Process for preparing a mixture of terpene alcohols

Abstract

The present invention relates to a process for preparing a mixture of terpene alcohols comprising limonene-4-ol and terpinene-4-ol from terpinolene epoxide via an isomerization and/or hydrogenation reaction in the presence of a copper catalyst.

Claims

1. A process for preparing a mixture of terpene alcohols comprising limonene-4-ol of formula (II) ##STR00007## and terpinene-4-ol of formula (III) ##STR00008## said process comprising contacting terpinolene epoxide of formula (I) ##STR00009## with hydrogen in the presence of at least one copper catalyst and at least one inert organic solvent selected from carboxylic acid esters.

2. The process of claim 1, wherein the copper catalyst comprises copper chromite.

3. The process of claim 1, wherein the copper catalyst comprises at least one promoter selected from the group consisting of alkali metals, alkaline earth metals, manganese, bismuth, iron and combinations thereof.

4. The process of claim 3, wherein the promoter is selected from the group consisting of sodium, potassium, magnesium, calcium, barium, manganese, iron and combinations thereof.

5. The process of claim 1, wherein the copper catalyst comprises at least one binder or support material selected from the group consisting of aluminum oxide (Al.sub.2O.sub.3), silicon dioxide (SiO.sub.2), titanium dioxide (TiO.sub.2), zirconium dioxide (ZrO.sub.2), sodium silicate, calcium silicate, magnesium silicate, graphite, clay, zeolite, molecular sieves, and mixtures thereof.

6. The process of claim 1, wherein the carboxylic acid ester is selected from esters of the general formula R.sup.1COOR.sup.2 wherein R.sup.1 is hydrogen or a group selected from C.sub.1-C.sub.4-alkyl, C.sub.3-C.sub.6-cycloalkyl, C.sub.6-C.sub.10-aryl and C.sub.6-C.sub.10-aryl-C.sub.1-C.sub.4-alkyl and R.sup.2 is a group selected from C.sub.1-C.sub.4-alkyl, C.sub.3-C.sub.6-cycloalkyl, C.sub.6-C.sub.10-aryl and C.sub.6-C.sub.10-aryl-C.sub.1-C.sub.4-alkyl, each of the aforementioned groups optionally being substituted with one or more substituents selected from C.sub.1-C.sub.4-alkoxy.

7. The process of claim 1, wherein the carboxylic acid ester is selected from C.sub.1-C.sub.4-alkyl acetates.

8. The process of claim 1, wherein the carboxylic acid ester is ethyl acetate.

9. The process of claim 1, wherein the temperature is from 100 to 200 C.

10. The process of claim 1, wherein the hydrogen pressure is from 2 to 10 bar.

11. The process of claim 1, wherein said mixture is subjected to subsequent hydrogenation to give terpinene-4-ol of formula (III).

12. The process of claim 11, wherein the hydrogenation is carried out in the presence of at least one nickel-containing catalyst.

13. The process of claim 12, wherein the nickel-containing catalyst is Raney nickel.

14. The process of claim 1, wherein terpinolene epoxide of formula (I) is prepared by epoxidation of terpinolene of the formula (IV) ##STR00010##

15. The process of claim 1, wherein said mixture or terpinene-4-ol of the formula (III) is further converted into ()-2-exo-(2-Methylbenzyloxy)-1-methyl-4-isopropyl-7-oxabicyclo[2.2.1]heptane, any of its individual enantiomers or any non-racemic mixture thereof.

Description

EXAMPLE 1

(1) Isomerization/Hydrogenation with Copper Chromite Catalyst, Barium Promoted (Product No. AB120210, CAS No. 12018-10-9, from ABCR GmbH, Karlsruhe, Germany) in Ethyl Acetate (125 C., 25% Terpinolene Epoxide in Ethyl Acetate)

(2) 16 g (0.102 mol) terpinolene epoxide (97.1%), 48 g (0.545 mol) ethyl acetate and 0.918 g (0.004 mol) copper chromite (CuCr.sub.2O.sub.4, barium promoted, Product No. AB120210, CAS no. 12018-10-9, from ABCR GmbH, Karlsruhe, Germany) were charged into an autoclave under nitrogen atmosphere. The mixture was pressurized with 5 bar H.sub.2 and then heated to 125 C. under vigorous stirring. The mixture was stirred for 40 h at 125 C. and then cooled to 25 C. The pressure was released and the catalyst was filtered off through a layer of diatomaceous earth. The remaining catalyst was washed with ethyl acetate (5 g). Filtrate and wash ethyl acetate were combined and ethyl acetate was distilled off at reduced pressure (distillation residue: 16.1 g). Quantitative gas chromatography (GC) (GC with internal standard) of the distillation residue showed a limonene-4-ol concentration of 48.11% and a terpinene-4-ol concentration of 34.65%. This corresponds to a yield of 49.8% for limonene-4-ol and 35.4% for terpinene-4-ol. Total yield of limonene-4-ol and terpinen-4-ol was 85.2%.

EXAMPLE 2

(3) Isomerization/Hydrogenation with Copper Chromite Catalyst, Barium Promoted (Product No. AB120210, CAS No. 12018-10-9, from ABCR GmbH, Karlsruhe, Germany) in Ethyl Acetate (125 C., 50% Terpinolene Epoxide in Ethyl Acetate)

(4) 32 g (0.204 mol) terpinolene epoxide (97.1%), 32 g (0.363 mol) ethyl acetate and 0.918 g (0.004 mol) copper chromite (CuCr.sub.2O.sub.4, barium promoted, Product No. AB120210, CAS no. 12018-10-9, from ABCR GmbH, Karlsruhe, Germany) were charged into an autoclave under nitrogen atmosphere. The mixture was pressurized with 5 bar H.sub.2 and then heated to 125 C. under vigorous stirring. The mixture was stirred for 24 h at 125 C. and then cooled to 25 C. The pressure was released and the catalyst was filtered off through a layer of diatomaceous earth. The remaining catalyst was washed with ethyl acetate (5 g). Filtrate and wash ethyl acetate were combined and ethyl acetate was distilled off at reduced pressure (distillation residue: 30.7 g). Quantitative GC (GC with internal standard) of the distillation residue showed a limonene-4-ol concentration of 75.33% and a terpinene-4-ol concentration of 8.51%. This corresponds to a yield of 74.4% for limonene-4-ol and 8.3% for terpinene-4-ol. Total yield of limonene-4-ol and terpinene-4-ol was 82.7%.

EXAMPLE 3

(5) Isomerization/Hydrogenation with Copper Chromite Catalyst, Containing Graphite (E 403 T from BASF) in Ethyl Acetate (140 C., 25% Terpinolene Epoxide in Ethyl Acetate)

(6) 16 g (0.100 mol) terpinolene epoxide (95.1%), 48 g (0.545 mol) ethyl acetate and 0.970 g (0.0042 mol) copper chromite (CuCr.sub.2O.sub.4, containing graphite, E 403 T from BASF) were charged into an autoclave under nitrogen atmosphere. The mixture was pressurized with 5 bar H.sub.2 and then heated to 140 C. under vigorous stirring. The mixture was stirred for 24 h at 140 C. and then cooled to 25 C. The pressure was released and the catalyst was filtered off through a layer of diatomaceous earth. The remaining catalyst was washed with ethyl acetate (5 g). Filtrate and wash ethyl acetate were combined and ethyl acetate was distilled off at reduced pressure (distillation residue: 15.8 g). Quantitative GC (GC with internal standard) of the distillation residue showed a limonene-4-ol concentration of 76.68% and a terpinene-4-ol concentration of 1.89%. This corresponds to a yield of 79.6% for limonene-4-ol and 1.9% for terpinene-4-ol. Total yield of limonene-4-ol and terpinene-4-ol was 81.5%.

EXAMPLE 4

(7) Isomerization/Hydrogenation with Copper Chromite Catalyst, Containing Barium (E 108 P from BASF) in Ethyl Acetate (140 C., 50% Terpinolene Epoxide in Ethyl Acetate)

(8) 32 g (0.2085 mol) terpinolene epoxide (99.1%), 32 g (0.363 mol) ethyl acetate and 1.94 g (0.0084 mol) copper chromite (CuCr.sub.2O.sub.4, containing barium, E 108 P from BASF) were charged into an autoclave under nitrogen atmosphere. The mixture was pressurized with 5 bar H.sub.2 and then heated to 140 C. under vigorous stirring. The mixture was stirred for 30 h at 140 C. and then cooled to 25 C. The pressure was released and the catalyst was filtered off through a layer of diatomaceous earth. The remaining catalyst was washed with ethyl acetate (5 g). Filtrate and wash ethyl acetate were combined and ethyl acetate was distilled off at reduced pressure (distillation residue: 31.8 g). Quantitative GC (GC with internal standard) of the distillation residue showed a limonene-4-ol concentration of 59.22% and a terpinene-4-ol concentration of 21.04%. This corresponds to a yield of 59.4% for limonene-4-ol and 20.8% for terpinene-4-ol. Total yield of limonene-4-ol and terpinene-4-ol was 80.2%.

EXAMPLE 5

(9) Isomerization/Hydrogenation with Copper Chromite Catalyst, Containing Manganese (Cu 1955 P from BASF) in Ethyl Acetate (125 C., 25% Terpinolene Epoxide in Ethyl Acetate)

(10) 16 g (0.104 mol) terpinolene epoxide (99.1%), 48 g (0.545 mol) ethyl acetate and 0,970 g (0.0042 mol) copper chromite (CuCr.sub.2O.sub.4, containing manganese, Cu 1955 P from BASF) were charged into an autoclave under nitrogen atmosphere. The mixture was pressurized with 5 bar H.sub.2 and then heated to 125 C. under vigorous stirring. The mixture was stirred for 24 h at 125 C. and then cooled to 25 C. The pressure was released and the catalyst was filtered off through a layer of diatomaceous earth. The remaining catalyst was washed with ethyl acetate (5 g). Filtrate and wash ethyl acetate were combined and ethyl acetate was distilled off at reduced pressure (distillation residue: 15.1 g). Quantitative GC (GC with internal standard) of the distillation residue showed a limonene-4-ol concentration of 69.6% and a terpinene-4-ol concentration of 14.22%. This corresponds to a yield of 66.3% for limonene-4-ol and 13.4% for terpinene-4-ol. Total yield of limonene-4-ol and terpinene-4-ol was 79.7%.

COMPARATIVE EXAMPLES

Comparative Example 1

(11) Isomerization/Hydrogenation with Copper Chromite Catalyst, Barium Promoted (Product No. AB120210, CAS No. 12018-10-9, from ABCR GmbH, Karlsruhe, Germany) in Ethanol (125 C., 25% Terpinolene Epoxide in Ethanol)

(12) 40 g (0.2504 mol) terpinolene epoxide (95.2%), 120 g (2.609 mol) ethanol and 1.14 g (0.005 mol) copper chromite (CuCr.sub.2O.sub.4, barium promoted, from ABCR GmbH, Karlsruhe, Germany) were charged into an autoclave under nitrogen atmosphere. The mixture was pressurized with 5 bar H.sub.2 and then heated to 125 C. under vigorous stirring. The mixture was stirred for 27 h at 125 C. and then cooled to 25 C. The pressure was released and the catalyst was filtered off through a layer of diatomaceous earth. The remaining catalyst was washed with ethanol (12.5 g). Filtrate and wash ethyl acetate were combined and ethyl acetate was distilled off at reduced pressure (distillation residue: 39.2 g). Quantitative GC (GC with internal standard) of the distillation residue showed a limonene-4-ol concentration of 67.7% and a terpinene-4-ol concentration of 4.43%. This corresponds to a yield of 69.7% for limonene-4-ol and 4.5% for terpinene-4-ol. Total yield of limonene-4-ol and terpinene-4-ol was 74.2%.

Comparative Example 2

(13) Isomerization/Hydrogenation with Copper Chromite Catalyst, Barium Promoted (Product No. AB120210, CAS No. 12018-10-9, from ABCR GmbH, Karlsruhe, Germany) in Ethanol (125 C., 25% Terpinolene Epoxide in Ethanol)

(14) 40 g (0.2472 mol) terpinolene epoxide (94.0%), 120 g (2.609 mol) ethanol and 1.14 g (0.005 mol) copper chromite (CuCr.sub.2O.sub.4, barium promoted, from ABCR GmbH, Karlsruhe, Germany) were charged into an autoclave under nitrogen atmosphere. The mixture was pressurized with 5 bar H.sub.2 and then heated to 125 C. under vigorous stirring. The mixture was stirred for 45 h at 125 C. and then cooled to 25 C. The pressure was released and the catalyst was filtered off through a layer of diatomaceous earth. The remaining catalyst was washed with ethanol (12.5 g). Filtrate and wash ethyl acetate were combined and ethyl acetate was distilled off at reduced pressure (distillation residue: 36.4 g). Quantitative GC (GC with internal standard) of the distillation residue showed a limonene-4-ol concentration of 44.7% and a terpinene-4-ol concentration of 33.0%. This corresponds to a yield of 42.8% for limonene-4-ol and 31.2% for terpinene-4-ol. Total yield of limonene-4-ol and terpinene-4-ol was 74.0%.