Method for producing dienes by hydrodimerization
View Patent ↗The invention relates to a process for preparing substituted or unsubstituted 1,7-diolefins by hydrodimerizing non-cyclic olefins having at least two conjugated double bonds in the presence of a reducing agent and of a catalyst, wherein the catalyst used is a metal-carbene complex.
1. A process for preparing a substituted or unsubstituted 1,7-diolefin, comprising:
hydrodimerizing a non-cyclic olefin having at least two conjugated double bonds in a presence of a reducing agent and a catalyst,
wherein the reducing agent comprises at least one selected from the group consisting of formic acid and a formate, the reducing agent is metered in during a course of the hydrodimerizing of the non-cyclic olefin such that a ratio of the non-cyclic olefin to the reducing agent is from 1:1 to 10:1, and the catalyst comprises a metal-carbene complex which has a metal of group 8 to 10 of the Periodic Table and at least one carbene ligand of the structure 2
where:
R 1 , R 2 =—(CH 2 ) n —B
B=mono- or polycyclic aryl group having 6 to 14 carbon atoms or mono- or polycyclic heterocycle having 5 to 14 carbon atoms and heteroatoms, where this heterocycle has 1 to 3 heteroatoms selected from the group consisting of N, O and S,
n=0-4 and
R 3 and R 4 =substituents selected from the group consisting of hydrogen, alkyl, heteroaryl, aryl, —CN, —COOH, —COO-alkyl, —COO-aryl, —OCO-alkyl, OCO-aryl, —OCOO-alkyl, OCOO-aryl, —CHO, —CO-alkyl, —CO-aryl, —NH 2 , —NH(alkyl), —N(alkyl) 2 , NH(aryl), —N(aryl) 2 , —F, —Cl, —Br, —I, —OH, —CF 3 , —NO 2 , -ferrocenyl, —SO 3 H, and —PO 3 H 2 , where the alkyl groups have 1 to 12 carbon atoms and the aryl groups 5 to 14 carbon atoms, and the substituents of R 3 and R 4 may also be part of a bridging aliphatic or aromatic ring,
and the substituents of R 1 and R 2 are the same or different and are substituted or unsubstituted, and the substituents of R 3 and R 4 are the same or different and are substituted or unsubstituted.
2. The process according to claim 1 ,
wherein the metal-carbene complex comprises at least one metal selected from the group consisting of nickel, rhodium, palladium and platinum.
3. The process according to claim 2 ,
wherein the metal-carbene complex has palladium as the metal.
4. The process according to claim 1 ,
wherein the metal-carbene complex comprises at least one carbene ligand of the structure 2 where R 3 and R 4 are each hydrogen.
5. The process according to claim 4 ,
wherein the metal-carbene complex comprises at least one carbene ligand of the structure 2 where R 3 and R 4 are each hydrogen and R 1 and R 2 , where n=0, and B are each a phenyl or 2,4,6-trimethylphenyl group.
6. The process according to claim 4 , wherein the at least one carbene ligand consists of a carbene ligand of the structure 2 which satisfies that R 3 and R 4 are each hydrogen and R 1 and R 2 , where n=0, and B are each a 2,4,6-trimethylphenyl group.
7. The process according to claim 4 , wherein the at least one carbene ligand consists of a carbene ligand of the structure 2 which satisfies that R 3 and R 4 are each hydrogen and R 1 and R 2 , where n=0, and B are each a phenyl group.
8. The process according to claim 1 ,
wherein the catalyst comprises 1 to 500 ppm by mass of a metal based on an overall mass of a reaction mixture, at a start of the hydrodimerizing.
9. The process according to claim 1 ,
wherein the non-cyclic olefins having at least two conjugated double bonds are compounds selected from the group consisting of 1,3-butadiene, isoprene, 1,3-pentadiene, chloroprene, and corresponding mixtures which comprise non-cyclic olefins with at least two conjugated double bonds.
10. The process according to claim 9 ,
wherein the non-cyclic olefin comprises 1,3-butadiene.
11. The process according to claim 1 ,
wherein non-cyclic olefins either have no stabilizer or have a stabilizer comprising one of alkylated phenols and stable N-oxyl radicals.
12. The process according to claim 11 ,
wherein the non-cyclic olefins comprise a free radical stabilizer comprising one of alkylated phenols and stable N-oxyl radicals.
13. The process according to claim 12 ,
wherein the N-oxyl radicals are selected from the group consisting of 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl and 2,2,6,6-tetramethylpiperidine N-oxyl.
14. The process according to claim 1 ,
wherein the reducing agent comprises formic acid and the formate.
15. The process according to claim 14 ,
wherein the reducing agent comprises formate.
16. The process according to claim 1 ,
wherein the reducing agent is formic acid.
17. The process according to claim 1 ,
wherein the reducing agent comprises at least one selected from the group consisting of ammonium formate, triethylammonium formate, trimethyl-ammonium formate, tripropylammonium formate, lithium formate, sodium formate, potassium formate, magnesium formate, and calcium formate.
18. The process according to claim 1 ,
wherein the hydrodimerizing of the non-cyclic olefins is performed in a presence of bases.
19. The process according to claim 18 ,
wherein the bases are selected from the group consisting of alkali metal hydroxides, alkali metal alkoxides and tertiary amines.
20. The process according to claim 1 , wherein the non-cyclic olefins comprise a free radical stabilizer comprising at least one stable N-oxyl radical.
21. The process according to claim 1 , wherein the catalyst comprises 1 to 50 ppm by mass of the metal based on the overall mass of the reaction mixture, at the start of the hydrodimerizing.
22. The process according to claim 21 , wherein the at least one carbene ligand consists of a carbene ligand of the structure 2 which satisfies that R 3 and R 4 are each hydrogen and R 1 and R 2 , where n=0, and B are each a 2,4,6-trimethylphenyl group.