Selective Hydrogenation

Abstract

The present invention relates to the use of certain homogeneous catalysts for the partial (selective) hydrogenation of carbon-carbon triple bonds, i.e., for the hydrogenation of alkynes to alkenes.

Description

Detailed Description of the Invention

[0001] The present invention relates to the use of certain homogeneous catalysts for the partial (selective) hydrogenation of carbon-carbon triple bonds.

[0002] This catalyst is used for selective hydrogenation, i.e., hydrogenating alkynes to alkenes. Thus, in the case of compounds containing a double bond in addition to a triple bond, only the triple bond is reduced to a double bond.

[0003] Homogeneous catalysis refers to reactions in which the catalyst is in the same phase as the reactants, primarily in solution.

[0004] The purpose of this study was to improve the selectivity of selective hydrogenation reactions using such catalysts.

[0005] It has been found that transition metal catalysts bearing specific bidentate phosphine ligand systems exhibit good hydrogenation efficiency under mild reaction conditions.

[0006] The catalyst used in the selective hydrogenation according to the present invention has the following formula (I): [M + (L1)(L2) n ]X (I) (In the formula, M is Rh or Ir; L1 is a group represented by the formula (II): (R)2-PAP-(R 1 )2(II) (In the formula, R is substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl, or isopropyl; R 1 is substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl, or isopropyl; A is: ---(CH2) m--- (wherein m is an integer having a value from 1 to 6); and [ka] (wherein z is 0 or 1) wherein the bridging moiety is selected from the group consisting of: L2 is a bidentate or monodentate ligand; however, When L2 is a bidentate ligand, n is 1 and L2 is not a bidentate ligand of formula (II), When L2 is a monodentate ligand, n is 2; X is an anion; Any dotted lines in the formula represent the bond attaching the substituent to the remainder of the molecule.

[0007] The catalysts of the present invention are used for the selective catalytic hydrogenation of starting materials, in particular starting materials containing carbon-carbon triple bonds, more particularly alkynol compounds, particularly preferably α-alkynol compounds.

[0008] The present invention therefore provides in a first aspect a process for selective hydrogenation (H), comprising the step of reacting at least one compound of formula (I): [M + (L1)(L2) n ]X (I) (In the formula, M is Rh or Ir; L1 is a group represented by the formula (II): (R)2-PAP-(R 1 )2(II) (In the formula, R is substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl, or isopropyl; R 1is substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl, or isopropyl; A is: ---(CH2) m --- (wherein m is an integer having a value from 1 to 6); and [ka] (wherein z is 0 or 1) wherein the bridging moiety is selected from the group consisting of: L2 is a bidentate or monodentate ligand; however, When L2 is a bidentate ligand, n is 1 and L2 is not a bidentate ligand of formula (II), When L2 is a monodentate ligand, n is 2; X is an anion The present invention relates to a process comprising the step of selectively hydrogenating an alkyne to an alkene in the presence of a catalyst of formula (I).

[0009] The catalyst of formula (I) is a homogeneous catalyst.

[0010] Thus, the present invention also relates to a process for selective hydrogenation (H), a process for selective hydrogenation (H1), in which a starting material containing a carbon-carbon triple bond is selectively hydrogenated.

[0011] The present invention therefore also relates to a process for selective hydrogenation (H2), which is a process for selective hydrogenation (H) or (H1), in which alkynol compounds are selectively hydrogenated.

[0012] Therefore, the present invention also relates to a process for selective hydrogenation (H2'), which is a process for selective hydrogenation (H) or (H1), in which α-alkynol compounds are selectively hydrogenated.

[0013] Preferably, the present invention also provides a compound of formula (III): [ka] (In the formula, R 2 is a straight or branched C1 to C 35 -Alkyl moiety; or linear or branched C2-C 35 - an alkenyl moiety, the carbon chain of which may be substituted; R 3 is H or a linear or branched C1-C4 alkyl, the carbon chain of which may be substituted; R 4 is H or a cyclic, straight-chain or branched C1-C6 alkyl whose carbon chain may be substituted; or an optionally substituted C5-C 12 - a cyclic aromatic moiety, R 5 also relates to a process for the selective hydrogenation of compounds in which the alkyl group is H or OH or O(CO)C1-C4-alkyl or O(CO)C1-C4-alkyl.

[0014] The product of the selective hydrogenation is represented by formula (IV): [ka] (In the formula, R 2 , R 3 , R 4 and R 5 is the same as defined in formula (III).

[0015] More preferably, the present invention also provides a process for selective hydrogenation comprising the steps of: [ka] (In the formula, R 2 is a straight or branched C1 to C 30 -Alkyl moiety; or linear or branched C2-C30 - an alkenyl moiety, the carbon chain of which may be substituted; R 3 is C1-C2-alkyl, R 4 is H or linear or branched C1-C6 alkyl, the carbon chain of which may be substituted; R 5 is OH or OC1-C2-alkyl), Formula (IV): [ka] The present invention also relates to a process for selectively hydrogenating a compound of formula (I) to a compound of formula (II).

[0016] More preferably, the present invention also provides a process for selective hydrogenation comprising the steps of: [ka] (In the formula, R 2 is a straight or branched C1 to C 20 -Alkyl moiety; or linear or branched C2-C 20 -alkenyl moiety, The carbon chain may be substituted; R 3 is C1-C2-alkyl, R 4 is H, R 5 is OH or O(CO)C1-C2-alkyl) Formula (IV): [ka] The present invention also relates to a process for selectively hydrogenating a compound of formula (I) to a compound of formula (II).

[0017] The most preferred compounds of formula (III) are those of the following formulae (IIIa) to (IIId): [ka] It has the following characteristics.

[0018] Therefore, the present invention also provides a process for selective hydrogenation (H3), which is a process for selective hydrogenation (H), (H1) or (H2), comprising the reaction of formula (III): [ka] (In the formula, R 2 is a straight or branched C1 to C 35 -Alkyl moiety; or straight or branched C2-C 35 -alkenyl moiety, The carbon chain may be substituted; R 3 is H; linear or branched C1-C4 alkyl, the carbon chain of which may be substituted; R 4 is H; cyclic, straight-chain or branched C1-C6 alkyl whose carbon chain may be substituted; or optionally substituted C5-C 12 - a cyclic aromatic moiety, R 5 is H or OH or OC1-C4-alkyl or O(CO)C1-C4-alkyl), Formula (IV): [ka] The present invention also relates to a process for selectively hydrogenating a compound of formula (I) to a compound of formula (II).

[0019] Therefore, the present invention also provides a process for selective hydrogenation (H3′), which is a process for selective hydrogenation (H), (H1), (H2) or (H2′), comprising the reaction of formula (III): [ka] (In the formula, R 2 is a straight or branched C1 to C 30-Alkyl moiety; or straight or branched C2-C 30 -alkenyl moiety, The carbon chain may be substituted; R 3 is C1-C2-alkyl, R 4 is H; cyclic, linear or branched C1-C6 alkyl, the carbon chain of which may be substituted; R 5 is OH or O(CO)C1-C2-alkyl) Formula (IV): [ka] The present invention also relates to a process for selectively hydrogenating a compound of formula (I) to a compound of formula (II).

[0020] Therefore, the present invention also provides a process for selective hydrogenation (H3″), which is a process for selective hydrogenation (H), (H1), (H2) or (H2′), comprising the reaction of formula (III): [ka] (In the formula, R 2 is a straight or branched C1 to C 20 -Alkyl moiety; or linear or branched C2-C 20 -alkenyl moiety, The carbon chain may be substituted; R 3 is C1-C2-alkyl, R 4 is H, R 5 is OH or O(CO)C1-C2-alkyl) Formula (IV): [ka] The present invention also relates to a process for selectively hydrogenating a compound of formula (I) to a compound of formula (II).

[0021] Thus, the present invention also provides a process for selective hydrogenation (H3'''), which is a process for selective hydrogenation (H), (H1), (H2) or (H2'), comprising a compound represented by formula (IIIa), (IIIb), (IIIc) or (IIId): [ka] is represented by formula (IVa), (IVb), (IVc) or (IVd), respectively: [ka] The present invention also relates to a process for selectively hydrogenating a compound of formula (I) to a compound of formula (II).

[0022] As stated above, the selective hydrogenation according to the present invention is carried out using a specific catalyst of formula (I).

[0023] Preferred catalysts of formula (I) are those in which M is Rh.

[0024] Therefore, the present invention also relates to a process for selective hydrogenation (H4), which is a process for selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3") or (H3'"), in which a catalyst of formula (I) in which M is Rh is used.

[0025] Preferred catalysts of formula (I) are those in which L1 is a compound of the following formulae (IIa) to (IIp): [ka] [ka] The ligand is a bidentate phosphine ligand selected from the group consisting of:

[0026] More preferred catalysts of formula (I) are those in which L1 is of the formula: [ka] The ligand is a bidentate phosphine ligand selected from the group consisting of:

[0027] The present invention therefore also provides a process for selective hydrogenation (H5), which is a process for selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'") or (H4), wherein L1 is a compound of formula (IIa) to (IIp): [ka] [ka] The present invention also relates to a process wherein a catalyst of formula (I) is used which is a bidentate phosphine ligand selected from the group consisting of ligands of formula (I):

[0028] The present invention therefore also relates to a process for selective hydrogenation (H5') of a hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'") or (H4), comprising: L1 is a ligand: [ka] The present invention also relates to a process wherein a catalyst of formula (I) is used which is a bidentate phosphine ligand selected from the group consisting of:

[0029] Preferred catalysts are those in which L2 is a bidentate ligand selected from the group consisting of cyclohexadiene, cycloheptadiene, 1,5-cyclooctadiene (COD), norbornadiene (NBD), and n is 1.

[0030] Therefore, the present invention also relates to a process for selective hydrogenation (H6), which is a process for selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5) or (H5'), in which a catalyst of formula (I) is used, wherein L2 is a bidentate ligand selected from the group consisting of cyclohexadiene, cycloheptadiene, 1,5-cyclooctadiene (COD) and norbornadiene (NBD), and n is 1.

[0031] When L2 is a monodentate ligand, n=2, ie the catalyst of formula (I) has two identical monodentate ligands.

[0032] Therefore, further preferred catalysts are those in which L2 is a monodentate ligand selected from the group consisting of R6OH (R6 is a linear or branched C1-C8 alkyl moiety); cyclooctene, cycloheptene, cyclohexene, norbornene and ethene, and n is 2. Particularly preferably, the carbonyl is not a monodentate ligand L2.

[0033] Therefore, the present invention also relates to a process for selective hydrogenation (H7), which is a process for selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5) or (H5'), in which a catalyst of formula (I) is used, wherein L2 is R6OH (R6 is a linear or branched C1-C8 alkyl moiety); a monodentate ligand selected from the group consisting of cyclooctene, cycloheptene, cyclohexene, norbornene and ethene, and n is 2.

[0034] Preferred catalysts are those in which X is a halide (Cl - , I - , Br - , F - etc.), BF4 - , PF6 - , tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] -), (Ph)4B - , ClO4 - , TfO - or SbF6 - TfO - is a triflate (=trifluoromethanesulfonate).

[0035] A more preferred catalyst is one in which X is BF4 - , PF6 - , tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] - ), (Ph)4B - , ClO4 - , TfO - or SbF6 - It is what it is.

[0036] Therefore, the present invention also relates to a process for selective hydrogenation (H8), which is a selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6) or (H7), wherein X of the catalyst of formula (I) is a halide (Cl - , I - , Br - , F - etc.), BF4 - , PF6 - , tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] - ), (Ph)4B - ClO4 - , TfO - and SbF6 - The present invention also relates to a process wherein the compound is selected from the group consisting of:

[0037] The present invention therefore also provides a process for selective hydrogenation (H8'), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6) or (H7), wherein X of the catalyst of formula (I) is BF4 - , PF6 -, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BAr F 4] - ), (Ph)4B - ClO4 - , TfO - and SbF6 - The present invention also relates to a process wherein the compound is selected from the group consisting of:

[0038] The catalysts used in the hydrogenation according to the present invention are prepared as disclosed in the prior art.

[0039] The hydrogenation according to the present invention can be carried out without a solvent.

[0040] The present invention therefore also relates to a process for selective hydrogenation (H9), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8) or (H8'), wherein the hydrogenation is carried out without the use of a solvent.

[0041] The hydrogenation according to the invention can be carried out in the presence of at least one inert solvent.

[0042] The hydrogenation can be carried out in a solvent (or a mixture of solvents). Suitable solvents are alkanes, esters, carbonates, lactones, ethers, amides, hydrocarbons, halogenated hydrocarbons, water, and alcohols. Preferred solvents are water, hexane, CHCl, toluene, ethyl acetate, THF (= tetrahydrofuran), 2-Me-THF (= 2-methyl-tetrahydrofuran), cyclopentyl methyl ether (= CPME), methanol, ethanol, and isopropanol, and particularly preferred solvents are methanol, water, and hexane.

[0043] The present invention therefore also relates to a process for selective hydrogenation (H10), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8) or (H8'), wherein the hydrogenation is carried out in at least one solvent.

[0044] Therefore, the present invention also relates to a process for selective hydrogenation (H10), a process for selective hydrogenation (H10'), wherein the solvent is selected from the group consisting of alkanes, esters, carbonates, lactones, ethers, amides, hydrocarbons, halogenated hydrocarbons, water and alcohols.

[0045] Therefore, the present invention also relates to a process for selective hydrogenation (H10), wherein the solvent is selected from the group consisting of water, hexane, CHCl, toluene, ethyl acetate, THF, 2-Me-THF, cyclopentyl methyl ether, methanol, ethanol, and isopropanol.

[0046] Therefore, the present invention also relates to a process for selective hydrogenation (H10), wherein the solvent is selected from the group consisting of methanol, water and hexane.

[0047] The catalyst of formula (I) according to the present invention is usually used in an amount of 0.001 to 1 mol % (preferably 0.001 to 0.5 mol %) (based on the number of moles of the compound of formula (III)).

[0048] Therefore, the present invention also relates to a process for selective hydrogenation (H11), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8), (H8'), (H9), (H10), (H10'), (H10") or (H10'"), wherein the at least one catalyst of formula (I) is used in an amount of 0.001 to 1 mol % (based on the number of moles of the compound of formula (III)).

[0049] The present invention therefore also relates to a process for selective hydrogenation (H11'), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8), (H8'), (H9), (H10), (H10'), (H10") or (H10'"), wherein the at least one catalyst of formula (I) is used in an amount of 0.001 to 0.5 mol % (based on the number of moles of the compound of formula (III)).

[0050] The hydrogenation process can be carried out using (pure) H2 gas or using a gas containing H2. Preferably, the hydrogenation according to the present invention can be carried out using (pure) H2 gas.

[0051] Therefore, the present invention also relates to a process for selective hydrogenation (H12), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8), (H8'), (H9), (H10), (H10'), (H10"), (H10'"), (H11) or (H11'), wherein the hydrogenation is carried out using (pure) H2 gas or using a gas comprising H2.

[0052] Thus, the present invention also relates to a process for selective hydrogenation (H12'), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8), (H8'), (H9), (H10), (H10'), (H10"), (H10'"), (H11) or (H11'), wherein the hydrogenation is carried out using H2 gas.

[0053] The hydrogenation process can be carried out at normal pressure or at elevated pressure. Preferably, the hydrogenation process according to the invention is carried out at a pressure of 1 to 50 bar, more preferably 1 to 30 bar. Usually, the reaction is carried out in an autoclave (or any other pressure-resistant vessel).

[0054] Thus, the present invention also relates to a process for selective hydrogenation (H13), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8), (H8'), (H9), (H10), (H10'), (H10"), (H10'"), (H11), (H11'), (H12) or (H12'), wherein the hydrogenation is carried out at atmospheric pressure.

[0055] The present invention therefore also relates to a process for selective hydrogenation (H13'), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8), (H8'), (H9), (H10), (H10'), (H10"), (H10'"), (H11), (H11'), (H12) or (H12'), wherein the hydrogenation is carried out at a pressure of from 1 to 50 bar, preferably from 1 to 30 bar.

[0056] The hydrogenation is usually carried out at a temperature of −10 to 150° C. (preferably 10 to 100° C.).

[0057] Thus, the present invention also relates to a process for selective hydrogenation (H14), which is a process of selective hydrogenation (H), (H1), (H2), (H2'), (H3), (H3'), (H3"), (H3'"), (H4), (H5), (H5'), (H6), (H7), (H8), (H8'), (H9), (H10), (H10'), (H10"), (H10'"), (H11), (H11'), (H12), (H12'), (H13) or (H13'), wherein the hydrogenation is carried out at a temperature of from -10 to 150°C.

[0058] The following examples serve to illustrate the invention, temperatures are given in °C and all percentages are by weight.

[0059] [Example] [General catalyst synthesis (Example 1)] Rh(COD)acac (1 mmol) was dissolved in THF (3 mL) and the reaction mixture was cooled to -78 °C. The ligand (1.0 eq) dissolved in THF (7 mL) was added dropwise over 30 min, followed by the addition of HBF (125 μl (50% in HO). The catalyst was then participated with diethyl ether (40 mL), filtered, washed with diethyl ether, and dried.

[0060] All other catalysts used in the following examples were prepared in a similar manner to the process of Example 1.

[0061] [Hydrogenation Example] Example 2: Hydrogenation reaction An autoclave was charged with 440 mmol of dehydroisophytol (compound of formula (IIIb) = DIP), 650 ml of methanol, and 4.4 mmol of [Rh(cyc-Japhos)(NBD)]BF prepared as described in Example 1. After stirring the mixture, H was added in the form of H gas.

[0062] The autoclave was temperature-controlled at 25°C, and after the desired reaction time had elapsed, the hydrogen pressure was released. The analytical results of the reaction mixture are shown in Table 1 (No. 1).

[0063] The following examples were carried out following the same process as in Example 2 (Tables 1-3 list the differences in reaction conditions).

[0064] [Table 1]

[0065] [Table 2]

[0066] [Table 3]

Claims

1. A process for selective hydrogenation comprising reacting at least one compound of formula (I): [M] ＋ (L1) (L2) ｎ ]X (I) (In the formula, M is Rh or Ir; L1 is a group represented by formula (II): (2) ２ ______________________________ １ ) ２ (=) (In the formula, R is substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl, or isopropyl; R １ is substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl, or isopropyl; A is: ---(CH ２ ) ｍ --- (wherein m is an integer having a value from 1 to 6); and 【Chemistry 1】 (wherein z is 0 or 1) and wherein the bridging moiety is selected from the group consisting of: L2 is a bidentate or monodentate ligand; however, When L2 is a bidentate ligand, n is 1 and L2 is not a bidentate ligand of formula (II), When L2 is a monodentate ligand, n is 2; X is an anion; (Any dotted lines in the formula represent the bond connecting the substituent to the remainder of the molecule.)

2. 10. The process of claim 1, wherein a starting material containing a carbon-carbon triple bond is selectively hydrogenated.

3. Formula (III): 【Chemistry 2】 (In the formula, R ２ is a linear or branched C １ ~C ３５ - an alkyl moiety; or a linear or branched C ２ ~C ３５ - an alkenyl moiety, The carbon chain may be substituted; R ３ is H; linear or branched C １ ~C ４ - alkyl, the carbon chain of which may be substituted; R ４ is H; a cyclic, linear or branched C １ ~C ６ -alkyl; or optionally substituted C ５ ~C １２ - a cyclic aromatic moiety, R ５ is H or OH or OC １ ~C ４ -Alkyl or O(CO)C １ ~C ４ -alkyl) Formula (IV): 【Transformation 3】 3. The process of claim 1 or claim 2, wherein the compound is selectively hydrogenated to a compound of formula:

4. Formula (III): 【Chemistry 4】 (In the formula, R ２ is a linear or branched C １ ~C ２０ - an alkyl moiety; or a linear or branched C ２ ~C ２０ - an alkenyl moiety, The carbon chain may be substituted; R ３ is C １ ~C ２ - alkyl, R ４ is H, R ５ is OH or O(CO)C １ ~C ２ -alkyl) Formula (IV): 【Transformation 5】 The process according to any one of claims 1 to 3, wherein the compound is selectively hydrogenated to a compound of formula (I).

5. 5. The process according to any one of claims 1 to 4, wherein a catalyst of formula (I) is used in which M is Rh.

6. of the catalyst of formula (I), L1 is a compound represented by the formula (IIa) to (IIp): 【Transformation 6】 【Transformation 7】 【Transformation 8】 The process of any one of claims 1 to 5, wherein the bidentate phosphine ligand is selected from the group consisting of:

7. 7. The process according to any one of claims 1 to 6, wherein a catalyst of formula (I) is used, wherein L2 is a bidentate ligand selected from the group consisting of cyclohexadiene, cycloheptadiene 1,5-cyclooctadiene (COD) and norbornadiene (NBD), and n is 1.

8. L2 is R ６ OH (R ６ is a linear or branched C １ ~C ８ - is an alkyl moiety; 7. The process according to any one of claims 1 to 6, wherein a catalyst of formula (I) is used, wherein n is 2 and the ligand is a monodentate ligand selected from the group consisting of cyclooctene, cycloheptene, cyclohexene, norbornene and ethene.

9. In the catalyst of formula (I), X is a halide (Cl － , I － ,Br － , F － etc.), BF ４ － , P.F. ６ － , tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BAr Ｆ ４ ] － ), (Ph) ４ B － , ClO ４ － , TfO － and SbF ６ － The process of any one of claims 1 to 8, wherein the compound is selected from the group consisting of:

10. 10. The process of any one of claims 1 to 9, wherein the hydrogenation is carried out without the use of a solvent.

11. The process of any one of claims 1 to 9, wherein the hydrogenation is carried out in at least one solvent.

12. 12. The process according to any one of claims 1 to 11, wherein the at least one catalyst of formula (I) is used in an amount of 0.001 to 1 mol % (based on the number of moles of the compound of formula (III)).

13. The hydrogenation is carried out using (pure) H ２ gas or H ２ The process of any one of claims 1 to 12, carried out using a gas comprising

14. The process according to any one of claims 1 to 13, wherein the hydrogenation is carried out at a pressure of from 1 to 50 bar.

15. The process of any one of claims 1 to 14, wherein the hydrogenation is carried out at a temperature of from -10 to 150°C.

16. 16. The process according to any one of claims 1 to 15, characterized in that the catalyst of formula (I) has M=Rh.

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