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, an alcohol can be converted in the presence of water with increased productivities. Since water does not have to be removed, the process is less energy intensive, saving costs and allowing for an overall more positive carbon dioxide footprint as compared to processes known up to date.

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. 511- 513). 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 a,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] WO 2015 / 031561 A1 relates to a method of converting a lower alcohol such as ethanol to a higher alcohol, e.g., butanol, in the presence of a water stable transition metal catalyst comprising a Group VIII transition metal and a polydentate nitrogen donor ligand. 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.

[0008] 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.

[0009] N. Biswas at 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 p-alkylated dimeric alcohols.

[0010] Up to date, the presence of water in the Guerbet reaction is considered as disadvantageous. Thus, water formed due to the condensation reaction must be removed from the reaction mixture, which is a burden on the costs of the system employed and energy intensive. Also, any starting materials for the reaction should preferably not contain water at all. Any alcohols used as a starting material, such as ethanol, which may be obtained as a mixture of alcohol and water, for example an azeotropic mixture thereof, must therefore be purified prior to the alcohol conversion process, which is also very energy demanding.

[0011] Therefore, it was an object of the present invention to provide an alcohol conversion process allowing a profitable and sustainable approach to produce alcohols allowing for the presence of water to avoid the afore-mentioned disadvantages of prior art processes up to date and to allow for increased productivities.

[0012] 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 together with water, allowing a profitable and sustainable approach to produce alcohols with increased productivities. The possibility to allow the presence of water during the reaction circumvents cost and energy intensive purification of the starting materials and any water removal steps during the reaction can effectively be omitted, also contributing to overall energy savings. In addition, advantageously, any unreacted alcohol as a result of the reaction can be recycled as a mixture with water, further contributing to energy savings as an energy intensive and costly separation of water and alcohol can be omitted. The process in accordance with the present invention thus overall has a more positive carbon dioxide footprint as compared to processes known up to date. The present invention in particular relates to an alcohol conversion process, comprising

[0013] (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;

[0014] (II) preparing a liquid mixture ME comprising at least one R-CH2-CH2-OH, a base, water, and the component C provided according to (I), R being selected from the group consisting of H and Ci-C4-alkyl;

[0015] (iii) subjecting the liquid mixture ME prepared 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 R-CH2-CH2-(CHR-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 MG in 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; wherein the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol R-CH2-CH2-OH;

[0016] (iv) separating at least a part of said at least one unreacted alcohol R-CH2-CH2-OH from the liquid reaction mixture MG;

[0017] (v) separating the at least one alcohol R-CH2-CH2-(CHR-CH2)X-OH from the reaction mixture MG obtained according to (iii), obtaining the at least one alcohol R-CH2- CH2-(CHR-CH2)X-OH and a mixture Mos;

[0018] (vi) recycling at least a part of the at least one unreacted alcohol R-CH2-CH2-OH obtained according to (iv) to (ii) or (iii); wherein

[0019] (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;

[0020] (b) the liquid mixture ME according to (ii) comprises an amount of the water in the liquid mixture ME in the range of from 0.5 to 25 weight-%, based on the total weight of the liquid mixture ME;

[0021] (c) the alcohol conversion conditions according to (iii) comprise an amount of the water in the reaction mixture MG in the range of from 0.5 to 25 weight-%, based on the total weight of the reaction mixture MG;

[0022] (d) 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, PRaRb, NRaRb, SRa, SH, S(=O)Rd, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N -heterocyclic carbene represented by the structures:

[0026] L3is selected from the group consisting of CO, PRaRbRc, AsRaRbRc, SbRaRbRc, SRaRb, RdCN, RdNC, 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 catalyst 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, NRd2, NH3, NRd3, and Rd2NSO2Rd;

[0029] Ra, Rb, Rc, Rd, R5, R6and R7are, 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 Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted Cs-C -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 -alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; and unsubstituted or substituted Cs-C -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 -alkyl; and 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-C -alkyl; and

[0030] (e) the precursor of the catalyst comprising a compound of formula (A) comprises 1) a mixture comprising a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-C -alkyl, C3-Ci2-cycloalkyl, C2- Ci2-alkenyl, Cs-C-is-cycloalkenyl, Cs-C2o-aryl, CN, CO, OH, OC(=O)CF3, OSO2CF3, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H)

[0031] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0032] L1and L2, are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, Cs-Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N-heterocyclic carbene represented by the structures:

[0033] 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 ;

[0034] Ra, Rb, Rc, Rd, R5, R6and R7are, 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 Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted Cs-C -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 -alkyl; unsubstituted or substituted Cs-C -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-C -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

[0035] 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.

[0036] Figure 1 illustrates the influence of the presence of water on the ethanol conversion rate when employing a solvent.

[0037] Figure 2 illustrates the influence of the presence of water on the butanol selectivity when employing a solvent.

[0038] Figure 3 illustrates the influence of the presence of water on the ethanol conversion rate without the presence of solvent.

[0039] Figure 4 illustrates the influence of the presence of water on the butanol selectivity without the presence of solvent.

[0040] Figure 5 illustrates the influence of the presence of water on the ethanol conversion rate.

[0041] Figure 6 illustrates the influence of the presence of water on the butanol selectivity.

[0042] 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.

[0043] 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 ME prepared according to (ii) consist of the at least one alcohol R-CH2-CH2-OH, the base, water and the component C.

[0044] 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.

[0045] In the process in accordance with the present invention, the alcohol conversion conditions according to (iii) preferably comprise a pressure in the reaction space SG in 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.

[0046] In the process in accordance with the present invention, 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.

[0047] 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.

[0048] Preferably, the alcohol conversion conditions according to (iii) comprise an amount of the 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.

[0049] It is preferred that the liquid mixture ME according to (ii) comprises an amount of the water in the liquid mixture ME in the range of from 1 to 25 weight-%, more preferably in the range of from 2 to 20 weight-%, more preferably in the range of from 4 to 18 weight-%, more preferably in the range of from 5 to 15 weight-%, more preferably in the range of from 8 to 13 weight-%, based on the total weight of the liquid mixture ME.

[0050] The alcohol conversion conditions according to (iii) preferably comprise an amount of water in the reaction mixture MG in the range of from 0.8 to 25 weight-%, more preferably in the range of from 1.0 to 20 weight-%, more preferably in the range of from 3 to 18 weight-%, more preferably in the range of from 4 to 15 weight-%, more preferably in the range of from 5 to 13 weight-%, more preferably in the range of from 5 to 10 weight-%, based on the total weight of the reaction mixture MG.

[0051] In another preferred embodiment, the reaction space SG according 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 H2 partial 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.

[0052] The H2 partial pressure of the gas phase is preferably maintained by introducing H2 into the gas phase. Also, the H2 partial pressure of the gas phase is preferably maintained by relaxation of the gas phase, more preferably by removing at least a part of H2 from the gas phase. “Maintaining” the H2 partial pressure of the gas phase in the sense of the present invention includes ensuring that the H2 partial pressure is within the desired range during the reaction. In case the H2 partial 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 H2 partial pressure is neither too high nor too low, the H2 partial pressure may preferably be adjusted, or must be adjusted in case of ensuring that the H2 partial pressure is maintained within the desired range, for example by relaxation of the gas phase, in which case the H2 partial pressure may be reduced, or, alternatively, by introducing H2 into the gas phase, in which case the H2 partial pressure may be increased. Depending upon the H2 partial pressure during the reaction, one or even both of said alternatives may be carried out if desired to adjust the H2 partial pressure and to maintain the H2 partial pressure within the desired pressure range at all times during the reaction.

[0053] 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 H2 partial 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 H2 partial 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 H2 partial pressure increasing. By relaxation of the gas phase, hydrogen can be removed from the gas phase and the H2 partial pressure can be maintained in the desired range. Thus, in one preferred embodiment, the H2 partial 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 H2 partial pressure may be reduced, or, alternatively, by introducing H2 into the gas phase, in which case the H2 partial pressure may be increased.

[0054] 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.

[0055] 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, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, C1- Cw-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, PRaRb, NRaRb, SRa, SH, and S(=O)Rd; L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0056] 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;

[0057] Ra, Rb, Rcand Rd, 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-C10-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 -alkyl; Cs-C -heterocycle comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -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.

[0058] Preferably, the component C comprises a compound comprising a metal M selected from the group consisting of IrCh x H2O, [lr(COD)CI]2, [I r(COE)2CI]2, [I r(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)Cl2]2, [Ru(benzene)Cl2]y, [Ru(CO)2Cl2]y, where y is in each case in the range from 1 to 1000, [RU(CO)3CI2]2, [Ru(CO D)(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)Cl2]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.

[0059] Preferably, the component C comprises a compound of formula (A’)

[0060]

[0061] In a preferred embodiment, the component C comprises a compound of formula (B) wherein

[0062] M is selected from the group consisting of Ir, Ru, and Mn;

[0063] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0064] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0065] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-C10-alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C10-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; Cs-Cio-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -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.

[0066] Also preferred is that the component C comprises a compound of formula (C) wherein

[0067] M is selected from the group consisting of Ir, Ru, and Mn;

[0068] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0069] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0070] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cw-alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cw-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; Cs-Cw-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-Cw-aryl; and Cs-Cw-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0071] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, and OH.

[0072] M is preferably selected from the group consisting of Ir and Ru, and more preferably M is Ru.

[0073] L3is preferably CO.

[0074] Preferably, L1and L2are each (PRdRe), and wherein Rdand Reare Ci-Cw-alkyl, more preferably wherein Rdand Reare each isopropyl or tert-butyl. Alternatively, L1and L2are preferably each (PRdRe), and wherein Rdand Reare Cs-Cw-cycloalkyl, more preferably wherein Rdand Reare each cyclohexyl. Alternatively, L1and L2are each (PRdRe), and wherein Rdand Reare Cs-C -aryl.

[0075] Y preferably is 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.

[0076] In another preferred embodiment, the component C comprises a compound of formula (D) wherein Cy is cyclohexyl.

[0077] Also preferred is that the component C comprises a reduced form of the catalyst of formula (D’) wherein Cy is cyclohexyl.

[0078] It is furthermore preferred that the component C comprises a compound of formula (E) wherein iPr is isopropyl.

[0079] Also preferred is that component C comprises a reduced form of the catalyst of formula (E’) wherein iPr is isopropyl.

[0080] It is moreover preferred that the component C comprises a compound of formula (F) wherein tBu is tert-butyl.

[0081] Preferably, the component C comprises a reduced form of the catalyst of formula (F’) wherein tBu is tert-butyl.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] Integer x is preferably 1 or 2, more preferably integer x is 1 .

[0086] Preferably, R is 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, more preferably wherein R is H.

[0087] In a preferred embodiment, 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. 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 0 is 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.

[0088] 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) is cyclohexyl- [[5-(dicyclohexylphosphanylmethyl)acridin-4-yl]methyl]phosphane or diisopropyl-[[5- (diisopropylphosphanylmethyl)acridin-4-yl]methyl]phosphane. 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.

[0089] The at least one alcohol R-CH2-CH2-OH preferably is a bio-based alcohol, preferably obtainable or obtained from sugar-containing crops, more preferably from one or more of sugar cane and corn.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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 consisting of biphenyl, diphenyl ether, and a mixture thereof, wherein more preferably, the solvent is a mixture of biphenyl and diphenyl ether.

[0094] 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.

[0095] In a preferred embodiment, the solvent does not include any one of benzene, toluene, xylene or mesitylene.

[0096] 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.

[0097] 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, more preferably in the range of from 1 :2.5 to 1 :4.

[0098] 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 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.

[0099] The alcohol conversion conditions according to (iii) preferably comprise an amount of the solvent in the reaction mixture MG in 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.

[0100] The mixture Mos obtained according to (iv) preferably comprises the component C and further comprises the solvent component.

[0101] Preferably, the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol R-CH2-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 MG is recycled to (ii) or (iii).

[0102] In the process in accordance with the present invention, (iv) separating at least a part of said unreacted alcohol R-CH2-CH2-OH from the liquid reaction mixture MG preferably comprises separation of the unreacted alcohol R-CH2-CH2-OH in form of a mixture of said alcohol with water, wherein the amount of water is up to 15 weight-%, more preferably up to 12 weight-%, more preferably from 2 to 12 weight-%, more preferably from 3 to 10 weight-%, more preferably from 4 to 9 weight-%, more preferably from 6 to 8 weight-%.

[0103] In a more preferred embodiment, (vi) recycling at least a part of the at least one unreacted alcohol R-CH2-CH2-OH separated from the reaction mixture MG to (II) or (Hi) comprises recycling the mixture of the unreacted alcohol R-CH2-CH2-OH and water. Even more preferred is that (vi) the mixture recycled comprises at least a part of the at least one unreacted alcohol R-CH2-CH2-OH and water, wherein the amount of water is up to 15 weight- %, more preferably up to 12 weight-%, more preferably from 2 to 12 weight-%, more preferably from 3 to 10 weight-%, more preferably from 4 to 9 weight-%, more preferably from 6 to 8 weight-%.

[0104] The process in accordance with the present invention preferably further comprises (v) recycling at least a part of the mixture Mos obtained according to (iv) to (ii) or (iii). More preferred is that the at least part of the mixture Mos recycled in (v) comprises at least a part of the component C. Also more preferred is that the at least part of the mixture Mos recycled in (v) comprises at least a part of the component C and at least a part of the solvent component.

[0105] The process in accordance with the present invention preferably further comprises

[0106] (v) recycling at least a part of the mixture Mos 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 ME or the reaction mixture MG to (ii) or (iii).

[0107] In a preferred embodiment, the reaction space SR is 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.

[0108] 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.

[0109] 1 . An alcohol conversion process, comprising

[0110] (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 R-CH2-CH2-OH, a base, water, and the component C provided according to (I), R being selected from the group consisting of H and Ci-C4-alkyl;

[0111] (iii) subjecting the liquid mixture ME prepared 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 R-CH2-CH2-(CHR-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 MG in 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; wherein the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol R-CH2-CH2-OH;

[0112] (iv) separating at least a part of said at least one unreacted alcohol R-CH2-CH2-OH from the liquid reaction mixture MG;

[0113] (v) separating the at least one alcohol R-CH2-CH2-(CHR-CH2)X-OH from the reaction mixture MG obtained according to (iii), obtaining the at least one alcohol R-CH2- CH2-(CHR-CH2)X-OH and a mixture Mos;

[0114] (vi) recycling at least a part of the at least one unreacted alcohol R-CH2-CH2-OH obtained according to (iv) to (ii) or (iii); wherein

[0115] (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;

[0116] (b) the liquid mixture ME according to (ii) comprises an amount of the water in the liquid mixture ME in the range of from 0.5 to 25 weight-%, based on the total weight of the liquid mixture ME;

[0117] (c) the alcohol conversion conditions according to (iii) comprise an amount of the water in the reaction mixture MG in the range of from 0.5 to 25 weight-%, based on the total weight of the reaction mixture MG;

[0118] (d) the catalyst comprises a compound of formula (A) (A), wherein

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

[0120] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N -heterocyclic carbene represented by the structures:

[0121] L3is selected from the group consisting of CO, PRaRbRc, AsRaRbRc, SbRaRbRc, SRaRb, RdCN, RdNC, N2, PF3, pyridine, and thiophene;

[0122] 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 ;

[0123] Y is selected from the group consisting of H, F, Cl, Br, I, OC(=O)CF3, OSO2CF3, CN, CO, OH, OR, NRd2, NH3, NRd3, and Rd2NSO2Rd;

[0124] Ra, Rb, Rc, Rd, R5, R6and R7are, 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 Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted Cs-C -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 -alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; and unsubstituted or substituted Cs-C -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 -alkyl; and

[0125] 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-C -alkyl; and

[0126] (e) the precursor of the catalyst comprising a compound of formula (A) comprises 1) a mixture comprising a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-Cw-alkyl, Cs-Cw-cycloalkyl, C2- Ci2-alkenyl, Cs-Cw-cycloalkenyl, Cs-C2o-aryl, CN, CO, OH, OC(=O)CF3, OSO2CF3, hydrides, pyridines, halogenides, hydroxides, and thiophenes; and 3) a compound of formula (H)

[0127] M is selected from the group consisting of Ir, Mn, Os, Pd, Pt, Rh, and Ru;

[0128] L1and L2, are, independently of each other, PRaRb, NRaRb, SRa, SH, S(=O)Rd, Cs-Cw-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N-heterocyclic carbene represented by the structures:

[0129] 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 ;

[0130] Ra, Rb, Rc, Rd, R5, R6and R7are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cw-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-Cw-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-Cw-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-Cw-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, NH2 and Ci-Cw-alkyl; and

[0131] 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. The process 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 R-CH2-CH2-OH, the base, water and the component C. The process of any one of embodiments 1 to 4, wherein 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 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 (iii) comprise a pressure in the reaction space SG in the range of from 1 x 105to 3.5 x 106Pa, 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. 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 MG in 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 MG in 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 the component C in the reaction mixture MG in 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 liquid mixture ME according to (ii) comprises an amount of the water in the liquid mixture ME in the range of from 1 to 25 weight-%, preferably in the range of from 2 to 20 weight-%, more preferably in the range of from 4 to 18 weight-%, more preferably in the range of from 5 to 15 weight-%, more preferably in the range of from 8 to 15 weight-%, based on the total weight of the liquid mixture ME. The process of any one of embodiments 1 to 10, wherein the alcohol conversion conditions according to (iii) comprise an amount of water in the reaction mixture MG in the range of from 0.8 to 25 weight-%, preferably in the range of from 1 .0 to 20 weight- %, more preferably in the range of from 3 to 18 weight-%, more preferably in the range of from 4 to 15 weight-%, more preferably in the range of from 5 to 13 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 1 to 11 , wherein the reaction space SG according 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 H2 partial 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 12, wherein the H2 partial pressure of the gas phase is maintained by introducing H2 into the gas phase. The process of embodiment 12 or 13, wherein the H2 partial pressure of the gas phase is maintained by relaxation of the gas phase. The process of any one of embodiments 12 to 14, wherein the H2 partial 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 H2 into the gas phase. The process of any one of embodiments 12 to 14, wherein the H2 partial 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 H2 into the gas phase. The process of any one of embodiments 1 to 16, 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, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-C-io-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;

[0132] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0133] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0134] 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;

[0135] Ra, Rb, Rcand Rd, 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 Cs-C -cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; Cs-C -heterocycle comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0136] 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 16, wherein the component C comprises a compound comprising a metal M selected from the group consisting of I rCh x H2O, [lr(COD)CI]2, [lr(COE)2CI]2, [lr(C2H4)2CI]2, [lr(COD)OH]2, [lr(COD)MeO]2, [lrCp*CI2], [IrCp CI2], 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 16, wherein the component C comprises a compound comprising a metal M selected from the group consisting of [Ru(p- cymene)Cl2]2, [Ru(benzene)Cl2]y, [Ru(CO)2Cl2]y, where y is in each case in the range from 1 to 1000, [Ru(CO)3Cl2]2, [Ru(COD)(allyl)], RuCh x H2O, [Ru(acetylacetonate)3], [Ru(DMSO)4Cl2], [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 16, wherein the component C comprises a compound of formula (B) wherein

[0137] M is selected from the group consisting of Ir, Ru, and Mn;

[0138] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd;

[0139] L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0140] Ra, Rb, Rcand Rd, 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 Cs-C -cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; Cs-C -heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0141] 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 16, wherein the component C comprises a compound of formula (C) wherein

[0142] M is selected from the group consisting of Ir, Ru, and Mn;

[0143] L1and L2are, independently of each other, PRaRb, NRaRb, SRa, SH, and S(=O)Rd; L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, pyridine, and thiophene;

[0144] Ra, Rb, Rcand Rd, are, independently of each other, selected from the group consisting of H, unsubstituted or substituted Ci-Cw-alkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cw-alkyl; unsubstituted or substituted Cs-Cw-cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-Cw-alkyl; Cs-Cw-heterocyclyl comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-Cw-aryl; and Cs-Cw-heteroaryl comprising at least one heteroatom selected from the group consisting of N, O, and S; and

[0145] 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 16, 20 and 21 , wherein M is selected from the group consisting of Ir and Ru, wherein M is preferably Ru. The process of any one of embodiments 1 to 16, and 20 to 22, wherein L3is CO. The process of any one of embodiments 1 to 16, and 20 to 22, wherein L1and L2are each (PRaRb), and wherein Raand Rbare Ci-Cw-alkyl, preferably wherein Rdand Reare each isopropyl or tert-butyl. The process of any one of embodiments 1 to 16, and 20 to 22, wherein L1and L2are each (PRaRb), and wherein Raand Rbare Cs-Cw-cycloalkyl, preferably wherein Raand Rbare each cyclohexyl. The process of any one of embodiments 1 to 16, and 20 to 22, wherein L1and L2are each (PRaRb), and wherein Raand Rbare Cs-C -aryl. The process of any one of embodiments 1 to 16, and 20 to 26, 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 16, and 20 to 26, wherein Y is CO. The process of any one of embodiments 1 to 16, wherein the component C comprises a compound of formula (D) wherein Cy is cyclohexyl. The process of any one of embodiments 1 to 16 and 29, 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 16, wherein the component C comprises a compound of formula (E) wherein iPr is isopropyl. The process of any one of embodiments 1 to 16 and 31 , 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 16, wherein the component C comprises a compound of formula (F) wherein tBu is tert-butyl. The process of any one of embodiments 1 to 16 and 33, 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 34, 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 34, 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 34, wherein the reduced form of the precursor comprises a compound of formula (P-l I): -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 37, wherein integer x is 1 or 2, preferably wherein integer x is 1 . The process of any one of embodiments 1 to 38, wherein R is 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, more preferably wherein R is H. The process of any one of embodiments 1 to 39, 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 40, 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 40 or 41 , 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 , 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 40 to 42, wherein the compound of formula

[0146] (G) 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) 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 43, wherein the base is selected from the group consisting of alkali hydroxides, alkali alkoxides, and a mixture of two or more thereof. The process of embodiment 44, 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 44, 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 46, wherein the at least one alcohol R- CH2-CH2-OH is a bio-based alcohol, preferably obtainable or obtained from sugar- containing crops, preferably from one or more of sugar cane and corn. The process of any one of embodiments 1 to 3 and 5 to 47, wherein the liquid mixture ME according to (ii) further comprises a solvent component which comprises one or more solvents. The process of embodiment 48, 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 48 or 49, 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 48 to 50, 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 48 to 51 , 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 48 to 52, wherein the solvent does not form an azeotrope with water. The process of any one of embodiments 48 to 53, 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 -octyl octy rate, 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. The process of any one of embodiments 48 to 53, wherein the solvent does not include any one of benzene, toluene, xylene or mesitylene. The process of any one of embodiments 48 to 55, 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 48 to 56, 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 R-CH2-CH2-OH, the base, water, the solvent and the catalyst. The process of any one of embodiments 48 to 57, wherein the alcohol conversion conditions according to (iii) comprise an amount of the solvent in the reaction mixture MG in 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 48 to 58, wherein the mixture Mos obtained according to (iv) comprises the component C and further comprises the solvent component. The process of any one of embodiments 1 to 59, wherein the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol R-CH2-CH2- OH, the process further comprising separating at least a part of said unreacted alcohol from the liquid reaction mixture MG. The process of embodiment 60, 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. The process of embodiment 60 or 61 , wherein at least a part of the at least one unreacted alcohol separated from MG is recycled to (ii) or (iii). The process of any one of embodiments 60 to 62, wherein (iv) separating at least a part of said unreacted alcohol R-CH2-CH2-OH from the liquid reaction mixture MG comprises separation of the unreacted alcohol R-CH2-CH2-OH in form of a mixture of said alcohol with water, wherein the amount of water is up to 15 weight-%, preferably up to 12 weight-%, more preferably from 2 to 12 weight-%, more preferably from 3 to 10 weight-%, more preferably from 4 to 9 weight-%, more preferably from 6 to 8 weight- The process of embodiment 62 or 63, wherein (vi) recycling at least a part of the at least one unreacted alcohol R-CH2-CH2-OH separated from the reaction mixture MG to (ii) or (iii) comprises recycling the mixture of the unreacted alcohol R-CH2-CH2-OH and water. The process of embodiment 64, wherein (vi) the mixture recycled comprises at least a part of the at least one unreacted alcohol R-CH2-CH2-OH and water, wherein the amount of water is up to 15 weight-%, preferably up to 12 weight-%, preferably from 2 to 12 weight-%, more preferably from 3 to 10 weight-%, more preferably from 4 to 9 weight-%, more preferably from 6 to 8 weight-%. The process of any one of embodiments 1 to 65, further comprising

[0147] (v) recycling at least a part of the mixture Mos obtained according to (iv) to (ii) or (iii). The process of embodiment 66, wherein the at least part of the mixture Mos recycled in (v) comprises at least a part of the component C. 68. The process of any one of embodiments 66 or 67, 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.

[0148] 69. The process of any one of embodiments 48 to 68, further comprising

[0149] (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 ME or the reaction mixture MG to (ii) or (iii).

[0150] 70. The process of any one of embodiments 1 to 69, wherein the reaction space SR is comprised in a reactor vessel, wherein the reactor vessel is preferably a completemixing reactor vessel.

[0151] 71 . The process of embodiment 70, 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.

[0152] 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.

[0153] Examples

[0154] The determination of the distribution coefficient of the solvent component in water comprises the following steps:

[0155] 1. combining the two components, e.g. feed and solvent component, in a predefined solvent ratio;

[0156] 2. turbulent mixing of the combined components over a longer period of time (> 10 min) at a defined extraction temperature;

[0157] 3. allowing for phase separation;

[0158] 4. taking samples of each phase at the extraction temperature;

[0159] 5. centrifuging the samples and withdrawing clear samples at the extraction temperature;

[0160] 6. analyzing the samples; and

[0161] 7. comparing the results of extract- and raffinate - calculation of the partition equilibrium / partition coefficient at the selected temperature.

[0162] Example 1

[0163] 50.31 g Ethanol, 3.82 g potassium ethoxide, 90.30 mg Ru(acac)s and Cy-Acr-PNP (273.10 mg) were weighed into a screw thread bottle and stirred overnight at room temperature. The reactant suspension was poured into an autoclave using a syringe in a countercurrent flow of the starting material, and the screw-threaded bottle was rinsed with 20 g ethanol. Then, 7.76 g diphenyl and diphenyl ether were added as solvent in a molar ratio of 1 :3. The reaction mixture was heated to 150 °C with 750 rpm stirring. The pressure was maintained at about 10 bar during the reaction. After reaching the reaction temperature of 150 °C, a "zero sample" was taken, filtered through a 2 pm syringe filter, the sample was spiked with the internal standard 1 ,4-dioxane and analyzed by GC. Further samples were taken after 1 , 2, 3, 6 and 24 h and processed / analyzed analogously.

[0164] The formed catalyst had the following structure:

[0165] Example 2

[0166] Example 2 was carried out as example 1 , with the following mass:

[0167] 90.90 mg Ru(acac)s, 274.00 mg Cy-Acr-PNP, 70.51 g ethanol, 3.84 g potassium ethoxide, 7.80 g diphenyl and diphenyl ether in a molar ratio of 1 :3, 4.2 g water.

[0168] Example 3

[0169] Example 3 was carried out as example 1 , with the following mass:

[0170] 90.50 mg Ru(acac)s, 271.60 mg Cy-Acr-PNP, 70.32 g ethanol, 3.81 g potassium ethoxide, 7.75 g diphenyl and diphenyl ether in a molar ratio of 1 :3, 8.4 g water.

[0171] Example 4

[0172] Example 4 was carried out as example 1 , with the following mass:

[0173] 95.40 mg Ru(acac)s, 286.30 mg Cy-Acr-PNP, 73.89 g ethanol, 4.02 g potassium ethoxide, 3.86 g water.

[0174] Example 5

[0175] Example 5 was carried out as example 1 , with the following mass:

[0176] 90.30 mg Ru(acac)s, 270.80 mg Cy-Acr-PNP, 70.10 g ethanol, 3.80 g potassium ethoxide, 7.76 g water.

[0177] Example 6 Example 6 was carried out as example 1 , with the following mass:

[0178] 98.9 mg Ru(acac)3, 297.70 mg Cy-Acr-PNP, 77.35 g ethanol, 4.18 g potassium ethoxide.

[0179] Example 7

[0180] Example 7 was carried out as example 1 , with the following mass:

[0181] 77.50 mg Ru(acac)s, 164.60 mg IPr-Acr-PNP, 64.71 g ethanol, 3.15 g potassium ethoxide.

[0182] Example 8

[0183] Example 8 was carried out as example 1 , with the following mass:

[0184] 88.10 mg Ru(acac)s, 194.40 mg IPr-Acr-PNP, 70.00 g ethanol, 3.72 g potassium ethoxide, 3.99 g water.

[0185] Example 9

[0186] Example 9 was carried out as example 1 , with the following mass:

[0187] 76.70 mg Ru(acac)s, 169.20 mg IPr-Acr-PNP, 62.90 g ethanol, 3.24 g potassium ethoxide, 6.59 g water.

[0188] Figure 1 is a conversion-time diagram for different water quantities using the above component C system. Figure 2 is a selectivity-conversion diagram for different water quantities using the the above component C system. The reaction conditions were: 72 g EtOH, 8 g diphenyl and diphenyl ether in a molar ratio of 1 :3, 0.015 mol% Ru(acac)s, 0.03 mol% Cy-Acr-PNP, 3 mol% KOEt, indicated amount of water, 10 bar, 150 °C.

[0189] As may be seen from the conversion-time diagram shown in Figure 1 , addition of water effected the reactivity more than just diluting the system. The rate of reaction drops with increasing water content; however, this effect is only small when 5 weight- % of water was added to the reaction mixture (e.g., after 3 h 38 vs. 35% conversion). At 10 weight- % water, the reactivity dropped more substantially and only 30% conversion were obtained after 30 h.

[0190] Apart from reducing the rate of the reaction, the water also effected the selectivity of the process. As shown in Figure 2, the butanol selectivity increases at the same conversion with increasing water content by avoiding formation of higher alcohols.

[0191] This set of examples was repeated without solvent (no diphenyl and diphenyl ether present), the results shown in Figures 3 and 4. The experimental setup was slightly changed by performing with a constant volume (before water was added as an additive, while the ethanol quantities were kept constant) and under inherent pressure. Even with these slight changes, similar results were observed - the addition of water reduces the rate of the reaction but increases the butanol selectivity. Figures 3 and 4 are conversion-time diagrams for different water quantities without solvent. Figure 3 shows the selectivity-conversion diagram for different water quantities without solvent using the above catalyst system. The reaction conditions were: Indicated amount of ethanol, 0.015 mol% Ru(acac)3, 0.03 mol% Cy-Acr-PNP, 3 mol% KOEt, indicated amount of water, inherent pressure, 150 °C.

[0192] Figures 5 and 6 illustrate the conversion-time diagrams for different water quantities using the second catalyst system. Figures 5 and 6 show the selectivity-conversion diagrams for different water quantities using the second ligand system. The reaction conditions were: Indicated amount of ethanol, 0.015 mol% Ru(acac)s, 0.03 mol% IPr-Acr-PNP, 3 mol% KOEt, indicated amount of water, inherent pressure, 150 °C.

[0193] Cited literature:

[0194] M. Guerbet, C. R. Hebd. Seances Acad. Sei. 1899, 128, p. 511-513

[0195] - WO 2015 / 031561 A1

[0196] - 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

[0197] - WO 2013 / 156399 A1

[0198] N. Biswas at 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

Claims

Ciaims1 . 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 R-CH2-CH2-OH, a base, water, and the component C provided according to (i), R being selected from the group consisting of H and Ci-C4-alkyl;(iii) subjecting the liquid mixture ME prepared 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 R-CH2-CH2-(CHR-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 MG in 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; wherein the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol R-CH2-CH2-OH;(iv) separating at least a part of said at least one unreacted alcohol R-CH2-CH2-OH from the liquid reaction mixture MG;(v) separating the at least one alcohol R-CH2-CH2-(CHR-CH2)X-OH from the reaction mixture MG obtained according to (iii), obtaining the at least one alcohol R-CH2- CH2-(CHR-CH2)X-OH and a mixture Mos;(vi) recycling at least a part of the at least one unreacted alcohol R-CH2-CH2-OH obtained according to (iv) to (ii) or (iii); 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 liquid mixture ME according to (ii) comprises an amount of the water in the liquid mixture ME in the range of from 0.5 to 25 weight-%, based on the total weight of the liquid mixture ME;(c) the alcohol conversion conditions according to (iii) comprise an amount of the water in the reaction mixture MG in the range of from 0.5 to 25 weight-%, based on the total weight of the reaction mixture MG;(d) 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, PRaRb, NRaRb, SRa, SH, S(=O)Rd, C5- Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, and a N -heterocyclic carbene represented by the structures:L3is selected from the group consisting of CO, PRaRbRc, AsRaRbRc, SbRaRbRc, SRaRb, RdCN, RdNC, 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 catalyst 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, NRd2, NH3, NRd3, and Rd2NSO2Rd;Ra, Rb, Rc, Rd, R5, R6and R7are, 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 Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted Cs-C -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 -alkyl; unsubstituted or substituted Cs-C -aryl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; and unsubstituted or substituted Cs-C -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 -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-C -alkyl; and(e) the precursor of the catalyst comprising a compound of formula (A) comprises 1) a mixture comprising a compound comprising a metal M; 2) at least one component selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, N2, PF3, organic carbonyl compounds, Ci-C -alkyl, C3-Ci2-cycloalkyl, C2- Ci2-alkenyl, Cs-C-is-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, PRaRb, NRaRb, SRa, SH, S(=O)Rd, Cs-Cio-heteroaryl containing at least one heteroatom selected from nitrogen and sulfur, AsRaRb, SbRaRb, 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 ;Ra, Rb, Rc, Rd, R5, R6and R7are, 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 Cs-C -cycloalkyl, wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; unsubstituted or substituted Cs-C -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 -alkyl; unsubstituted or substituted Cs-C -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-C -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-Cio-alkyl; andX is an integer 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- % of the liquid mixture ME prepared according to (ii) consist of the at least one alcohol R-CH2-CH2-OH, the base, water and the component C.

3. The process of claim 1 or 2, wherein the liquid mixture ME according to (ii) comprises an amount of the water in the liquid mixture ME in the range of from 4 to 11 weight-%, based on the total weight of the liquid mixture ME.

4. The process of any one of claims 1 to 3, wherein the alcohol conversion conditions according to (iii) comprise an amount of water in the reaction mixture MG in the range of from 4 to 11 weight-%, based on the total weight of the reaction mixture MG.

5. The process of any one of claims 1 to 4, wherein the reaction space SG according 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.

6. The process of claim 5, 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.

7. The process of any one of claims 1 to 6, 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, PRaRbRc, SRaRb, RaCN, RaNC, 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, PRaRb, NRaRb, SRa, SH, and S(=O)Rd; L3is selected from the group consisting of CO, PRaRbRc, SRaRb, RaCN, RaNC, 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;Ra, Rb, Rcand Rd, 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 Cs-C -cycloalkyl wherein the substituents are selected from the group consisting of F, Cl, Br, OH, CN, NH2, and Ci-C -alkyl; Cs-C -heterocycle comprising at least one heteroatom selected from the group consisting of N, O, and S; Cs-C -aryl; and Cs-C -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.

8. The process of any one of claims 1 to 7, wherein the component C comprises a compound of formula (D) wherein Cy is cyclohexyl;wherein the component C comprises a compound of formula (E)wherein iPr is isopropyl; or wherein the component C comprises a compound of formula (F)wherein tBu is tert-butyl.

9. The process of any one of claims 1 to 8, wherein integer x is 1 or 2.

10. The process of any one of claims 1 to 9, wherein R is selected from the group consisting of H, methyl, ethyl, propyl, and isopropyl.11 . The process of any one of claims 1 to 10, wherein the liquid mixture ME prepared according to (ii) further comprises a compound of formula (G)wherein R1, R2, R3and R4, L1, L2, and n as defined above.

12. The process of claim 11 , 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) relative to the component C is in the range of from 1 :1 to 10:1.

13. The process of any one of claims 1 and 3 to 12, wherein the liquid mixture ME according to (ii) further comprises a solvent component which comprises one or more solvents.

14. The process of claim 13, wherein the one or more solvents of the solvent component have a boiling point at 1 atm (101325 Pa) of 140 °C or more.

15. The process of any one of claims 1 to 14, wherein the liquid reaction mixture MG obtained according to (iii) further comprises at least one unreacted alcohol R-CH2-CH2- OH, the process further comprising separating at least a part of said unreacted alcohol from the liquid reaction mixture MG, wherein at least a part of the at least one unreactedalcohol separated from MG is recycled to (ii) or (ill), wherein (iv) separating at least a part of said unreacted alcohol R-CH2-CH2-OH from the liquid reaction mixture MG comprises separation of the unreacted alcohol R-CH2-CH2-OH in form of a mixture of said alcohol with water, wherein the amount of water is from 2 to 20 weight-%.

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