Selective hydrogenation

Abstract

The present invention relates to the use of a specific homogenous catalyst for the partial (selective) hydrogenation of a carbon-carbon triple bond, i.e. of alkynes to alkenes.

Description

[0001] Selective Hydrogenation

[0002] The present invention relates to the use of a specific homogenous catalyst for the partial (selective) hydrogenation of a carbon-carbon triple bond.

[0003] The catalyst is used for the selective hydrogenation, i.e. for the hydrogenation of alkynes to alkenes. Thus, if a compound contains a double bond as well as a triple bond, only the triple bond is reduced to a double bond.

[0004] Homogeneous catalysis refers to reactions where the catalyst is in the same phase as the reactants, principally in solution.

[0005] The aim of the present work was to improve the selectivity of selective hydrogenation reactions catalyzed by such catalysts.

[0006] It was found out that the transition metal catalyst with a specific bidentate phosphine ligand system shows a good efficiency of the hydrogenation while using mild reaction conditions.

[0007] The catalyst used in the selective hydrogenation according to the present invention has the following formula (I)

[0008] [M+(L1)(L2)n]X (I), wherein

[0009] M is Rh or Ir, and

[0010] L1 is a bidentate phosphine ligand of formula (II) (R)2-P-A-P-(R1)2(II), wherein

[0011] R is a substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl or isopropyl, and

[0012] R1is a substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl or isopropyl, and

[0013] A is a bridging moiety chosen from the group consisting of

[0014] ■■■(CH2)m---werein m is an integer of value 1 - 6; wherein z is 0 or 1 , and

[0015] L2 is a bidentate ligand or a monodentate ligand, with the proviso that when L2 is a bidentate ligand, then n is 1 and L2 is not a bidentate ligand of formula

[0016] (II) when L2 is a monodentate ligand, then n is 2, and

[0017] X is an anion; and wherein any dotted line in formulae represents the bond by which the substituent is bound to the rest of the molecule.

[0018] The catalyst of the present invention is used in selective catalytic hydrogenation of starting material, especially of starting material comprising a carbon-carbon triple bond, more especially of alkynol compounds, especially preferred a-alkynol compounds.

[0019] Therefore, the present invention relates in a first aspect, to a process of selective hydrogenation (H) comprising the step of selectively hydrogenating alkynes to alkenes in the presence of at least one catalyst of formula (I)

[0020] [M+(L1)(L2)n]X (I), wherein

[0021] M is Rh or Ir, and

[0022] L1 is a bidentate phosphine ligand of formula (II)

[0023] (R)2-P-A-P-(R1)2(II), wherein

[0024] R is a substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl or isopropyl, and

[0025] R1is a substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl or isopropyl, and

[0026] A is a bridging moiety chosen from the group consisting of integer of value 1 - 6;

[0027] And wherein z is 0 or 1 , and

[0028] L2 is bidentate ligand or a monodentate ligand, with the proviso that when L2 is a bidentate ligand, then n is 1 and L2 is not a bidentate ligand of formula (II) when L2 is a monodentate ligand, then n is 2, and

[0029] X is an anion.

[0030] The catalyst of the formula (I) is a homogenous catalyst.

[0031] Therefore, the present invention also relates to a process of selective hydrogenation (H1), which is the process of selective hydrogenation (H), wherein starting material comprising a carbon-carbon triple bond are hydrogenated selectively.

[0032] Therefore, the present invention also relates to a process of selective hydrogenation (H2), which is the process of selective hydrogenation (H) or (H1), wherein alkynol compounds are hydrogenated selectively. Therefore, the present invention also relates to a process of selective hydrogenation (H2’), which is the process of selective hydrogenation (H) or (H 1), wherein a-alkynol compounds are hydrogenated selectively.

[0033] Preferably, the present invention also relates to a process of selective hydrogenation of a compound of formula (III)

[0034] R5

[0035] R4C=C - C - R3(Hl)

[0036] R2wherein

[0037] R2is a linear or branched Ci-Css-alkyl; or a linear or branched C2-C35-alkenyl moiety, wherein the C chain can be substituted, and

[0038] R3is H or a linear or branched Ci-C4-alkyl, wherein the C chain can be substituted, and

[0039] R4is H or a cyclic, linear or branched Ci-Ce-alkyl, wherein the C chain can be substituted; or a Cs- C12- cyclic aromatic moiety, which can be substituted, and

[0040] R5is H or OH or a OCi-C4-alkyl; or a O(CO)Ci-C4-alkyl.

[0041] The product of the selective hydrogenation is the compound of formula (IV) wherein

[0042] R2, R3, R4and R5have the same meaning as defined in formula (III).

[0043] More preferably, the present invention also relates to a process of selective hydrogenation wherein a compound of formula (III)

[0044] R5

[0045] R4C=C - C - R3(Hl)

[0046] R2wherein

[0047] R2is a linear or branched Ci-Cso-alkyl; or a linear or branched C2-Cso-alkenyl moiety, wherein the C chain can be substituted, and R3is a Ci-C2-alkyl, and

[0048] R4is H or a linear or branched Ci-Ce-alkyl, wherein the C chain can be substituted, and

[0049] R5is OH or a OCi-C2-alkyl is hydrogenated selectively to a compound of the formula (IV)

[0050] Even more preferably, the present invention also relates to a process of selective hydrogenation wherein of a compound of formula (III)

[0051] R5

[0052] R4C=C - C - R3(H l)

[0053] R2wherein

[0054] R2is a linear or branched Ci-C2o-alkyl; or a linear or branched C2-C2o-alkenyl moiety, wherein the C chain can be substituted, and

[0055] R3is a Ci-C2-alkyl, and

[0056] R4is H, and R5is OH or a O(CO)Ci-C2-alkyl is hydrogenated selectively to a compound of the formula (IV)

[0057] Most preferred compounds of formula (III) are the following of formula (Illa) to (Hid)

[0058] Therefore, the present invention also relates to a process of selective hydrogenation (H3), which is the process of selective hydrogenation (H), (H1) or (H2), wherein a compound of formula (III)

[0059] R5

[0060] R4C=C - C - R3(Hl)

[0061] R2wherein

[0062] R2is a linear or branched Ci-Css-alkyl; or a linear or branched C2-C35-alkenyl moiety, wherein the C chain can be substituted, and

[0063] R3is H; linear or a branched Ci-C4-alkyl, wherein the C chain can be substituted, and

[0064] R4is H; cyclic, a linear or branched Ci-Ce-alkyl, wherein the C chain can be substituted; or a C5- Ci2-cyclic aromatic moiety, which can be substituted, and

[0065] R5is H or OH or a OCi-C4-alkyl or a O(CO)Ci-C4-alkyl, is hydrogenated selectively to a compound of the formula (IV)

[0066] Therefore, the present invention also relates to a process of selective hydrogenation (H3’), which is the process of selective hydrogenation (H), (H1), (H2) or (H2’), wherein a compound of formula (III)

[0067] R5

[0068] R4C=C - C - R3(H l)

[0069] R2wherein

[0070] R2is a linear or branched Ci-Cso-alkyl; or a linear or branched C2-Cso-alkenyl moiety, wherein the C chain can be substituted, and

[0071] R3is a Ci-C2-alkyl, and

[0072] R4is H; a cyclic, linear or branched Ci-Ce-alkyl, wherein the C chain can be substituted, and

[0073] R5is OH or a O(CO)Ci-C2-alkyl, is hydrogenated selectively to a compound of the formula (IV)

[0074] Therefore, the present invention also relates to a process of selective hydrogenation (H3”), which is the process of selective hydrogenation (H), (H1), (H2) or (H2’), wherein a compound of formula (III)

[0075] R5

[0076] R4C=C - C - R3(H l)

[0077] R2wherein

[0078] R2is a linear or branched Ci-C2o-alkyl; or a linear or branched C2-C2o-alkenyl moiety, wherein the C chain can be substituted, and

[0079] R3is a Ci-C2-alkyl, and

[0080] R4is H, and

[0081] R5is OH or a O(CO)Ci-C2-alkyl, is hydrogenated selectively to a compound of the formula (IV)

[0082] Therefore, the present invention also relates to a process of selective hydrogenation (H3’”), which is the process of selective hydrogenation (H), (H1), (H2) or (H2’), wherein a com- pound of formula (Illa), (I lib), (I He) or (Hid) is hydrogenated selectively to a compound of the formula (IVa), (I b), (IVc) or (IVd), respectively

[0083] As stated above, the selective hydrogenation according to the present invention is carried out using a specific catalyst of formula (I).

[0084] Preferred catalysts of formula (I) are those, wherein M is Rh.

[0085] Therefore, the present invention also relates to a process of selective hydrogenation (H4), which is the process of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”) or (H3’”), wherein a catalyst of formula (I), wherein M is Rh is used. Preferred catalysts of formula (I) are those, wherein L1 is a bidentate phosphine ligand chosen from the group consisting of the following ligands of formulae (Ila) to (lip) More preferred catalysts of formula (I) are those, whereinLI is a bidentate phosphine ligand chosen from the group consisting of the following ligands of formulae Therefore, the present invention also relates to a process of selective hydrogenation (H5), which is the process of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3’”) or (H4), wherein a catalyst of formula (I), wherein L1 is a bidentate phosphine ligand chosen from the group consisting of the ligands of formula (Ila) to (lip)

[0086]

[0087] 5 is used. Therefore, the present invention also relates to a process of selective hydrogenation (H5’), which is the hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3’”) or (H4), wherein a catalyst of formula (I), wherein

[0088] L1 is a bidentate phosphine ligand chosen from the group consisting of the ligands is used.

[0089] Preferred catalysts are those wherein L2 is bidentate ligand chosen from the group consisting of cyclohexadiene, cycloheptadiene 1 ,5-cyclooctadiene (COD), norbornadiene (NBD), and n is 1.

[0090] Therefore, the present invention also relates to a process of selective hydrogenation (H6), which is the process of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3’”), (H4), (H5) or (H5’), wherein a catalyst of formula (I), wherein L2 is bidentate ligand chosen from the group consisting of cyclohexadiene, cycloheptadiene, 1 ,5-cyclooctadiene (COD) and norbornadiene (NBD) and n is 1 is used.

[0091] In case L2 is a monodentate ligand, then n = 2, i.e. that the catalyst of the formula (I) has two identical monodentate ligands.

[0092] Therefore, further preferred catalysts are those wherein L2 is a monodentate ligand chosen from the group consisting of ReOH, wherein Re is a linear or branched Ci - Cs-alkyl moiety; cyclooctene, cycloheptene, cyclohexene, norbornene and ethene and n is 2.

[0093] It is particularly preferred that carbonyl is not a monodentate ligand L2.

[0094] Therefore, the present invention also relates to a process of selective hydrogenation (H7), which is the process of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3’”), (H4), (H5) or (H5’), wherein a catalyst of formula (I), wherein L2 is a monodentate ligand chosen from the group consisting of ReOH, wherein Re is a linear or branched Ci - Cs-alkyl moiety; cyclooctene, cycloheptene, cyclohexene, norbornene and ethene and n is 2 is used.

[0095] Preferred catalysts are those wherein X is halide (such as Cl; I; Br, F'), BF4; PFe', tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BArF4]'),(Ph)4B', CIOT, TfO' or SbFe'. TfO' stands for triflate (=trifluoromethanesulfonate).

[0096] More preferred catalysts are those wherein X is BF4; PFe', tetrakis[3,5-bis(trifluorome- thyl)phenyl]borate ([BArF4]'),(Ph)4B', CIOT, TfO' or SbFe'.

[0097] Therefore, the present invention also relates to a process of selective hydrogenation (H8), which is the selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3’”), (H4), (H5), (H5’), (H6) or (H7), wherein a catalyst of formula (I), wherein X is chosen from the group consisting of halide (such as Cl; I; Br, F'), BF4; PFe', tetrakis[3,5-bis(trifluorome- thyl)phenyl]borate ([BArF4]'), (Ph)4B' CIOT, TfO' and SbFe'.

[0098] Therefore, the present invention also relates to a process of selective hydrogenation (H8’), which is the process of selective hydrogenation (H), (H1), (H2), (H2’), (H3), (H3’), (H3”), (H3’”), (H4), (H5), (H5’), (H6) or (H7), wherein a catalyst of formula (I), wherein X is chosen from the group consisting of

[0099] BF4’, PFe', tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BArF4]'), (Ph)4B' CIOT, TfO' and SbF6'.

[0100] The catalysts, which are used in the hydrogenation according to the present invention are made as disclosed in the prior art.

[0101] The hydrogenation according to the present invention can be carried without any solvent.

[0102] Therefore, the present invention also relates to a process of selective hydrogenation (H9), which is the 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 any solvent.

[0103] The hydrogenation according to the present invention can be carried out in the presence of at least one inert solvent.

[0104] The hydrogenation can be carried out in a solvent (or mixture of solvents). Suitable solvents are alkanes, esters, carbonates, lactones, ethers, amides, hydrocarbons, halogenated hydrocarbons, water and alcohols. Preferred solvents are water, hexane, CH2CI2, toluene, ethyl acetate, THF (=tetrahydrofuran), 2-Me-THF (=2-methyl-tetrahydrofuran), cyclopentyl methyl ether (=CPME), methanol, ethanol and isopropanol, especially preferred solvents are methanol, water and hexane.

[0105] Therefore, the present invention also relates to a process of selective hydrogenation (H10), which is the 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.

[0106] Therefore, the present invention also relates to a process of selective hydrogenation (H10’), which is the process of selective hydrogenation (H10), wherein the solvent is chosen from the group consisting of alkanes, esters, carbonates, lactones, ethers, amides, hydrocarbons, halogenated hydrocarbons, water and alcohols.

[0107] Therefore, the present invention also relates to a process of selective hydrogenation (H10”), which is the process of selective hydrogenation (H10), wherein the solvent is chosen from the group consisting of water, hexane, CH2CI2, toluene, ethyl acetate, THF, 2-Me-THF, cyclopentyl methyl ether, methanol, ethanol and isopropanol.

[0108] Therefore, the present invention also relates to a process of selective hydrogenation (H10’”), which is the process of selective hydrogenation (H10), wherein the solvent is chosen from the group consisting of methanol, water and hexane.

[0109] The catalyst of formula (I) according to the present invention is usually used in an amount of 0.001 - 1 mol-% (preferably 0.001 - 0.5 mol-%) (based on the number of moles of the compounds of formula (III)).

[0110] Therefore, the present invention also relates to a process of selective hydrogenation (H11), which is the 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 - 1 mol-% (based on the number of moles of the compounds of formula (III)).

[0111] Therefore, the present invention also relates to a process of selective hydrogenation (H1 T), which is the 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 - 0.5 mol-% (based on the number of moles of the compounds of formula (III)).

[0112] The hydrogenation process can be carried out with (pure) H2 gas or with a gas, which comprises H2. Preferably, the hydrogenation process according to the present invention is carried out with (pure) H2 gas.

[0113] Therefore, the present invention also relates to a process of selective hydrogenation (H12), which is the 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 (H1 T), wherein the hydrogenation is carried out with (pure) H2 gas or with a gas, which comprises H2. Therefore, the present invention also relates to a process of selective hydrogenation (H12’), which is the 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 (H1 T), wherein the hydrogenation is carried out with H2 gas.

[0114] The hydrogenation process can be carried out at ambient pressure as well as at elevated pressure. Preferably, the hydrogenation process according to the present invention is carried out at a pressure of 1 - 50 bar, more preferably at 1 - 30 bar. Usually, the reaction is carried out in an autoclave (or any other vessel, which can resist the pressure).

[0115] Therefore, the present invention also relates to a process of selective hydrogenation (H13), which is the 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), (H1 T), (H12) or (H12’), wherein the hydrogenation is carried out at ambient pressure.

[0116] Therefore, the present invention also relates to a process of selective hydrogenation (H13’), which is the 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), (H1 T), (H12) or (H12’), wherein the hydrogenation is carried out at a pressure of 1 - 50 bar, preferably at 1 - 30 bar.

[0117] The hydrogenation is usually carried out at a temperature of -10 - 150 °C. (preferably 10 - 100 °C)

[0118] Therefore the present invention also relates to a process of selective hydrogenation (H14), which is the 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), (H1 T), (H12), (H12’), (H13) or (H 13’), wherein the hydrogenation is carried out at a temperature of -10 - 150 °C.

[0119] The following examples serve to illustrate the invention. The temperature is given in °C and all percentages are related to the weight. Examples

[0120] General catalyst synthesis (Example 1)

[0121] 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 a period of 30 min followed by the addition of HBF4 (125 pl (50 % in H2O)). Then the catalyst was participated with diethyl ether (40 mL), filtered off, washed with diethyl ether and dried afterwards.

[0122] All other used catalyst in the following examples have been produced in analogy to the process of example 1.

[0123] Hydrogenation Examples

[0124] Example 2: Hydrogenation reactions

[0125] 440 mmol Dehydroisophytol (compound of formula (I I lb);=DI P), 650 ml methanol and 4,4 mmol of the [Rh(cyc-Japhos)(NBD)]BF4, which was produced as disclosed in example 1 , were put into an autoclave. The mixture was stirred and the H2 was added in form of H2 gas. The autoclave was thermostated to 25° C and hydrogen pressure released after the desired reaction time. Analysis of the reaction mixture resulted in Table 1 (No 1).

[0126] The following examples have been made in analogy to the process of example 2 (the tables

[0127] 1-3 list the difference to the reaction conditions) dehydroisophytol; = 3,7,11 ,15-tetramethylhexadecan-3-ol.

[0128] phytol; = 3,7,11 ,15-tetramethylhexadecan-3-ol.

[0129] Tab e 3. *DIP=Dehydroisophytol; IP= isophytol; DilP=perhydrogenated dehydroisophytol;

[0130] = 3,7,11 ,15-tetramethylhexadecan-3-ol.

Claims

Claims1. A process of selective hydrogenation comprising the step of selectively hydrogenating alkynes to alkenes in the presence of at least one catalyst of formula (I)[M+(L1)(L2)n]X (I), whereinM is Rh or Ir, andL1 is a bidentate phosphine ligand of formula (II) (R)2-P-A-P-(R1)2(II), whereinR is a substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl or isopropyl, andR1is s substituted or unsubstituted cyclohexyl, substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted anthracenyl, anisyl, tert-butyl or isopropyl,A is a bridging moiety chosen from the group consisting of ■■■(CH2)m---werein m is an integer of value 1 - 6; andwherein z is 0 or 1 , andL2 is a bidentate ligand or a monodentate ligand, with the proviso that when L2 is a bidentate ligand, then n is 1 and L2 is not a bidentate ligand of formula(II) when L2 is a monodentate ligand, then n is 2, andX is an anion; and wherein any dotted line in formulae represents the bond by which the substituent is bound to the rest of the molecule.

2. The process according to claim 1 , wherein a starting material comprising a carboncarbon triple bond is hydrogenated selectively.

3. The process according to claim 1 or claim 2, wherein a compound of formula (III)R5R4C=C - C - R3(Hl)R2whereinR2is a linear or branched Ci-Css-alkyl; or a linear or branched C2-C35-alkenyl moiety, wherein the C chain can be substituted, andR3is H; a linear or branched Ci-C4-alkyl, wherein the C chain can be substituted, andR4is H; s cyclic, linear or branched Ci-Ce-alkyl, wherein the C chain can be substituted; or a Cs- Ci2-cyclic aromatic moiety, which can be substituted, andR5is H or OH or a OCi-C4-alkyl or a O(CO)Ci-C4-alkyl, is hydrogenated selectively to a compound of the formula (IV)4. The process according to any of the preceding claims, wherein a compound of formula (III)R5R4C=C - C - R3(Hl)R2whereinR2is a linear or branched Ci-C2o-alkyl; or a linear or branched C2-C2o-alkenyl moiety, wherein the C chain can be substituted, andR3is a Ci-C2-alkyl, andR4is H, andR5is OH or a O(CO)Ci-C2-alkyl, is hydrogenated selectively to a compound of the formula (IV)5. The process according to any of the preceding claims, wherein a catalyst of formula (I), wherein M is Rh is used.

6. The process according to any of the preceding claims, wherein a catalyst of formula (I), whereinL1 is a bidentate phosphine ligand chosen from the group consisting of the ligands of formula (Ila) to (lip)7. The process according to any of the preceding claims, wherein a catalyst of formula (I), wherein L2 is a bidentate ligand chosen from the group consisting of cyclohexadiene, cycloheptadiene 1 ,5-cyclooctadiene (COD) and norbornadiene (NBD), and n is 1 is used.

8. The process according to any of the preceding claims 1 - 6, wherein a catalyst of formula (I), wherein L2 is a monodentate ligand chosen from the group consisting of ReOH, wherein Re is a linear or branched Ci - Cs-alkyl moiety; cyclooctene, cycloheptene, cyclohexene, norbornene and ethene and n is 2 is used.

9. The process according to any of the preceding claims, wherein a catalyst of formula (I), wherein X is chosen from the group consisting of halide (such as Cl; I; Br, F’), BF4 , PFe’, tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ([BArF4]'), (Ph)4B; CIOT, TfO’ and SbFe'.

10. The process according to any of the preceding claims, wherein the hydrogenation is carried out without any solvent.

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

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

13. The process according to any of the preceding claims, wherein the hydrogenation is carried out with (pure) H2 gas or with a gas, which comprises H2.

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

15. The process according to any of the preceding claims, wherein the hydrogenation is carried out carried at a temperature of -10 - 150 °C.

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

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