exchanger for indirect heat transfer to prevent the material flows that release heat from mixing with the material flows that absorb heat. Suitable heat exchangers include, for example, shell-and-tube heat exchangers, plate heat exchangers, spiral heat exchangers, or any other type of heat exchanger for indirect heat transfer known to those skilled in the art. It is possible to construct all heat exchangers with the same design or to use heat exchangers with at least two different designs. Shell-and-tube heat exchangers are preferred if a phase transition occurs on at least one side of the heat exchanger, and plate heat exchangers are preferred if a significant temperature change occurs on both sides of the heat exchanger. The steam generated in the heat pump that is not returned to the stripping column is typically low-pressure steam with a pressure in the range of 0.9 to 4 bar (abs) and can be fed into a low-pressure steam network from which additional consumers are supplied. Alternatively, the steam not returned to the column can be compressed to a higher pressure using a compressor or compressor cascade, and Medium-pressure steam with a pressure in the range of 4 to 8 bar (abs) or high-pressure steam with a pressure of 8 to 40 bar (abs) can be generated, which can then also be fed into corresponding steam networks to which other consumers are connected. Consumers in which the steam can be used include, for example, heat exchangers in which material flows are heated. At an industrial site, this could be, for example, heat exchangers in other production facilities. Furthermore, it is also possible to use the steam to generate hot water for district heating networks. The present invention further relates to a target product which can be obtained or is achievable by a process according to the present invention. In a preferred embodiment, the method, preferably according to one of the above-mentioned embodiments, comprises the step: Conversion of the product of the process, namely pseudoionone, which is obtainable or obtained by any of the above-mentioned embodiments, to obtain the target product. The publication “Chemical Compounds”; Issue 684; paragraphs

[1000] until

[8005] ; ISSN: 2198-4786; published on February 12, 2024 is referred to as Reference RF1, which is incorporated herein by reference in its entirety. Preferably, the target product is a product as defined in Reference RF1 in paragraphs

[1000] to

[8005] . Preferably, the process described here is further a process for producing a product, preferably the target product. The conversion step for obtaining the target product preferably comprises one or more steps as described below and can be carried out by conventional methods known to a person skilled in the art. The conversion step preferably comprises one or more steps of: recycling, preferably depolymerization, gasification, pyrolysis and / or steam cracking; and / or purification, preferably crystallization, (solvent) extraction, distillation, evaporation, hydrotreating, absorption, adsorption and / or treatment with an ion exchanger; and / or fabrication, preferably foaming, synthesis, chemical conversion, polymerization and / or compounding; and / or shaping, preferably foaming, extrusion and / or molding; and / or finishing, preferably coating and / or smoothing. In addition, the one or more steps in Reference RF1 in paragraphs

[1000] to

[8005] described in detail. The term "building block," as used herein, encompasses compounds that exist in a gaseous or liquid state under standard conditions of 0°C and 0.1 MPa. Building blocks are typically used in the chemical industry to form secondary products that have a higher structural complexity and / or a higher molecular weight than the building block on which the secondary product is based. The building block is preferably obtained from the The group consisting of hydrogen, carbon monoxide, carbon dioxide, ethylene oxide, ethylene glycols, synthesis gas consisting of a mixture of hydrogen and carbon monoxide, alkanes, alkenes, alkynes, and aromatic compounds. The alkanes, alkenes, alkynes, and aromatic compounds include, in particular, those having 1 to 12 carbon atoms. The term "monomer," as used herein, encompasses molecules that can react with each other to form polymers through polymerization. The monomer is preferably selected from the group consisting of (meth)acrylic acid, salts of (meth)acrylic acid, especially sodium, potassium, and zinc salts, (meth)acrolein, and (meth)acrylates. (Meth)acrylates having 1 to 22 carbon atoms are preferred, especially those having 1 to 8 carbon atoms. The terms (meth)acrylic acid, (meth)acrolein, or (meth)acrylate refer to acrylic acid, acrolein, or acrylate, respectively, and to methacrylic acid, methacrolein, or methacrylate. Furthermore, the monomer can be selected from hexamethylenediamine (HMD) and adipic acid. The building block can also be an intermediate. The term "intermediate" as used herein encompasses organic reagents used to form compounds of higher molecular complexity. The intermediate can, for example, be selected from the group consisting of phosgene, polyisocyanates, and propylene oxide. The polyisocyanates are, in particular, aromatic di- and polyisocyanates, preferably toluene diisocyanate (TDI) and / or diphenylmethane diisocyanate (MDI). The building block and the monomer, as well as typical conversion steps for obtaining the building block or monomer, are described in paragraphs

[1000] to

[1012] Reference RF1 is described in more detail. The term "Polymer A" as used herein includes thermoplastic polymers, e.g. polyamide or thermoplastic polyurethane, thermosetting polymers, e.g. polyurethane, elastomers, e.g. polybutadiene, or a copolymer or a mixture thereof and is defined in more detail in paragraphs

[2001] until

[2007] the reference RF1 is defined. The term "polymer composition A" as used herein includes all compositions containing a polymer as described above and one or more additives, e.g. reinforcing agents, dyes, modifiers and / or flame retardants, and is defined in more detail in paragraph

[2008] the reference RF1 is defined. The term "polymer product A" as used herein includes a product containing the polymer A and / or the polymer composition A as described above and is defined in more detail in paragraphs

[2009] and

[2010] the reference RF1 is defined. The steps for obtaining the polymer, preferably polymer A, the polymer composition, preferably polymer composition A, or the polymer product, preferably polymer product A, are described in more detail in paragraph

[2011] described in reference RF1. The term "polymer for industrial use" includes rheological polymers, polycarboxylates, alkoxysilated polyalkyleneamines, alkoxysilated polyalkyleneimines, polyether-based polymers, color inhibition and soil removal or cleaning polymers, which are listed in paragraphs

[3035] until

[3044] the reference RF1 is further defined. The term "surfactant for industrial use" includes non-ionic, anionic and amphoteric surfactants for industrial use, which are listed in paragraphs

[3008] until

[3034] of Reference RF1 are further defined. The term "descaling agents for industrial use" includes non-phosphate-based builders (NPB) and phosphonates (CoP) which are described in paragraphs

[3001] until

[3005] Reference RF1 is described in more detail. The term ‘biocide for industrial use’ refers to a chemical compound that kills microorganisms or inhibits their growth or reproduction, as defined in paragraphs

[3006] until

[3007] the reference RF1 is further defined. The term “solvent for industrial use” includes alkylamides, alkyl lactamides, alkyl esters, lactate esters, alkyl diesters, cyclic alkyl diesters, cyclic carbonates, aromatic aldehydes and aromatic esters, which are defined in paragraphs

[3045] until

[3055] the reference RF1 is further defined. The term "dispersants for industrial use" includes anionic and non-ionic dispersants for industrial use, which are listed in paragraphs

[3056] until

[3058] the reference RF1 is further defined. The term "composition and / or formulation thereof" in relation to the polymers for industrial use, surfactants for industrial use, descaling agents for industrial use and / or biocides for industrial use refers to compositions for industrial use and / or products for institutional use and / or textile and household care products and / or personal care products as defined in paragraph

[3059] of reference RF1. The conversion steps for the production of the polymer for industrial use, the surfactant for industrial use, the descaling agent for industrial use and / or the biocide for industrial use are defined in paragraph

[3060] of reference RF1. The conversion steps for producing the composition for industrial use formulation of the polymer for industrial use, the surfactant for industrial use, the descaling agent for industrial use and / or the biocide for industrial use are set out in paragraph

[3061] further defined by reference RF1. The term "plant protection product composition" generally refers to a composition comprising an agrochemically active ingredient and at least one agrochemical formulation additive. Examples of plant protection product compositions, active ingredients, and additives are given in paragraph

[4001] The plant protection product composition can be in any conventional formulation. The plant protection product compositions are prepared in a conventional manner, e.g., as described in the publications by Mollet and Grubemann, Formulation technology, Wiley VCH, Weinheim, 2001; or Knowles, New developments in crop protection product formulation, Agrow Reports DS243, T&F Informa, London, 2005. The conversion steps for producing the agrochemically active ingredients and additives can be carried out analogously to the manufacturing steps for their analogues based on petrochemical or other precursors that are not obtained through recycling processes.In addition, the conversion into compounds mentioned in the sections "Polymer" and "Cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter, other cosmetic ingredients or compositions or formulations thereof" may occur as described in these sections as well as the corresponding paragraphs in Reference RF1. The term "active pharmaceutical ingredients and / or intermediates thereof" encompasses substances that produce a pharmacological effect or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or that affect the structure or function of the body. Intermediates thereof are isolated products formed during a multi-step synthesis route of an active pharmaceutical ingredient. The term "pharmaceutical excipients" includes compounds or mixtures of compounds used in compositions for various pharmaceutical applications that are not themselves substantially pharmaceutically active. Active pharmaceutical ingredients and / or intermediates thereof, as well as pharmaceutical excipients, are defined in paragraph

[5001] as further defined in reference RF1. The conversion steps for the preparation of the active pharmaceutical ingredients and / or intermediates thereof and pharmaceutical excipients may involve one or more synthesis steps and can be carried out using conventional synthesis and techniques known to a person skilled in the art. The terms animal feed additives, food additives for humans and food supplements include vitamins, provitamins and active metabolites thereof, including intermediates and precursors, in particular vitamins A, B, E, D, K and their esters such as acetate, propionate, palmitate esters or alcohols thereof such as retinol or their salts as well as any Combinations thereof; Tetraterpenes, in particular isoprenoids such as carotenoids and xanthophylls, including their intermediates and precursors as well as mixtures and derivatives thereof, in particular beta-carotene, canthaxanthin, citranaxanthin, astaxanthin, zeaxanthin, lutein, lycopene, apo-carotenoids and any combinations thereof; Organic acids, in particular formic acid, propionic acid and their salts such as sodium, calcium or ammonium salts and any combinations thereof, such as, but not limited to, mixtures of formic acid and sodium formate, propionic acid and ammonium propionate, formic acid and propionic acid, formic acid and sodium formate and propionic acid, propionic acid and sodium propionate and formic acid and sodium formate;Glycerides of carboxylic acids and short- and medium-chain fatty acids, conjugated linoleic acids such as omega-6 fatty acid (C18:2) methyl esters and 1,2-propanediol, as well as beverage stabilizers such as polyvinylpyrrolidone polymer or polyvinylimidazole-polyvinylpyrrolidone copolymer. Animal feed additives, human food additives, and food supplements are listed in paragraph ;

[5002] as further defined in Reference RF1. The conversion steps for the production of animal feed additives, human food additives, and food supplements may involve one or more synthesis steps and can be carried out using conventional synthesis and techniques familiar to a person skilled in the art. The term "aroma chemical and aroma composition" encompasses a volatile organic substance with a molecular weight between 70 and 250 g / mol containing a functional group with a carbon backbone of 5 to 16 carbon atoms, including linear, branched, cyclic, for example, with a ring size of C5-C18, bicyclic, or tricyclic aliphatic chains, and not necessarily one or more unsaturated structural elements such as double bonds, triple bonds, aromatics, or heteroaromatics. The one or more additional functional groups are preferably selected from alcohol, ether, ester, ketone, aldehyde, acetal, carboxylic acid, nitrile, thiol, or amine. In one aspect, the aroma chemical is a terpene-based aroma chemical, for example, selected from monoterpenes and monoterpenoids, sesquiterpenes and sesquiterpenoids, diterpenes, triterpenes, or tetraterpenes.Aroma chemicals can be combined with other aroma chemicals to form a flavor composition. Aroma chemicals and flavor compositions are discussed in paragraph .

[5003] as further defined in Reference RF1. The conversion steps for producing the aroma chemical and aroma composition may involve one or more synthesis steps and can be carried out using conventional synthesis and techniques known to a person skilled in the art. The term "aqueous polymer dispersion" includes aqueous compositions containing dispersed polymers and described in section

[6001] as further defined in Reference RF1 entitled "Aqueous Polymer Dispersion." The dispersed polymers can be selected from acrylic emulsion polymers, styrene-acrylic emulsion polymers, styrene-butadiene dispersions, aqueous dispersions with composite particles, acrylate-alkyd hybrid dispersions, polyurethanes (including UV-curable polyurethanes), and polyurethane-poly(meth)acrylate hybrid polymers. The term "emulsion polymer" includes polymers produced by free radical emulsion polymerization. Aqueous polyurethane dispersions are described in section

[6002] Reference RF1 entitled "Polyurethane dispersions" is further defined. UV-curable polyurethanes are defined in section

[6017] Reference RF1. Polyurethane-poly(meth)acrylate hybrid polymers are defined in Section

[6016] the reference RF1 is further defined. The term "polymeric dispersant" preferably includes polymers with a polyether-side chain, in particular polycarboxylate ether polymers and polycondensation products, which are described in paragraph

[6020] of Reference RF1 entitled "Polymeric Dispersant". The conversion (polymerization) steps for the preparation of aqueous polymer dispersions with emulsion polymers are described in Section

[6003] Reference RF1 entitled "Emulsion Polymerization" is further defined. The compositions and uses of aqueous polymer dispersions and polymeric dispersants are further defined in the following sections of Reference RF1: Section

[6004] entitled "Uses of aqueous polymer dispersions", section

[6005] entitled "Binders for architectural and construction coatings", Section

[6006] entitled "Binders for paper coating", Section

[6007] entitled "Binder for fiber bonding", Section

[6008] entitled "Adhesive polymers and adhesive compositions", Section

[6015] entitled "Aqueous polyurethane dispersions for coating compositions", Section

[6016] entitled "Aqueous polyurethane-poly(meth)acrylate hybrid polymers for coating compositions", Section

[6017] entitled "Aqueous UV-curable polyurethane dispersions, their preparation and use, and compositions containing them", Section

[6018] entitled “Inorganic binder compositions with polymeric dispersants and their use”, Section

[6019] entitled "100% curable coating compositions of UV-crosslinkable poly(meth)acrylate and their use for the production of pressure-sensitive self-adhesive articles". Polyisocyanates, compositions containing them and their uses are described in section

[6010] Reference RF1 entitled "Polyisocyanates" is further defined. Hyperbranched polyester polyols and their uses are described in section

[6011] of Reference RF1 entitled "Organic solvent-based hyperbranched polyester polyols for coating compositions". The conversion steps for the preparation of the hyperbranched polyester polyols are described in Section

[6012] the reference RF1 with the title "Production of organic solvent-based hyperbranched polyester polyols" is further defined. Coating compositions containing hyperbranched polyester polyols, polyisocyanates and additives, as well as substrates coated therewith, are described in section

[6013] Reference RF1 entitled "Organic solvent-based two-component coating compositions containing hyperbranched polyester polyols and polyisocyanates" is further defined. Unsaturated polyester polyols, solvent-based coating compositions containing these unsaturated polyester polyols, and substrates for coating with these coating compositions are described in Section

[6018] of Reference RF1 entitled "Organic solvent-based coating compositions containing unsaturated polyester polyols". 100% curable coating compositions are defined in Section

[6019] of Reference RF1 is further defined. Polymer dispersants for inorganic binder compositions are described in section

[6020] of reference RF1 is further defined. Inorganic binder compositions with polymeric dispersants and their use are described in section

[6021] of Reference RF1. The conversion steps for the preparation of the polymeric dispersants are described in Section

[6020] of reference RF1 is further defined. The term "cosmetic surfactant" as used herein includes nonionic, anionic, cationic and amphoteric surfactants and is defined in paragraph

[7002] the reference RF1 is further defined. The term "emollient" as used herein refers to a chemical compound used to protect, moisturize and / or lubricate the skin and is defined in paragraph

[7003] the reference RF1 is further defined. The term "wax" as used here includes pearlescent agents and opacifiers and is defined in paragraph

[7004] the reference RF1 is further defined. The term "cosmetic polymer" as used herein includes any polymer that can be used as a component of a cosmetic formulation and is defined in paragraph

[7005] the reference RF1 is further defined. The term "UV filter" as used here refers to a chemical compound that blocks or absorbs ultraviolet light and is defined in paragraph

[7006] the reference RF1 is further defined. The term "other cosmetic ingredient," as used here, includes any ingredient suitable for the manufacture of a cosmetic formulation. Several sources list cosmetically acceptable ingredients. For example, the Cosing database on the European Commission's website lists cosmetic ingredients, and the International Cosmetic Ingredient Dictionary and Handbook, published by the Personal Care Products Council (PCPC), lists cosmetic ingredients. The term "composition and / or formulation thereof" in relation to the cosmetic surfactant, the emollient, the wax, the cosmetic polymer, the UV filter and / or the other cosmetic ingredient refers to personal care and / or cosmetic compositions or formulations described in paragraph

[7007] of Reference RF1. The conversion steps for the manufacture of the cosmetic surfactant, emollient, wax, cosmetic polymer, UV filter or other cosmetic ingredient are described in paragraph

[7008] the reference RF1 is further defined. The terms "polymer B", "polymer composition B", "coating composition", "further functional composition", "film", "molded body", "coating" and "coated substrate" are known to the person skilled in the art and are defined in paragraphs

[8000] until

[8005] of Reference RF1 is further defined. Embodiments of the invention are illustrated in the figures and are explained in more detail in the following description. They show: Figure 1 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a first embodiment; Figure 2 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a second embodiment; Figure 3 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a third embodiment; Figure 4 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a fourth embodiment; Figure 5 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a fifth embodiment; Figure 6 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a sixth embodiment; Figure 7 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a seventh embodiment; Figure 1 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a first embodiment. A reaction mixture 1 containing pseudoionone and acetone is produced by reacting citral with acetone. For this purpose, citral and acetone are fed to a reactor, for example, a tubular reactor. In the reactor, the citral reacts with acetone in the presence of an alkali metal hydroxide solution, particularly aqueous sodium hydroxide, as a catalyst, to form pseudoionone. Since acetone is used in excess, the reaction mixture produced in the reactor contains acetone in addition to the pseudoionone formed. To obtain pseudoionone as a product, the acetone must be removed from the reaction mixture. To separate acetone, the reaction mixture 1 containing pseudoionone and acetone is fed to a column 3 in which the acetone is removed from the reaction mixture 1 by stripping with steam. For this purpose, steam 5 is fed into the lower region of the column and passed in countercurrent with the reaction mixture 1 in the column 3. For better mixing, the column 3 comprises internals 7, in particular packing. The steam 5 initially rises in the column, condenses in the column and thus assists in the separation of the acetone from the reaction mixture. The acetone fed to the column is converted into the gas phase under the conditions prevailing in the column, so that a gas stream 9 containing acetone is withdrawn at the top of the column. The condensed water, pseudoionone and other components boiling higher than acetone collect as crude product at the bottom 11 of column 3. The crude product can be removed from column 3 via a bottom outlet 13 and fed for further processing. The acetone-containing gas stream 9 taken from the top of column 3 is cooled so that the acetone condenses. According to the invention, the heat released during the cooling of the acetone-containing gas stream is used in a heat pump 15 to generate water vapor. In the embodiment shown in Figure 1, the heat pump 15 comprises a closed circuit 17 with a first heat exchanger 19, in which the acetone-containing gas stream releases heat to a temperature control medium. After heat absorption, the evaporated temperature control medium is compressed in a compressor 21, whereby the temperature of the temperature control medium continues to rise. In a second heat exchanger 23, the temperature control medium releases heat to water, which in the second heat exchanger 23. After the heat has been released in the second heat exchanger 23, the temperature control medium is expanded again in an expansion device 25, for example a throttle, and fed back into the first heat exchanger 19. The water to be evaporated in the second heat exchanger 23 is preferably preheated in a third heat exchanger 27, as shown here. Any material stream having a temperature above the temperature of the water to be heated can be used for preheating. Preferably, a material stream that is otherwise cooled with a coolant is used to preheat the water. In this way, the heat of the material stream can also be utilized and is not lost unused with the coolant. It is particularly preferred if the material stream to be cooled, with which the water is preheated, is a material stream to be cooled from the further processing of the raw product, so that heat integration is achieved in this way. The gas stream containing acetone cooled in the first heat exchanger 19 can be fed to a fourth heat exchanger 29 for further cooling to completely condense the acetone. A conventional coolant, such as cooling water, is used for cooling. The condensed acetone is collected in a container 31, and a portion of the acetone is returned to column 3. A portion can be removed from the stripping process for further use. However, the removed portion is preferably returned to the reaction for producing the pseudoionone. A portion of the steam generated in the heat pump 15 is introduced into the column 3 as steam for stripping. The steam not used for stripping can be fed to a steam network 33 to supply additional consumers. In the embodiment shown in Figure 1, the steam is used at the pressure at which the water was evaporated in the second heat exchanger 23. Typically, the steam generated in the second heat exchanger 23 is low-pressure steam with a pressure in the range of 0.9 to 4 bar (abs), so that the steam network is a low-pressure steam network and the other consumers also use low-pressure steam. Figure 2 shows a process for separating acetone from a reaction mixture containing pseudoionone and acetone in a second embodiment, which differs from the embodiment shown in Figure 1 in that the portion of the vapor generated in the second heat exchanger 23 not returned to column 3 is compressed in at least one compressor 35 to form medium-pressure vapor at a pressure in the range of 4 to 8 bar(abs). It is possible to use only one compressor or, preferably, a compressor cascade. In addition, further water can be injected downstream of each compressor to generate steam. The medium-pressure vapor generated in this way can be supplied to any consumer that uses medium-pressure vapor. By using additional compressors, it is also possible to further compress the steam to a pressure in the range of 8 bar(abs) to 40 bar(abs), so that, depending on other steam-using processes, the process can generate steam that can be used for possible further processes fed via a common steam network. The embodiment shown in Figure 3 differs from the embodiment shown in Figure 2 by an additional circuit 37 upstream of the heat pump 15. A coolant circulates in the additional circuit 37, which absorbs heat from the acetone-containing gas stream in a fifth heat exchanger 39 and transfers the heat to the temperature control medium in the first heat exchanger 19 of the heat pump 15. The additional circuit 37 enables the heat pump 15 to be installed spatially separate from the heat exchanger 39, which is typically installed in the immediate vicinity of column 3. If not all of the heat transferred by the acetone-containing gas stream to the coolant in the additional circuit 37 is used to heat and evaporate the temperature control medium in the first heat exchanger 19 of the heat pump 15, it is possible to arrange a further heat exchanger 41 downstream of the first heat exchanger 19 in the additional cooling circuit 37, in which the coolant is further cooled before entering the fifth heat exchanger 39. Such an embodiment is shown as an example in Figure 4. With the additional heat exchanger 41 in the additional circuit 37, a stable circuit can be achieved and, in particular, any temperature fluctuations that may occur in the additional circuit 37 or in the heat pump 15, which simultaneously lead to a change in heat demand, can be compensated. For example, the amount of steam to be generated can be varied as needed, or process-related temperature fluctuations can be compensated. Another embodiment with a closed heat pump is shown in Figure 5. In the embodiment shown in Figure 5, the heat pump 15 additionally comprises a flash evaporator 43, in which a portion of the temperature control medium of the heat pump circuit, preferably 2 to 10 wt.% of the temperature control medium, evaporates by sudden pressure reduction. The flash evaporator 43 is preferably a container in which a liquid phase and a gas phase form, wherein the evaporation of the portion of the temperature control medium occurs because the pressure in the container is lower than the pressure of the liquid temperature control medium introduced into the container used as the flash evaporator 43, so that the liquid temperature control medium suddenly expands upon entering the flash evaporator and thereby partially evaporates. The evaporated part of the temperature control medium is compressed in the compressor 21, so that its temperature is increased. In the second heat exchanger 23, the temperature control medium releases heat to Evaporation and superheating of the water for steam generation and condenses. The condensed temperature control medium is then expanded in the expansion device 25 and returned to the flash evaporator. The non-evaporated, liquid part of the temperature control medium is compressed in a pump 45 and returned to the first heat exchanger 19. The use of the flash evaporator and the subsequent compression of only the expanded portion of the temperature control medium ensures that only gaseous temperature control medium is fed into the compressor 21, eliminating the need for a compressor that can also compress and convey multiphase flows. The use of the flash evaporator 43 enables the flash evaporator 43, and in particular the compressor 21, to be installed separately from the heat exchanger 19, which is typically installed in the immediate vicinity of the top of column 3. In addition to a closed heat pump, as shown in Figures 1 to 5, it is also possible to use the heat of the acetone-containing gas stream in an open heat pump for steam generation, as shown in Figures 6 and 7. In an open heat pump, the heat of the acetone-containing gas stream in the first heat exchanger 19 is not transferred to a circulating temperature control medium, but the water is heated and evaporated in the first heat exchanger by heat transfer from the acetone-containing gas stream to the water. A method with an open heat pump in a first embodiment is shown in Figure 6. Since the temperature of the acetone-containing gas stream is below the boiling point of water at ambient pressure, the water preheated in the fourth heat exchanger 27, which is fed to the first heat exchanger 19 for evaporation, preferably has a pressure in the range of 50 to 200 mbar(abs). After evaporation in the first heat exchanger 19, the steam is then compressed in the compressor 21 to the pressure desired for the steam network 33. Due to the low pressure at which the water is evaporated in the first heat exchanger 19, it is particularly preferred that the steam network 33 be a low-pressure steam network, so that the steam only needs to be compressed to a pressure in the range of 0.9 to 4 bar(abs). However, it is also possible to further compress the steam to higher pressures using additional compressors in order to be able to feed it, for example, into a medium-pressure steam network or a high-pressure steam network.The portion of steam returned to column 3 is compressed to the pressure required for feeding into column 3, which is a pressure in the low pressure range of 0.9 to 4 bar(abs). In order not to have to expand the water to be evaporated to a pressure below the ambient pressure, as is required for the embodiment shown in Figure 6, it is alternatively also possible, as shown in Figure 7, to compress the acetone-containing gas stream in the compressor 21, wherein this is further heated to a temperature which is sufficient to further heat and evaporate the water flowing through the first heat exchanger 19 and preheated in the fourth heat exchanger 27, wherein the water to be evaporated has a pressure which is sufficiently high to return the steam to the column 3 without further compression and to feed any steam not required into a low-pressure steam network 33. After flowing through the first heat exchanger 19, in which the acetone-containing gas stream preferably at least partially condenses, the at least partially condensed acetone-containing stream can be expanded and completely condensed in an expansion device, for example a throttle, and introduced into a container from which the acetone is partially recycled to the column 3 and partially removed from the stripping process and preferably recycled to the reaction. Alternatively and preferably, the container 31 acts as a flash evaporator, as in the embodiment shown here, so that a portion of the acetone condensed in the first heat exchanger 19 evaporates again and a liquid phase and a gas phase form in the container 31, wherein the gaseous acetone is introduced into the acetone-containing gas stream 9 and the liquid phase is partly withdrawn into the column 3 and partly from the container 31 and preferably returned to the reaction for producing the pseudoionone. In all the embodiments presented here, it is possible to use compressors to bring steam to any pressure level suitable for potential further applications. Thus, in addition to generating low-pressure steam, medium-pressure steam, or high-pressure steam, it is also possible to further divide the steam not introduced into column 3, for example, using part of the steam as low-pressure steam and further compressing another part with a compressor or compressor cascade to supply it as medium-pressure or high-pressure steam to appropriate steam networks and then to appropriate consumers. Examples Example 1 During stripping of the reaction mixture containing pseudoionone and acetone, 1000 kg / h of acetone-containing gas stream at a temperature of 56 °C is withdrawn from the column. In the first heat exchanger of a closed heat pump, 140 kW of heat is transferred from the acetone-containing gas stream to 2000 kg / h of temperature control medium at 5 bar (abs), whereby the acetone-containing stream is cooled to a temperature of 54 °C and condensed. and the tempering medium is heated to a temperature of 51 °C and evaporated. In a compressor with an electrical power consumption of 70 kW, the tempering medium is compressed to a pressure of 21 bar, whereby the temperature rises to 156 °C. In a second heat exchanger of the heat pump, 330 kg / h of water with a temperature of 70 °C and a pressure of 1.5 bar(abs) are heated to 120 °C and evaporated. 160 kg / h of the steam is returned to the column to strip the reaction mixture and the remainder is fed into a low-pressure steam network and made available to various consumers for low-pressure steam. Example 2 Low-pressure steam is generated as in Example 1. However, the low-pressure steam not recycled to the column is not made available to low-pressure steam consumers, but is compressed in a compressor with a power input of 16 kW to a pressure of 5.5 bar (abs), where the temperature rises to 180 °C. Example 3 An additional cooling circuit is installed upstream of the closed-circuit heat pump. Water is used as the coolant in the cooling circuit. In the first heat exchanger, the acetone-containing gas stream (1000 kg / h at a temperature of 56 °C) transfers 140 kW of heat to the water, heating the water to 51 °C. The water transfers the absorbed heat in the first heat exchanger of the cooling circuit to 2250 kg / h of temperature control fluid at 4 bar (abs), heating the fluid to 38 °C and evaporating it. In a compressor with a power consumption of 90 kW, the temperature control fluid is compressed to a pressure of 21 bar (abs), increasing the temperature of the temperature control fluid to 156 °C. In the second heat exchanger, the temperature control medium transfers 230 kW of heat to 350 kg / h of water, which is fed to the second heat exchanger at a temperature of 70 °C and a pressure of 1.5 bar(abs).In the second heat exchanger, the water is heated to 120 °C and evaporated, producing 350 kg / h of steam with a temperature of 120 °C and a pressure of 1.5 bar(abs). Example 4 In the first heat exchanger of an open heat pump, the 1000 kg / h acetone-containing gas stream transfers 140 kW of heat directly to 220 kg / h of water to be evaporated. The water is fed to the heat exchanger at a pressure of 5 bar(abs) and a temperature of 70 °C. In the heat exchanger, the water is expanded and evaporated at 100 mbar(abs) at 46 °C through the absorption of heat. The evaporated water is then compressed in a compressor with a power input of 45 kW to 1.5 bar(abs), during which the temperature rises to 120 °C. 160 kg / h of the steam is returned to the column, which The remainder can be used as low-pressure steam or further compressed into medium-pressure steam or high-pressure steam. Example 5 In contrast to the previous examples, the 1000 kg / h acetone-containing gas stream is first mixed with 390 kg / h recirculated gaseous acetone and then compressed to 5.8 bar(abs) in a compressor with a power input of 50 kW, whereby the temperature rises to 130 °C. In the first heat exchanger, the acetone-containing gas stream gives off 200 kW of heat to 300 kg / h water, whereby the water has a temperature of 70 °C and a pressure of 1.5 bar(abs) upon entering the heat exchanger. In the heat exchanger, the water is heated to 112 °C and evaporated. 160 kg / h of the steam generated can be fed directly back to the column for stripping, the remainder is either fed to other consumers or compressed to medium-pressure steam or high-pressure steam. Due to the release of heat, the acetone-containing gas stream condenses at least partially and is then fed to a flash evaporator.The 390 kg / h of recycled gaseous acetone are removed from the flash evaporator. The liquid acetone is removed and partly returned to the column as reflux and partly used in the reaction to produce pseudoionone.

Claims

Patent claims 1 . A process for producing pseudoionone, comprising: (I) reacting citral and acetone in a reactor in the presence of an alkali metal hydroxide solution to form a reaction mixture (1) containing pseudoionone and acetone; (ii) separating the acetone from the reaction mixture (1) by stripping with steam (5), whereby a crude product stream containing pseudoionone and a gas stream (9) containing acetone are obtained; (iii) cooling the acetone-containing gas stream (9), characterized in that the heat released during cooling of the acetone-containing gas stream (9) is used in a heat pump (15) to generate water vapor.

2. Method according to claim 1, characterized in that the heat pump (15) has a closed circuit (17) and the acetone transfers the heat to a temperature control medium in a first heat exchanger (19) and water is evaporated in a second heat exchanger (23) of the closed circuit (17).

3. A process according to claim 2, characterized in that a portion of the steam generated in the second heat exchanger (23) is used as steam for stripping in step (ii).

4. Method according to claim 2 or 3, characterized in that at least a part of the steam generated in the second heat exchanger (23) is supplied to consumers for low-pressure steam and / or is compressed in at least one compressor (35) to medium-pressure steam and / or high-pressure steam.

5. The method according to claim 1, characterized in that the acetone is cooled with a coolant circulating in a cooling circuit (37), the coolant releases the heat absorbed by the acetone to a temperature control medium in a first heat exchanger (19) of the heat pump (15) with a closed circuit (17) and water is evaporated in a second heat exchanger (23) of the closed circuit, the cooling circuit (37) comprising a further heat exchanger (41) for further cooling the coolant downstream of the first heat exchanger (19) in the flow direction.

6. Method according to one of claims 2 to 4, characterized in that the closed circuit (17) of the heat pump (15) comprises a flash evaporator (43) in in which the temperature control medium is partially evaporated so that a gas phase and a liquid phase are generated, wherein the gas phase is compressed, flows through the second heat exchanger (23), is then expanded, wherein at least a part of the gas phase condenses, and the at least partially condensed gas phase is returned to the flash evaporator (43), and wherein the liquid phase is compressed and returned to the first heat exchanger (19).

7. The method according to claim 1, characterized in that the heat pump (15) is an open heat pump, wherein heat is transferred from the acetone-containing gas stream (9) in the first heat exchanger (19) to water to be evaporated.

8. Process according to claim 7, characterized in that the water to be evaporated has a pressure in the range of 50 to 200 mbar(abs).

9. A process according to claim 8, characterized in that the evaporated water is compressed to low-pressure steam and at least a portion of the evaporated water is used for stripping in step (ii).

10. The method according to claim 9, characterized in that at least a portion of the evaporated water compressed to low-pressure steam is supplied to consumers for low-pressure steam and / or is compressed in at least one further compressor to medium-pressure steam or high-pressure steam. 11 . Process according to claim 7, characterized in that the acetone-containing gas stream is compressed, then flows through the first heat exchanger (19) and releases heat to the water to be evaporated and is subsequently expanded, whereby an acetone-containing gas phase and an acetone-containing liquid phase are generated, wherein the gas phase is recycled into the acetone-containing gas stream (9) upstream of the compression and the liquid phase is recycled into the reaction in step (i) or removed from the process.

12. The method according to any one of claims 1 to 11, characterized in that the water is preheated in a third heat exchanger (27) before being fed to the heat exchanger (19; 23) in which the water is evaporated, wherein the water in the third heat exchanger (27) is preferably preheated to a temperature in the range of 30 to 99 °C.

13. Process according to one of claims 1 to 12, characterized in that the acetone-containing gas stream has a temperature in the range of 56 to 92 °C and a pressure in the range of 0 bar(g) to 2 bar(g) before cooling in step (iii).

14. The method according to any one of claims 4, 9 or 10, characterized in that the low-pressure steam has a pressure in the range from 0.9 bar(abs) to 4 bar(abs) and a temperature in the range from 96 to 160 °C and / or the medium-pressure steam has a pressure in the range from 4 bar(abs) to 8 bar(abs) and a temperature in the range from 143 to 200 °C and / or the high-pressure steam has a pressure in the range from 8 bar(abs) to 40 bar(abs) and a temperature in the range from 170 to 280 °C.

15. A process for producing a target product by converting pseudoionone, comprising: (a) producing pseudoionone by a process according to any one of claims 1 to 14, (b) Conversion of the pseudoionone into the target product.

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