An alcohol conversion process

Abstract

The present invention relates to an alcohol conversion process wherein a homogenous transition metal catalyst is used. In the process, a mixture of alcohols is employed as starting materials to produce medium sized bio-alcohols, in particular propanol and isobutanol, with increased productivities.

Description

[0001] An alcohol conversion process

[0002] The present invention relates to an alcohol conversion process.

[0003] A commonly used industrial production of alcohols is mainly based on an oxo process. Said process comprises the reaction of an alkene with oxo gas, which is a mixture of hydrogen and carbon monoxide in a 1 :1 molar ratio. The reaction is followed by hydrogenation of the aldehyde into the desired alcohol.

[0004] An alternative process for the synthesis of alcohols is based on the Guerbet reaction, which is known for many decades (M. Guerbet, C. R. Hebd. Seances Acad. Sci. 1899, 128, p. SUSIS). It is generally accepted that the mechanism leading to Guerbet alcohols comprises the following three steps: (i) dehydrogenation of a primary alcohol to the respective aldehyde; (ii) aldol condensation of two aldehyde molecules to an o,p-unsaturated aldehyde with elimination of water; and (iii) hydrogenation of the unsaturated aldehyde to the dimer alcohol. An alkaline catalyst, e.g. sodium or potassium hydroxide or sodium or potassium alkoxides, is required for the Guerbet reaction. Often homogeneous or hetereogeneous metal catalysts are added to accelerate the dehydrogenation and hydrogenation steps. However, the Guerbet reaction generally suffers from harsh conditions, poor selectivity, separation issues and low yield.

[0005] In the chemical industry, 1-butanol is an important intermediate product and solvent for a broad variety of products, including paints and various plastics. Up to now, 1-butanol is produced from a petro-based feedstock, leading to a significant product carbon footprint for 1-butanol and the resulting products. Therefore, it is important for the chemical industry to find and open an economical and sustainable process route to butanol with a lower product carbon footprint.

[0006] Ethanol may be a sustainable feedstock to produce chemicals. Using ethanol in the Guerbet reaction may be a profitable and sustainable approach to produce 1-butanol. Whereas the Guerbet reaction is used up to date to produce higher alcohols from higher boiling alcohol feedstocks than ethanol, there is so far no industrial usage for the Guerbet reaction for ethanol as the feedstock to produce 1-butanol. While the Guerbet reaction itself may seem a simple chemical reaction, employing ethanol as the feedstock causes inherent problems particularly concerning selectivity. Because the product, 1-butanol, can itself also undergo dehydrogenation, higher alcohols often result as side products in the process, making the reaction so far not profitable on an industrial scale.

[0007] Efficient production of medium sized bio-alcohols, in particular propanol and isobutanol, is up to date very challenging. It has been proposed to industrially employ fermentation, which however disadvantageously has a very low space / time yield and frequently suffers from low selectivity. This results in a very energy intensive purification. WO 2013 / 156399 A1 relates to a method for producing branched alcohols using at least one alcohol of formula R1-CH2-CH2-OH, the groups R1being different or the same and being selected from C2-C3 alkyl, linear or branched, in a homogeneous phase in the presence of at least one base, characterized in that at least one complex compound containing Ru(ll) is used, in which the Ru(ll) has at least one ligand L1, which is at least bidentate, at least one coordination site of L1being a nitrogen atom.

[0008] A.Kaithal et al., “Ruthenium(ll)-Catalyzed P-Methylation of Alcohols using Methanol as C1 Source”, CHEMCATCHEM, vol. 11 , no. 21 , 2019-05-16, pages 5287 to 5291 , relates to the selective introduction of methyl branches into the carbon chains of alcohols with low loadings of ruthenium precatalyst [RuH(CO)(BH4)(HN(C2H4PPh2)2)] (Ru-MACHO-BH) using methanol both as methylating reagent and as reaction medium.

[0009] US 2015 / 246863 A1 relates to the synthesis of long chain Guerbet alcohols, and in particular to the synthesis of mixtures of Guerbet alcohols containing long-chain multi-branched Guerbet alcohols.

[0010] N. Biswas et al., “Acridine-Based SNS-Ruthenium Pincer Complex-Catalyzed Borrowing Hydrogen-Mediated C-C Alkylation Reaction: Application to the Guerbet Reaction”, SYNLETT, vol. 34, no. 06, 2022-07-08, pages 622 to 628, relates to a study of SNS-based ruthenium pincer catalysts which were applied in a Guerbet condensation reaction of primary alcohols to give 0-alkyiated dimeric alcohols.

[0011] Y.Xie et al., “Highly efficient Process for Production of Biofuel from Ethanol Catalyzed by Ruthenium Pincer Complexes”, Journal of the American Society, vol. 138, no. 29, 2016-07- 18, pages 9077 to 9080, relates to a ruthenium pincer-catalyzed Guerbet-type process for the production of biofuel from ethanol.

[0012] WO 2012 / 119928 A1 relates to a method for producing alkanol amines which comprise a primary amino group and a hydroxyl group, by alcohol amination of diols comprising two hydroxyl groups, using ammonia, and elimination of water.

[0013] US 2010 / 298613 A1 discloses a process of producing an alcohol which comprises dimerizing a starting-material alcohol having 4 or less carbon atoms in an environment having a partial hydrogen pressure of 0.1 MPa or higher.

[0014] So far, catalytic routes for the production of medium sized bio-alcohols is only of academic nature and thus these processes are not industrially feasible, for example due to unsolved problems such as low catalyst stability, low space / time yield and / or troublesome purification.

[0015] Therefore, it was an object of the present invention to provide an alcohol conversion process allowing a profitable and sustainable approach to produce medium sized bio-alcohols with increased productivities. The present invention thus relates to an alcohol conversion process based on the Guerbet reaction, wherein a homogenous transition metal catalyst is used. The process employs a mixture of alcohols as starting materials, allowing a profitable and sustainable approach to produce medium sized alcohols such as isobutanol, 1 -propanol and 1 -butanol with increased productivities. The ratio of the obtained alcohols can effectively be controlled with the ratio of the starting alcohols. Ideally, bio-butanol can be obtained with increased productivities.

[0016] The present invention in particular relates to an alcohol conversion process, comprising

[0017] (I) providing a component C which is at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor;

[0018] (ii) preparing a liquid mixture MEcomprising at least one alcohol Ra-CH2-CH2-OH, at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc- CH2-OH, a base, and the component C provided according to (i), Ra, Rband Rcbeing independently from each other selected from the group consisting of H and Ci-C4-alkyl; wherein Ra-CH2-CH2-OH, Rb-CH2-CH2-OH and Rc-CH2-OH are different from each other;

[0019] (Hi) subjecting the liquid mixture ME prepared according to (ii) to alcohol conversion conditions in a reaction space SGand obtaining in SGa reaction mixture MGcomprising at least one alcohol selected from the group consisting of Rb-CH2- CH2-(CHRa-CH2)x-OH, Ra-CH2-CH2-(CHRb-CH2)x-OH and Rc-CH2-(CHRa-CH2)x- OH, x being an integer in the range of from 1 to 4, wherein the alcohol conversion conditions comprise a temperature of the reaction mixture MGin the range of from 100 to 250 °C and a pressure in the reaction space SGin the range of from 1 x 105to 4 x 106Pa;

[0020] (iv) separating at least one alcohol selected from the group consisting of Rb-CH2- CH2-(CHRa-CH2)x-OH, Ra-CH2-CH2-(CHRb-CH2)x-OH and Rc-CH2-(CHRa-CH2)x- OH from the reaction mixture MGobtained according to (iii), obtaining a mixture Mcs! wherein

[0021] (a) the base is selected from the group consisting of ammonium hydroxide, alkali hydroxides, alkaline earth hydroxides, ammonium carbonate, ammonium hydrogen carbonate, alkali carbonates, alkali hydrogen carbonates, alkaline earth carbonates, alkaline hydrogen carbonates, alkali alkoxides, alkaline earth alkoxides, alkali amides, alkaline earth amides, alkali metal 2, 2,6,6- tetramethylpiperidines, alkaline earth metal 2,2,6,6-tetramethylpiperidines, secondary amino acids, and a mixture of two or more thereof;

[0022] (b) the catalyst comprises a compound of formula (A)

[0023] wherein

[0024] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0025] L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, S(=O)Rg, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRdRe, SbRdRe, and a N-heterocyclic carbene represented by the structures:

[0026] L3is selected from the group consisting of CO, PRdReRf, AsRdReRf, SbRdReRf, SRdRe, RsCN, RsNC, N2, PF3, pyridine, and thiophene;

[0027] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the compound of formula (A) a quinolinyl unit; n is 0 or 1 ;

[0028] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, OH, OR, NRS2, NH3, NRg3, and Rg2NSO2Rg;

[0029] Rd, Re, Rf, Rg, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted C1-C1 o-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3-Cio-cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C5-Cio-aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and unsubstituted or substituted C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2and Ci-Cio-alkyl; and

[0030] X is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C-i-C-io-alkyl; and

[0031] (c) the precursor of the catalyst comprising a compound of formula (A) comprises a mixture comprising 1 ) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cycloalkyl, C2- Ci2-alkenyl, C3-Ci5-cycloalkenyl, C5-C20-aryl, CN, CO, OH, OC(=O)CF3, OSO2CF3, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H)

[0032] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0033] L1and L2, are, independently of each other, PRdRe, NRdRe, SRd, SH, S(=O)Rs, C5-Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRdRe, SbRdRe, and a N-heterocyclic carbene represented by the structures:

[0034] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;

[0035] Rd, Re, Rf, Rg, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-Cio-cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-Cio-aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and unsubstituted or substituted Cs-Cw-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2and Ci-C-io-alkyl; and

[0036] X is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl.

[0037] The process in accordance with the present invention is preferably a continuous process. Alternatively, the process is preferably a semi-batch process or a batch process.

[0038] Preferably, from 90 to 100 weight-%, more preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture MEprepared according to (ii) consist of the at least one alcohol Ra-CH2-CH2-OH, at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc-CH2-OH, the base, and the component C.

[0039] It is preferred that the reaction space SG according to (iii) comprises the reaction mixture MG and a gas phase, wherein the gas phase comprises at least one inert gas, wherein the at least one inert gas is more preferably selected from the group consisting of nitrogen, argon, and a mixture thereof.

[0040] In the process in accordance with the present invention, the alcohol conversion conditions according to (iii) preferably comprise a pressure in the reaction space SGin the range of from 1 x 105to 3.5 x 106Pa, more preferably in the range of from 1 x 105to 3.1 x 106Pa, more preferably in the range in the range of from 1 x 105to 2 x 106Pa, more preferably in the range in the range from 1 x 105to 1.5 x 106Pa. Also, the alcohol conversion conditions according to (iii) preferably comprise a temperature of the reaction mixture MG in the range of from 100 to 200 °C, more preferably in the range of from 120 to 180 °C, more preferably in the range of from 130 to 160 °C.

[0041] Preferably, the alcohol conversion conditions according to (iii) comprise an amount of the base in the reaction mixture MG in the range of from 0.1 to 10 weight-%, more preferably in the range of from 0.5 to 8 weight-%, more preferably in the range of from 1 to 5 weight-%, based on the total weight of the reaction mixture MG.

[0042] It is preferred that the alcohol conversion conditions according to (iii) comprise an amount of component C in the reaction mixture MG in the range of from 0.001 to 2 weight-%, more preferably in the range of from 0.001 to 1 weight-%, more preferably in the range of from 0.001 to 0.5 weight-%, based on the total weight of the reaction mixture MG. In another preferred embodiment, the reaction space SG according to (iii) comprises the reaction mixture MGand a gas phase, wherein the gas phase comprises H2, and wherein the alcohol conversion conditions according to (iii) comprise maintaining the H2partial pressure of the gas phase in the range of from 2 x 104to 3.1 x 106Pa, more preferably in the range of from 2 x 104to 1 .1 x 106Pa, more preferably in the range of from 2 x 104to 6 x 105Pa.

[0043] The H2partial pressure of the gas phase is preferably maintained by introducing H2into the gas phase. Also, the H2partial pressure of the gas phase is preferably maintained by relaxation of the gas phase, more preferably by removing at least a part of H2from the gas phase.

[0044] “Maintaining” the H2partial pressure of the gas phase in the sense of the present invention includes ensuring that the H2partial pressure is within the desired range during the reaction. In case the H2partial pressure is within the desired range, no active steps have to be carried out mandatorily, but the pressure may still be adjusted to a different part of the range if desired. However, in order to ensure that the H2partial pressure is neither too high nor too low, the H2partial pressure may preferably be adjusted, or must be adjusted in case of ensuring that the H2partial pressure is maintained within the desired range, for example by relaxation of the gas phase, in which case the H2partial pressure may be reduced, or, alternatively, by introducing H2into the gas phase, in which case the H2partial pressure may be increased. Depending upon the H2partial pressure during the reaction, one or even both of said alternatives may be carried out if desired to adjust the H2partial pressure and to maintain the H2partial pressure within the desired pressure range at all times during the reaction.

[0045] The pressure during can be monitored by, for example, determination of the overall pressure and comparison to the starting pressure. As hydrogen tends to build up during the reaction, the H2partial pressure changes, e.g. increases, resulting in the pressure to increase over time. For example, by actively measuring and controlling the overall pressure during the reaction, it may be ensured that the H2partial pressure is within the claimed range. If the overall pressure built up is too high, this tends to be at least in part the result of the H2partial pressure increasing. By relaxation of the gas phase, hydrogen can be removed from the gas phase and the H2partial pressure can be maintained in the desired range. Thus, in one preferred embodiment, the H2partial pressure of the gas phase is preferably maintained in the respective range by monitoring the overall pressure of the reaction and adjusting the overall pressure if required, preferably by relaxation of the gas phase, in which case the H2partial pressure may be reduced, or, alternatively, by introducing H2into the gas phase, in which case the H2partial pressure may be increased.

[0046] Alternatively, the hydrogen partial pressure can be determined by other means, such as taking samples of the gas phase during the reaction and analyzing same. As another alternative, the pressure may be monitored via online measurement, and adjusted accordingly as outlined above. It is preferred that the component C comprises a mixture, wherein said mixture comprises: 1 ) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, organic carbonyl compounds, Ci- C -alkyl, C3-Ci2-cycloalkyl, C2-Ci2-alkenyl, Cs-Cis-cycloalkenyl, Cs-C2o-aryl, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H’) wherein M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru; L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, and S(=O)Rg; L3is selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0047] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst comprising a compound of formula (A) an acridinyl unit; n is 0 or 1 , and if R1, R2, R3and R4are hydrogen, n is 0;

[0048] Rd, Re, Rfand Rg, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted C3- Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cw-alkyl; C3-Ci0-heterocycle comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C-io-aryl; and Cs-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0049] Preferably, the component C comprises a compound comprising a metal M selected from the group consisting of lrCI3x H2O, [lr(COD)CI]2, [lr(COE)2CI]2, [lr(C2H4)2CI]2, [lr(COD)OH]2, [lr(COD)MeO]2, [lrCp*CI2], [lrCpCI2], lr4(CO)i2, [lr(PPh3)2(CO)CI], [lr(acetylacetonate)3], and [lr(acetylacetonate)(COD)], wherein Cp is cyclopentadienyl, Cp* is pentamethylcyclopentadienyl, COD is 1 ,5-cyclooctadienyl, COE is cyclooctenyl, and methylallyl is 2-methylallyl. Alternatively, the component C preferably comprises a compound comprising a metal M selected from the group consisting of [Ru(p-cymene)CI2]2, [Ru(benzene)CI2]y, [Ru(CO)2CI2]y, where y is in each case in the range from 1 to 1000, [RU(CO)3CI2]2, [Ru(COD)(allyl)], RuCI3x H2O, [Ru(acetylacetonate)3], [Ru(DMSO)4CI2], [Ru(cyclopentadienyl)(CO)2CI], [Ru(cyclopentadienyl)(CO)2H], [Ru(cyclopentadienyl)(CO)2]2, [Ru(Cp)(CO)2CI], [Ru(Cp*)(CO)2H], [Ru(Cp*)(CO)2]2, [Ru(indenyl)(CO)2CI], [Ru(indenyl)(CO)2H], [Ru(indenyl)(CO)2]2, ruthenocene, [Ru(COD)CI2]2, [Ru(Cp*)(COD)CI], [RU3(CO)I2], [Ru(PPh3)4(H)2], [Ru(PPh3)3(CI)2], [Ru(PPh3)3(CO)(CI)2], [Ru(PPh3)3(CO)(CI)(H)], [Ru(PPhs)3(CO)(H)2], and [Ru(cyclooctadienyl)(methylallyl)2], wherein Cp is cyclopentadienyl, Cp* is pentamethylcyclopentadienyl, COD is 1 , 5-cyclooctadienyl, and methylallyl is 2- methylallyl.

[0050] Preferably, the reduced form of the precursor comprises a compound of formula (P-l) or (P- II): wherein R1, R2, R3and R4either are hydrogen, or form together with the N-containing ring a tetrahydroquinoline unit, a decahydroquinoline unit, a tetrahydroacridine unit, or a tetradecahydroacridine unit; and wherein L1and L2are, independently of each other, as defined above; wherein R1, R2, R3and R4are hydrogen; and wherein L1and L2are, independently of each other, as defined above.

[0051] More preferred is that the reduced form of the precursor comprises a compound of formula (P-l): wherein R1, R2, R3and R4either are hydrogen, or form together with the N-containing ring a tetrahydroacridine unit, or a tetradecahydroacridine unit.

[0052] In another more preferred embodiment, the reduced form of the precursor comprises a compound of formula (P-l I): wherein R1, R2, R3and R4are hydrogen; and wherein L1and L2are, independently of each other, as defined above.

[0053] Preferably, the component C comprises a compound of formula (A’) wherein M, R1, R2, R3and R4, L1, L2, L3, Y and n are as defined above.

[0054] In another preferred embodiment, the component C comprises a compound of formula (B) wherein

[0055] M is selected from the group consisting of Ir, Ru, and Mn;

[0056] L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, and S(=O)Ra;

[0057] L3is selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0058] Rd, Re, Rfand Rg, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C -alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted C3- Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cw-alkyl; C3-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; C5-Cio-aryl; and C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH. Also preferred is that the component C comprises a compound of formula (C) wherein

[0059] M is selected from the group consisting of Ir, Ru, and Mn;

[0060] L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, and S(=O)Rg;

[0061] L3is selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0062] Rd, Re, Rfand Rg, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3- Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; C3-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; C5-Ci0-aryl; and C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0063] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0064] M is preferably selected from the group consisting of Ir and Ru, and more preferably M is Ru.

[0065] L3is preferably CO.

[0066] Preferably, L1and L2are each (PRdRe), and wherein Rdand Reare C1-C1 o-alkyl, more preferably wherein Rdand Reare each isopropyl or tert-butyl. Alternatively, L1and L2are preferably each (PRdRe), and wherein Rdand Reare C3-Cio-cycloalkyl, more preferably wherein Rdand Reare each cyclohexyl. Alternatively, L1and L2are each (PRdRe), and wherein Rdand Reare Cs-Cio-aryL

[0067] Y is preferably selected from the group consisting of F, Cl, Br, and I, more preferably Y is selected from the group consisting of Cl or Br, more preferably Y is Cl. It is also preferred that Y is CO.

[0068] Preferably, the component C comprises a compound of formula (D)

[0069]

[0070] Also preferred is that the component C comprises a reduced form of the catalyst of formula (D’) wherein Cy is cyclohexyl.

[0071] It is furthermore preferred that the component C comprises a compound of formula (E) wherein iPr is isopropyl.

[0072] Also preferred is that the component C comprises a reduced form of the catalyst of formula (E’) wherein iPr is isopropyl.

[0073] It is moreover preferred that the component C comprises a compound of formula (F) wherein tBu is tert-butyl.

[0074] Preferably, the component C comprises a reduced form of the catalyst of formula (F’) wherein tBu is tert-butyl.

[0075] Integer x is preferably 1 or 2, more preferably integer x is 1.

[0076] Preferably, Ra, Rband Rcare independently from each other selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl, preferably from the group consisting of H, methyl, ethyl, propyl, and isopropyl, more preferably from the group consisting of H, ethyl, and propyl, wherein more preferably at least one of Ra, Rband Rcis H, more preferably wherein Raand Rcis H.

[0077] In a preferred embodiment, the liquid mixture ME prepared according to (ii) further comprises a compound of formula (G) or a reduced form thereof (G), wherein R1, R2, R3and R4, L1, L2, and n as defined above. In a more preferred embodiment, R1, R2, R3and R4, L1, L2, and n of the compound of formula (G) or a reduced form thereof are identical to R1, R2, R3and R4, L1, L2, and n of the at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor of the component C. In the liquid mixture ME prepared according to (ii) and subjected to alcohol conversion conditions according to (iii), the molar ratio of the compound of formula (G) or a reduced form thereof relative to the component C is more preferably in the range of from 1 :1 to 10:1 , more preferably in the range of from 1 .02:1 to 8:1 , more preferably in the range from 1 .05:1 to 5:1 . Preferably, the compound of formula (G) or a reduced form thereof is selected from the group consisting of dicyclohexyl-[[5-(dicyclohexylphosphanylmethyl)acridin-4- yl]methyl]phosphane, diisopropyl-[[5-(diisopropylphosphanylmethyl)acridin-4- yl]methyl]phosphane, dicyclohexyl-[[5-(dicyclohexylphosphanylmethyl)pyridin-4- yl]methyl]phosphane and diisopropyl-[[5-(diisopropylphosphanylmethyl)pyridin-4- yl]methyl]phosphane, more preferably wherein the compound of formula (G) or a reduced form thereof is cyclohexyl-[[5-(dicyclohexylphosphanylmethyl)acridin-4-yl]methyl]phosphane or diisopropyl-[[5-(diisopropylphosphanylmethyl)acridin-4-yl]methyl]phosphane.

[0078] Preferably, the base is selected from the group consisting of alkali hydroxides, alkali alkoxides, and a mixture of two or more thereof. The alkali hydroxide is preferably selected from the group consisting of NaOH, KOH, and a mixture thereof, more preferably wherein the alkali hydroxide is KOH. The alkali alkoxide is preferably selected from the group consisting of sodium alkoxides, potassium alkoxides, and a mixture of two or more thereof, more preferably from the group consisting of sodium ethoxide, potassium ethoxide, and a mixture thereof.

[0079] The at least one of the at least one alcohol Ra-CH2-CH2-OH and at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc-CH2-OH is preferably a bio-based alcohol, more preferably obtainable or obtained from sugar-containing crops, more preferably from one or more of sugar cane and corn.

[0080] The liquid mixture ME according to (ii) further preferably comprises a solvent component which comprises one or more solvents. More preferably, the one or more solvents of the solvent component have a boiling point at 1 atm (101325 Pa) of 140 °C or more, more preferably a boiling point of 160 °C or more, more preferably a boiling point of 180 °C or more, more preferably a boiling point of 190 °C or more.

[0081] In a further preferred embodiment, at 25 °C, the solvent component has a solubility in water in the range of from 0 to 0.5 weight-%, more preferably in the range of from 0 to 0.1 weight- %, more preferably a solubility in water at 25 °C of from 0 to 0.05 weight-%, more preferably a solubility in water at 25 °C of from 0 to 0.01 weight-%, based on 100 weight-% water. Also preferred is that the distribution coefficient of the catalyst in a system of the solvent component and water is from 0 to 0.01 , more preferably from 0 to 0.005, more preferably from 0 to 0.005, based on 1 kg catalyst.

[0082] In a more preferred embodiment, the solvent component comprises at least two solvents with a boiling point at 1 atm (101325 Pa) of 180 °C or more.

[0083] In a preferred embodiment, the solvent component comprises at least one solvent selected from the group consisting of biphenyl, diphenyl ether, 1-tert-butyl-3,5-dimethyl-benzene, xylene, mesitylene, toluene, ethylbenzene, cycloedodecane, cyclononane, cyclooctane, cycloheptane, decaline, n-butylbutyrate, n-hexylhexyrate, n-octyloctyrate, texanole, di-n- butylether, di-iso-butylether, di-sec-butylether, and a mixture of two or more thereof, more preferably from the group of biphenyl, diphenyl ether, 1-tert-butyl-3,5-dimethyl-benzene, ethylbenzene, cycloedodecane, cyclononane, cyclooctane, cycloheptane, decaline, n- butylbutyrate, n-hexylhexyrate, n-octyloctyrate, texanole, di-n-butylether, di-iso-butylether, di- sec-butylether, and a mixture of two or more thereof, more preferably from the group consisting of biphenyl, diphenyl ether, and a mixture thereof, wherein more preferably, the solvent is a mixture of biphenyl and diphenyl ether.

[0084] In another preferred embodiment, the solvent is a mixture of at least two aromatic hydrocarbons with a boiling point of 180 °C or more. The solvent is preferably selected from the group consisting of biphenyl, diphenyl ether, 1-tert-butyl-3,5-dimethyl-benzene, ethylbenzene, cyclododecane, cyclononane, cyclooctane, cycloheptane, decaline, n- butylbutyrate, n-hexylhexyrate, n-octyloctyrate, texanole, di-n-butylether, di-iso-butylether, di- sec-butylether, and a mixture of two or more thereof, preferably from the group consisting of biphenyl, diphenyl ether, and a mixture thereof, wherein more preferably, the solvent is a mixture of biphenyl and diphenyl ether.

[0085] In a preferred embodiment, the solvent does not include any one of benzene, toluene, xylene or mesitylene.

[0086] Preferably, the solvent does not form an azeotrope with water. An azeotrope or a constant heating point mixture is a mixture of two or more components in fluidic states whose proportions cannot be altered or changed by simple distillation. This happens because when an azeotrope is boiled, the vapour has the same proportions of constituents as the unboiled mixture. Each azeotrope has a characteristic boiling point. It is not possible to separate the components by fractional distillation.

[0087] In a more preferred embodiment, the solvent component comprises a mixture of biphenyl and diphenyl ether at a molar ratio of biphenyl relative to diphenyl ether in the range of from 1 :2 to 1 :6, preferably in the range of from 1 :2.5 to 1 :4.

[0088] Preferably, from 90 to 100 weight-%, more preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture MEprepared according to (ii) consist of the at least one alcohol Ra-CH2-CH2-OH, the at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc-CH2-OH, the base, the solvent component and the catalyst.

[0089] The alcohol conversion conditions according to (iii) preferably comprise an amount of the solvent in the reaction mixture MGin the range of from 5 to 50 weight-%, more preferably in the range of from 5 to 30 weight-%, more preferably in the range of from 5 to 10 weight-%, based on the total weight of the reaction mixture MG. The mixture Mcs obtained according to (iv) preferably comprises the component C and further comprises the solvent component.

[0090] Preferably, the liquid reaction mixture MGobtained according to (ill) further comprises at least one unreacted alcohol selected from the group consisting of Ra-CH2-CH2-OH, Rb-CH2-CH2- OH and Rc-CH2-OH, the process further comprising separating at least a part of said unreacted alcohol from the liquid reaction mixture MG. More preferred is that separating at least a part of the unreacted alcohol from MG is carried out by one or more of distillation, extraction, flashing, and membrane separation. Also more preferred is that at least a part of the at least one unreacted alcohol separated from MGis recycled to (ii) or (iii).

[0091] The process in accordance with the present invention preferably further comprises (v) recycling at least a part of the mixture Mcs obtained according to (iv) to (ii) or (iii); even more preferred is that the at least part of the mixture Mcs recycled in (v) comprises at least a part of the component C. Also more preferred is that the at least part of the mixture Mcs recycled in (v) comprises at least a part of the component C and at least a part of the solvent component.

[0092] The process in accordance with the present invention preferably further comprises (v) recycling at least a part of the mixture Mcs obtained according to (iv) to (ii) or (iii) by separating the solvent component and recycling the separated solvent component as part of the liquid mixture MEor the reaction mixture MGto (ii) or (iii).

[0093] In a preferred embodiment, the reaction space SRis comprised in a reactor vessel, wherein the reactor vessel is more preferably a complete-mixing reactor vessel. Even more preferred is that the reactor vessel is selected from the group consisting of a stirred tank reactor, a fixed bed reactor, a mobile bed reactor, and a fluidized bed reactor.

[0094] The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instance where a range of embodiments is mentioned, for example in the context of a term such as "The 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 process of any one of embodiments 1 , 2, 3 and 4". Further, it is explicitly noted that the following set of embodiments represents a suitably structured part of the general description directed to preferred aspects of the present invention, and, thus, suitably supports, but does not represent the claims of the present invention.

[0095] 1 . An alcohol conversion process, comprising

[0096] (I) providing a component C which is at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor; (ii) preparing a liquid mixture ME comprising at least one alcohol Ra-CH2-CH2-OH, at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc- CH2-OH, a base, and the component C provided according to (i), Ra, Rband Rcbeing independently from each other selected from the group consisting of H and Ci-C4-alkyl; wherein Ra-CH2-CH2-OH, Rb-CH2-CH2-OH and Rc-CH2-OH are different from each other;

[0097] (iii) subjecting the liquid mixture MEprepared according to (ii) to alcohol conversion conditions in a reaction space SG and obtaining in SG a reaction mixture MG comprising at least one alcohol selected from the group consisting of Rb-CH2- CH2-(CHRa-CH2)x-OH, Ra-CH2-CH2-(CHRb-CH2)x-OH and Rc-CH2-(CHRa-CH2)x- OH, x being an integer in the range of from 1 to 4, wherein the alcohol conversion conditions comprise a temperature of the reaction mixture MGin the range of from 100 to 250 °C and a pressure in the reaction space SG in the range of from 1 x 105to 4 x 106Pa;

[0098] (iv) separating at least one alcohol selected from the group consisting of Rb-CH2- CH2-(CHRa-CH2)x-OH, Ra-CH2-CH2-(CHRb-CH2)x-OH and Rc-CH2-(CHRa-CH2)x- OH from the reaction mixture MGobtained according to (iii), obtaining a mixture Mcs! wherein

[0099] (a) the base is selected from the group consisting of ammonium hydroxide, alkali hydroxides, alkaline earth hydroxides, ammonium carbonate, ammonium hydrogen carbonate, alkali carbonates, alkali hydrogen carbonates, alkaline earth carbonates, alkaline hydrogen carbonates, alkali alkoxides, alkaline earth alkoxides, alkali amides, alkaline earth amides, alkali metal 2, 2,6,6- tetramethylpiperidines, alkaline earth metal 2,2,6,6-tetramethylpiperidines, secondary amino acids, and a mixture of two or more thereof;

[0100] (b) the catalyst comprises a compound of formula (A) wherein

[0101] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0102] L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, S(=O)Ra, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRdRe, SbRdRe, and a N-heterocyclic carbene represented by the structures:

[0103] L3is selected from the group consisting of CO, PRdReRf, AsRdReRf, SbRdReRf, SRdRe, RgCN, RgNC, N2, PF3, pyridine, and thiophene;

[0104] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the compound of formula (A) a quinolinyl unit; n is 0 or 1 ;

[0105] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, OH, OR, NRS2, NH3, NRg3, and Rg2NSO2R9;

[0106] Rd, Re, Rf, Rs, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3-Cio-cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-Cio-aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and unsubstituted or substituted C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2and Ci-Cio-alkyl; and

[0107] X is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and

[0108] (c) the precursor of the catalyst comprising a compound of formula (A) comprises a mixture comprising 1 ) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cycloalkyl, C2- Ci2-alkenyl, C3-Ci5-cycloalkenyl, C5-C20-aryl, CN, CO, OH, OC(=O)CF3, OSO2CF3, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H)

[0109] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0110] L1and L2, are, independently of each other, PRdRe, NRdRe, SRd, SH, S(=O)Rs, Cs-Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRdRe, SbRdRe, and a N-heterocyclic carbene represented by the structures:

[0111] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;

[0112] Rd, Re, Rf, Rg, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C-io-alkyl; unsubstituted or substituted Cs-Cio-cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C-io-alkyl; unsubstituted or substituted Cs-Cio-aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and unsubstituted or substituted Cs-Cw-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2and Ci-C-io-alkyl; and

[0113] X is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl. rocess of embodiment 1 , being a continuous process. The process of embodiment 1 , being a semi-batch process or a batch process. The process of any one of embodiments 1 to 3, wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol Ra-CH2-CH2-OH, at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc-CH2-OH, the base, and the component C. The process of any one of embodiments 1 to 4, wherein the reaction space SGaccording to (ill) comprises the reaction mixture MGand a gas phase, wherein the gas phase comprises at least one inert gas, wherein the at least one inert gas is preferably selected from the group consisting of nitrogen, argon, and a mixture thereof. The process of any one of embodiments 1 to 5, wherein the alcohol conversion conditions according to (ill) comprise a pressure in the reaction space SGin the range of from 1 x 105to 3.5 x 106Pa, preferably in the range of from 1 x 105to 3.1 x 105Pa, more preferably in the range in the range of from 1 x 105to 2 x 106Pa, more preferably in the range in the range from 1 x 105to 1 .5 x 106Pa. The process of any one of embodiments 1 to 6, wherein the alcohol conversion conditions according to (iii) comprise a temperature of the reaction mixture MGin the range of from 100 to 200 °C, preferably in the range of from 120 to 180 °C, more preferably in the range of from 130 to 160 °C. The process of any one of embodiments 1 to 7, wherein the alcohol conversion conditions according to (iii) comprise an amount of the base in the reaction mixture MGin the range of from 0.1 to 10 weight-%, preferably in the range of from 0.5 to 8 weight- %, more preferably in the range of from 1 to 5 weight-%, based on the total weight of the reaction mixture MG. The process of any one of embodiments 1 to 8, wherein the alcohol conversion conditions according to (iii) comprise an amount of component C in the reaction mixture MGin the range of from 0.001 to 2 weight-%, preferably in the range of from 0.001 to 1 weight-%, more preferably in the range of from 0.001 to 0.5 weight-%, based on the total weight of the reaction mixture MG. The process of any one of embodiments 1 to 9, wherein the reaction space SGaccording to (iii) comprises the reaction mixture MGand a gas phase, wherein the gas phase comprises H2, and wherein the alcohol conversion conditions according to (iii) comprise maintaining the H2partial pressure of the gas phase in the range of from 2 x 104to 3.1 x 106Pa, preferably in the range of from 2 x 104to 1 .1 x 106Pa, more preferably in the range of from 2 x 104to 6 x 105Pa. The process of embodiment 10, wherein the H2partial pressure of the gas phase is maintained by introducing H2into the gas phase. The process of embodiment 10 or 11 , wherein the H2partial pressure of the gas phase is maintained by relaxation of the gas phase, preferably by removing at least a part of H2from the gas phase. The process of any one of embodiments 10 to 12, wherein the H2partial pressure of the gas phase is maintained by monitoring the overall pressure during the reaction, preferably by monitoring and, if required, adjusting the overall pressure of the gas phase, more preferably by adjusting the overall pressure of the gas phase by relaxation of the gas phase and / or by introducing H2into the gas phase. The process of any one of embodiments 10 to 12, wherein the H2partial pressure of the gas phase is maintained by taking samples of the gas phase during the reaction and analyzing same, and, if required, by preferably adjusting the overall pressure of the gas phase, more preferably by adjusting the overall pressure of the gas phase by relaxation of the gas phase and / or by introducing H2into the gas phase. The process of any one of embodiments 1 to 14, wherein the component C comprises a mixture, wherein said mixture comprises: 1) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, organic carbonyl compounds, Ci-C-io-alkyl, C3-Ci2-cycloalkyl, C2- Ci2-alkenyl, C3-Ci5-cycloalkenyl, Cs-C2o-aryl, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H’) wherein M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0114] L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, and S(=O)Rg;

[0115] L3is selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0116] R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst comprising a compound of formula (A) an acridinyl unit; n is 0 or 1 , and if R1, R2, R3and R4are hydrogen, n is 0;

[0117] Rd, Re, Rfand Rg, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted C3-Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; C3-Cio-heterocycle comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-Cio-aryl; and C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0118] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH. The process of any one of embodiments 1 to 14, wherein the component C comprises a compound comprising a metal M selected from the group consisting of I rCI3x H2O, [lr(COD)CI]2, [lr(COE)2CI]2, [lr(C2H4)2CI]2, [lr(COD)OH]2, [lr(COD)MeO]2, [lrCp*CI2], [lrCpCI2], lr4(CO)i2, [lr(PPh3)2(CO)CI], [lr(acetylacetonate)3], and [lr(acetylacetonate)(COD)], wherein Cp is cyclopentadienyl, Cp* is pentamethylcyclopentadienyl, COD is 1 ,5-cyclooctadienyl, COE is cyclooctenyl, and methylallyl is 2-methylallyl. The process of any one of embodiments 1 to 14, wherein the component C comprises a compound comprising a metal M selected from the group consisting of [Ru(p- cymene)CI2]2, [Ru(benzene)CI2]y, [Ru(CO)2CI2]y, where y is in each case in the range from 1 to 1000, [Ru(CO)3CI2]2, [Ru(COD)(allyl)], RuCI3x H2O, [Ru(acetylacetonate)3], [Ru(DMSO)4CI2], [Ru(cyclopentadienyl)(CO)2CI], [Ru(cyclopentadienyl)(CO)2H], [Ru(cyclopentadienyl)(CO)2]2, [Ru(Cp)(CO)2CI], [Ru(Cp*)(CO)2H], [Ru(Cp*)(CO)2]2, [Ru(indenyl)(CO)2CI], [Ru(indenyl)(CO)2H], [Ru(indenyl)(CO)2]2, ruthenocene, [RU(COD)CI2]2, [Ru(Cp*)(COD)CI], [RU3(CO)I2], [Ru(PPh3)4(H)2], [Ru(PPh3)3(CI)2], [Ru(PPh3)3(CO)(CI)2], [Ru(PPh3)3(CO)(CI)(H)], [Ru(PPh3)3(CO)(H)2], and [Ru(cyclooctadienyl)(methylallyl)2], wherein Cp is cyclopentadienyl, Cp* is pentamethylcyclopentadienyl, COD is 1 , 5-cyclooctadienyl, and methylallyl is 2- methylallyl. The process of any one of embodiments 1 to 14, wherein the component C comprises a compound of formula (B) wherein

[0119] M is selected from the group consisting of Ir, Ru, and Mn;

[0120] L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, and S(=O)R9; L3is selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0121] Rd, Re, Rfand Rg, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3-Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; C3-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-Cio-aryl; and C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0122] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0123] The process of any one of embodiments 1 to 14, wherein the component C comprises a compound of formula (C) wherein

[0124] M is selected from the group consisting of Ir, Ru, and Mn;

[0125] L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, and S(=O)Rg;

[0126] L3is selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0127] Rd, Re, Rfand Rg, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3-Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; C3-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-Cio-aryl; and C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0128] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0129] The process of any one of embodiments 1 to 14, 18 and 19, wherein M is selected from the group consisting of Ir and Ru, wherein M is preferably Ru.

[0130] The process of any one of embodiments 1 to 14, 18 and 19, wherein L3is CO. The process of any one of embodiments 1 to 14, and 18 to 21 , wherein L1and L2are each (PRdRe), and wherein Rdand Reare Ci-C -alkyl, preferably wherein Rdand Reare each isopropyl or tert-butyl. The process of any one of embodiments 1 to 14, and 17 to 21 , wherein L1and L2are each (PRdRe), and wherein Rdand Reare C3-Cio-cycloalkyl, preferably wherein Rdand Reare each cyclohexyl. The process of any one of embodiments 1 to 14, and 18 to 21 , wherein L1and L2are each (PRdRe), and wherein Rdand Reare C5-Cio-aryl. The process of any one of embodiments 1 to 14, and 18 to 24, wherein Y is selected from the group consisting of F, Cl, Br, and I, preferably from the group consisting of Cl or Br, more preferably wherein Y is Cl. The process of any one of embodiments 1 to 14, and 18 to 24, wherein Y is CO. The process of any one of embodiments 1 to 14, wherein the component C comprises a compound of formula (D) The process of any one of embodiments 1 to 14 and 27, wherein the component C comprises a reduced form of the catalyst of formula (D’) wherein Cy is cyclohexyl. The process of any one of embodiments 1 to 14, wherein the component C comprises a compound of formula (E)

[0131] wherein iPr is isopropyl. The process of any one of embodiments 1 to 14 and 29, wherein the component C comprises a reduced form of the catalyst of formula (E’) wherein iPr is isopropyl. The process of any one of embodiments 1 to 14, wherein the component C comprises a compound of formula (F) wherein tBu is tert-butyl. The process of any one of embodiments 1 to 14 and 31 , wherein the component C comprises a reduced form of the catalyst of formula (F’) wherein tBu is tert-butyl. The process of any one of embodiments 1 to 32, wherein the reduced form of the precursor comprises a compound of formula (P-l) or (P-l I): wherein R1, R2, R3and R4either are hydrogen, or form together with the N-containing ring a tetrahydroquinoline unit, a decahydroquinoline unit, a tetrahydroacridine unit, or a tetradecahydroacridine unit; and wherein L1and L2are, independently of each other, as defined above; wherein R1, R2, R3and R4are hydrogen; and wherein L1and L2are, independently of each other, as defined above. The process of any one of embodiments 1 to 32, wherein the reduced form of the precursor comprises a compound of formula (P-l): wherein R1, R2, R3and R4either are hydrogen, or form together with the N-containing ring a tetrahydroacridine unit, or a tetradecahydroacridine unit. The process of any one of embodiments 1 to 32, wherein the reduced form of the precursor comprises a compound of formula (P-ll): wherein R1, R2, R3and R4are hydrogen; and wherein L1and L2are, independently of each other, as defined above. The process of any one of embodiments 1 to 35, wherein integer x is 1 or 2, preferably wherein integer x is 1. The process of any one of embodiments 1 to 36, wherein Ra, Rband Rcare independently from each other selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and tert-butyl, preferably from the group consisting of H, methyl, ethyl, propyl, and isopropyl, more preferably from the group consisting of H, ethyl, and propyl, wherein more preferably at least one of Ra, Rband Rcis H, more preferably wherein Raand Rcis H. The process of any one of embodiments 1 to 37, wherein the liquid mixture ME prepared according to (ii) further comprises a compound of formula (G) or a reduced form thereof wherein R1, R2, R3and R4, L1, L2, and n as defined above. The process of embodiment 38, wherein R1, R2, R3and R4, L1, L2, and n of the compound of formula (G) or a reduced form thereof are identical to R1, R2, R3and R4, L1, L2, and n of the at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor of the component C. The process of embodiment 38 or 39, wherein in the liquid mixture MEprepared according to (ii) and subjected to alcohol conversion conditions according to (iii), the molar ratio of the compound of formula (G) or a reduced form thereof relative to the component C is in the range of from 1 : 1 to 10: 1 , preferably in the range of from 1 .02: 1 to 8:1 , more preferably in the range from 1.05:1 to 5:1. The process of any one of embodiments 38 to 40, wherein the compound of formula (G) or a reduced form thereof is selected from the group consisting of dicyclohexyl-[[5- (dicyclohexylphosphanylmethyl)acridin-4-yl]methyl]phosphane, diisopropyl-[[5- (diisopropylphosphanylmethyl)acridin-4-yl]methyl]phosphane, dicyclohexyl-[[5- (dicyclohexylphosphanylmethyl)pyridin-4-yl]methyl]phosphane and diisopropyl-[[5- (diisopropylphosphanylmethyl)pyridin-4-yl]methyl]phosphane, preferably wherein the compound of formula (G) or a reduced form thereof is cyclohexyl-[[5- (dicyclohexylphosphanylmethyl)acridin-4-yl]methyl]phosphane or diisopropyl-[[5- (diisopropylphosphanylmethyl)acridin-4-yl]methyl]phosphane. The process of any one of embodiments 1 to 41 , wherein the base is selected from the group consisting of alkali hydroxides, alkali alkoxides, and a mixture thereof. The process of embodiment 42, wherein the alkali hydroxide is selected from the group consisting of NaOH, KOH, and a mixture thereof, preferably wherein the alkali hydroxide is KOH. The process of embodiment 42, wherein the alkali alkoxide is selected from the group consisting of sodium alkoxides, potassium alkoxides, and a mixture of two or more thereof, preferably from the group consisting of sodium ethoxide, potassium ethoxide, and a mixture thereof. The process of any one of embodiments 1 to 44, wherein at least one of the at least one alcohol Ra-CH2-CH2-OH and at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc-CH2-OH, is a bio-based alcohol, preferably obtainable or obtained from sugar-containing crops, more preferably from one or more of sugar cane and corn. The process of any one of embodiments 1 to 3 and 5 to 45, wherein the liquid mixture ME according to (ii) further comprises a solvent component which comprises one or more solvents. The process of embodiment 46, wherein the one or more solvents of the solvent component have a boiling point at 1 atm (101325 Pa) of 140 °C or more, preferably a boiling point of 160 °C or more, more preferably a boiling point of 180 °C or more, more preferably a boiling point of 190 °C or more. The process of embodiment 46 or 47, wherein at 25 °C, the solvent component has a solubility in water in the range of from 0 to 0.5 weight-%, preferably in the range of from 0 to 0.1 weight-%, more preferably a solubility in water at 25 °C of from 0 to 0.05 weight-%, more preferably a solubility in water at 25 °C of from 0 to 0.01 weight-%, based on 100 weight-% water. The process of any one of embodiments 46 to 48, wherein the distribution coefficient of the catalyst in a system of the solvent component and water is from 0 to 0.01 , preferably from 0 to 0.005, more preferably from 0 to 0.005, based on 1 kg catalyst. The process of any one of embodiments 46 to 49, wherein the solvent component comprises at least two solvents with a boiling point at 1 atm (101325 Pa) of 180 °C or more. The process of any one of embodiments 46 to 50, wherein the solvent does not form an azeotrope with water. The process of any one of embodiments 46 to 51 , wherein the solvent component comprises at least one solvent selected from the group consisting of biphenyl, diphenyl ether, 1-tert-butyl-3,5-dimethyl-benzene, xylene, mesitylene, toluene, ethylbenzene, cycloedodecane, cyclononane, cyclooctane, cycloheptane, decaline, n-butylbutyrate, n- hexylhexyrate, n-octyloctyrate, texanole, di-n-butylether, di-iso-butylether, di-sec- butylether, and a mixture of two or more thereof, preferably from the group of biphenyl, diphenyl ether, 1-tert-butyl-3,5-dimethyl-benzene, ethylbenzene, cycloedodecane, cyclononane, cyclooctane, cycloheptane, decaline, n-butylbutyrate, n-hexylhexyrate, n- octyloctyrate, texanole, di-n-butylether, di-iso-butylether, di-sec-butylether, and a mixture of two or more thereof, more preferably from the group consisting of biphenyl, diphenyl ether, and a mixture thereof, wherein more preferably, the solvent is a mixture of biphenyl and diphenyl ether. The process of any one of embodiments 46 to 51 , wherein the solvent does not include any one of benzene, toluene, xylene or mesitylene. The process of any one of embodiments 46 to 53, wherein the solvent component comprises a mixture of biphenyl and diphenyl ether at a molar ratio of biphenyl relative to diphenyl ether in the range of from 1 :2 to 1 :6, preferably in the range of from 1 :2.5 to 1 :4. The process of any one of embodiments 46 to 54, wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol Ra-CH2-CH2-OH, the at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc-CH2-OH, the base, the solvent component and the catalyst. The process of any one of embodiments 46 to 55, wherein the alcohol conversion conditions according to (iii) comprise an amount of the solvent in the reaction mixture MGin the range of from 5 to 50 weight-%, preferably in the range of from 5 to 30 weight-%, more preferably in the range of from 5 to 10 weight-%, based on the total weight of the reaction mixture MG. The process of any one of embodiments 46 to 56, wherein the mixture MCs obtained according to (iv) comprises the component C and further comprises the solvent component. The process of any one of embodiments 1 to 57, wherein the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol selected from the group consisting of Ra-CH2-CH2-OH, Rb-CH2-CH2-OH and Rc-CH2-OH, the process further comprising separating at least a part of said unreacted alcohol from the liquid reaction mixture MG.

[0132] 59. The process of embodiment 58, wherein separating at least a part of the unreacted alcohol from MG is carried out by one or more of distillation, extraction, flashing, and membrane separation.

[0133] 60. The process of embodiment 58 or 59, wherein at least a part of the at least one unreacted alcohol separated from MGis recycled to (II) or (iii).

[0134] 61 . The process of any one of embodiments 1 to 60, further comprising

[0135] (v) recycling at least a part of the mixture MCs obtained according to (iv) to (ii) or (iii).

[0136] 62. The process of embodiment 61 , wherein the at least part of the mixture MCs recycled in (v) comprises at least a part of the component C.

[0137] 63. The process of any one of embodiments 61 or 62, wherein the at least part of the mixture Mcs recycled in (v) comprises at least a part of the component C and at least a part of the solvent component.

[0138] 64. The process of any one of embodiments 1 to 60, further comprising

[0139] (v) recycling at least a part of the mixture Mcs obtained according to (iv) to (ii) or (iii) by separating the solvent component and recycling the separated solvent component as part of the liquid mixture MEor the reaction mixture MGto (ii) or (iii).

[0140] 65. The process of any one of embodiments 1 to 64, wherein the reaction space SRis comprised in a reactor vessel, wherein the reactor vessel is preferably a completemixing reactor vessel.

[0141] 66. The process of embodiment 65, wherein the reactor vessel is selected from the group consisting of a stirred tank reactor, a fixed bed reactor, a mobile bed reactor, and a fluidized bed reactor.

[0142] The present invention is further illustrated by the following examples, which are set forth to illustrate certain aspects of the present invention and are not to be construed as limiting thereof.

[0143] Examples

[0144] The determination of the distribution coefficient of the solvent component in water comprises the following steps: 1 . combining the two components, e.g. feed and solvent component, in a predefined solvent ratio;

[0145] 2. turbulent mixing of the combined components over a longer period of time (> 10 min) at a defined extraction temperature;

[0146] 3. allowing for phase separation;

[0147] 4. taking samples of each phase at the extraction temperature;

[0148] 5. centrifuging the samples and withdrawing clear samples at the extraction temperature;

[0149] 6. analyzing the samples; and

[0150] 7. comparing the results of extract- and raffinate - calculation of the partition equilibrium / partition coefficient at the selected temperature.

[0151] Example 1

[0152] 42.52 g ethanol, 7.74 g methanol, 4.52 KOH solution (50 weight% in water), 243.8 mg Cy-Acr- PNP and 82.6 mg Ru(acac)s were transferred to a screw-cap bottle and stirred overnight at room temperature under argon atmosphere. This solution was transferred to a 300 mL HC autoclave via syringe and the bottle rinsed with 19.96 g ethanol. Then, 7.99 g of a solvent (biphenyl and diphenyl ether at a molar ratio of 1 :3) were added and the autoclave heated to 7? = 150 °C, while stirring at 750 rpm. Samples were taken regularly, filtered using a 2 pm syringe filter, combined with the internal standard 1 ,4-dioxane (0.8 g sample, 0.2 g standard) and finally analyzed via GC.

[0153] The formed catalyst had the following structure:

[0154] The GC shows the formation of 1 -propanol, isobutanol, 2-methyl-butan-1-ol and 1 -pentanol. The area percentage for each of the formed alcohols was 1 .4 at.-%, 0.1 at.-%, 0.2 at.-% and < 0.1 at.-%, respectively.

[0155] Cited literature:

[0156] M. Guerbet, C. R. Hebd. Seances Acad. Sci. 1899, 128, p. 511-513

[0157] - WO 2013 / 156399 A1

[0158] - A.Kaithal et al., “Ruthenium(ll)-Catalyzed p-Methylation of Alcohols using Methanol as C1 Source”, CHEMCATCHEM, vol. 11 , no. 21 , 2019-05-16, pages 5287 to 5291

[0159] - US 2015 / 246863 A1 N. Biswas et al., “Acridine-Based SNS-Ruthenium Pincer Complex-Catalyzed Borrowing Hydrogen-Mediated C-C Alkylation Reaction: Application to the Guerbet Reaction”, SYNLETT, vol. 34, no. 06, 2022-07-08, pages 622 to 628

[0160] - Y.Xie et al., “Highly efficient Process for Production of Biofuel from Ethanol Catalyzed by Ruthenium Pincer Complexes”, Journal of the American Society, vol. 138, no. 29, 2016-07-18, pages 9077 to 9080

[0161] - WO 2012 / 119928 A1

[0162] - US 2010 / 298613 A1

Claims

Claims1 . An alcohol conversion process, comprising(i) providing a component C which is at least one of a catalyst, a precursor thereof, a reduced form of the catalyst and a reduced form of the precursor;(ii) preparing a liquid mixture ME comprising at least one alcohol Ra-CH2-CH2-OH, at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc- CH2-OH, a base, and the component C provided according to (i), Ra, Rband Rcbeing independently from each other selected from the group consisting of H and Ci-C4-alkyl; wherein Ra-CH2-CH2-OH, Rb-CH2-CH2-OH and Rc-CH2-OH are different from each other;(iii) subjecting the liquid mixture MEprepared according to (ii) to alcohol conversion conditions in a reaction space SGand obtaining in SGa reaction mixture MGcomprising at least one alcohol selected from the group consisting of Rb-CH2- CH2-(CHRa-CH2)x-OH, Ra-CH2-CH2-(CHRb-CH2)x-OH and Rc-CH2-(CHRa-CH2)x- OH, x being an integer in the range of from 1 to 4, wherein the alcohol conversion conditions comprise a temperature of the reaction mixture MGin the range of from 100 to 250 °C and a pressure in the reaction space SGin the range of from 1 x 105to 4 x 106Pa;(iv) separating at least one alcohol selected from the group consisting of Rb-CH2- CH2-(CHRa-CH2)x-OH, Ra-CH2-CH2-(CHRb-CH2)x-OH and Rc-CH2-(CHRa-CH2)x- OH from the reaction mixture MGobtained according to (iii), obtaining a mixture Mcs! wherein(a) the base is selected from the group consisting of ammonium hydroxide, alkali hydroxides, alkaline earth hydroxides, ammonium carbonate, ammonium hydrogen carbonate, alkali carbonates, alkali hydrogen carbonates, alkaline earth carbonates, alkaline hydrogen carbonates, alkali alkoxides, alkaline earth alkoxides, alkali amides, alkaline earth amides, alkali metal 2, 2,6,6- tetramethylpiperidines, alkaline earth metal 2,2,6,6-tetramethylpiperidines, secondary amino acids, and a mixture of two or more thereof;(b) the catalyst comprises a compound of formula (A)whereinM is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, S(=O)Rs, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRdRe, SbRdRe, and a N-heterocyclic carbene represented by the structures:L3is selected from the group consisting of CO, PRdReRf, AsRdReRf, SbRdReRf, SRdRe, RsCN, RsNC, N2, PF3, pyridine, and thiophene;R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the compound of formula (A) a quinolinyl unit; n is 0 or 1 ;Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, OH, OR, NRS2, NH3, NRg3, and R92NSO2R9;Rd, Re, Rf, Rg, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted C1-C1 o-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3-Cio-cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C3-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted C5-Cio-aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and unsubstituted or substituted C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2and Ci-Cio-alkyl; andX is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; and(c) the precursor of the catalyst comprising a compound of formula (A) comprises a mixture comprising 1 ) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, organic carbonyl compounds, Ci-Cio-alkyl, C3-Ci2-cycloalkyl, C2- Ci2-alkenyl, Cs-Cis-cycloalkenyl, Cs-C2o-aryl, CN, CO, OH, OC(=O)CF3,OSO2CF3, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H)M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;L1and L2, are, independently of each other, PRdRe, NRdRe, SRd, SH, S(=O)Rg, Cs-Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRdRe, SbRdRe, and a N-heterocyclic carbene represented by the structures:R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst of formula (A) an acridinyl unit, or R1and R2or R3and R4form together with the pyridyl unit of the catalyst of formula (A) a quinolinyl unit; n is 0 or 1 ;Rd, Re, Rf, Rg, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted C1-C1 o-alkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C-io-alkyl; unsubstituted or substituted C3-Cio-cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C-io-alkyl; unsubstituted or substituted Cs-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C-io-alkyl; unsubstituted or substituted C5-Cio-aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C-io-alkyl; and unsubstituted or substituted Cs-Cw-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2 and Ci-C-io-alkyl; andX is optional and is selected from the group consisting of one, two, three, four, five, six, and seven substituents positioned at any carbon atom on the acridinyl unit, or one, two, three, four and five substituents positioned at any carbon atom on the quinolinyl unit, or one substituent positioned at the carbon atom on the pyridyl unit, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl.2.. The process of claim 1 , wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-%, more preferably from 98 to 100 weight-%, more preferably from 99 to 100 weight-% of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol Ra-CH2-CH2-OH, at least one alcohol selected from the group consisting of Rb- CH2-CH2-OH and Rc-CH2-OH, the base, and the component C.

3. The process of claim 1 or 2, wherein the reaction space SGaccording to (iii) comprises the reaction mixture MG and a gas phase, wherein the gas phase comprises H2, and wherein the alcohol conversion conditions according to (iii) comprise maintaining the H2partial pressure of the gas phase in the range of from 2 x 104to 3.1 x 106Pa, preferably in the range of from 2 x 104to 1 .1 x 106Pa, more preferably in the range of from 2 x 104to 6 x 105Pa.

4. The process of claim 3, wherein the H2partial pressure of the gas phase is maintained by introducing H2into the gas phase; or wherein the H2partial pressure of the gas phase is maintained by relaxation of the gas phase, preferably by removing at least a part of H2from the gas phase.

5. The process of any one of claims 1 to 4, wherein the component C comprises a mixture, wherein said mixture comprises: 1) a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, organic carbonyl compounds, Ci-Ci0-alkyl, C3-Ci2-cycloalkyl, C2- Ci2-alkenyl, Cs-Cis-cycloalkenyl, C5-C2o-aryl, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H’)wherein M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;L1and L2are, independently of each other, PRdRe, NRdRe, SRd, SH, and S(=O)Rs;L3is selected from the group consisting of CO, PRdReRf, SRdRe, RdCN, RdNC, N2, PF3, pyridine, and thiophene;R1, R2, R3and R4either are hydrogen, or form together with the pyridyl unit of the catalyst comprising a compound of formula (A) an acridinyl unit; n is 0 or 1 , and if R1, R2, R3and R4are hydrogen, n is 0;Rd, Re, Rfand Rs, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cio-alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; unsubstituted or substituted Cs-Cio-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cio-alkyl; Cs-Cio-heterocycle comprisingat least one heteroatom selected from the group consisting of N, O, and S; Cs-C-io-aryl; and C5-Cio-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; andY is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

6. The process of any one of claims 1 to 5, wherein the component C comprises a compound of formula (D)wherein Cy is cyclohexyl; or wherein the component C comprises a compound of formula (E)wherein the component C comprises a compound of formula (F)wherein tBu is tert-butyl.

7. The process of any one of claims 1 to 6, wherein Rais H or methyl.

8. The process of any one of claims 1 to 7, wherein Rband Rcare independently from each other selected from the group consisting of H and methyl.

9. The process of any one of claims 1 to 8, wherein the liquid mixture ME prepared according to (ii) further comprises a compound of formula (G) or a reduced form thereofwherein R1, R2, R3and R4, L1, L2, and n as defined above.

10. The process of claim 9, wherein in the liquid mixture ME prepared according to (ii) and subjected to alcohol conversion conditions according to (iii), the molar ratio of the compound of formula (G) or a reduced form thereof relative to the component C is in the range of from 1 : 1 to 10: 1 .11 . The process of any one of claims 1 and 3 to 10, wherein the liquid mixture ME according to (ii) further comprises a solvent component which comprises one or more solvents.

12. The process of claim 11 , wherein the one or more solvents of the solvent component have a boiling point at 1 atm (101325 Pa) of 140 °C or more.

13. The process of claim 11 or 12, wherein the solvent component comprises at least two solvents with a boiling point at 1 atm (101325 Pa) of 180 °C or more.

14. The process of any one of claims 11 to 13, wherein from 90 to 100 weight-%, preferably from 95 to 100 weight-% of the liquid mixture MEprepared according to (ii) consist of the at least one alcohol Ra-CH2-CH2-OH, the at least one alcohol selected from the group consisting of Rb-CH2-CH2-OH and Rc-CH2-OH, the base, the solvent component and the catalyst.

15. The process of any one of claims 1 to 14, wherein the liquid reaction mixture MGobtained according to (iii) further comprises at least one unreacted alcohol selected from the group consisting of Ra-CH2-CH2-OH, Rb-CH2-CH2-OH and Rc-CH2-OH, the process further comprising separating at least a part of said unreacted alcohol from the liquid reaction mixture MG, wherein preferably at least a part of the at least one unreacted alcohol separated from MGis recycled to (ii) or (iii).

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