Process for making terpene esters
View Patent ↗A process for making terpene esters is disclosed. Reaction of a terpene alcohol with acetic anhydride in the presence of a high-boiling amine provides a terpene ester. Acetic acid, which is distilled from the reaction mixture as it forms can be recovered. The terpene ester is distilled from the high-boiling amine to provide a product that is substantially free of nitrogen-containing impurities. The reaction mixture can be reused for subsequent acylations. The simple, economical process gives high-quality terpene esters while avoiding waste-disposal issues of other common acylation procedures.
1. A process which comprises reacting a terpene alcohol with acetic anhydride in the presence of a C 18 -C 40 aliphatic tertiary high-boiling amine to produce a reaction mixture comprising a terpene ester, distilling acetic acid from the reaction mixture as it forms, and isolating a purified terpene ester from the high-boiling amine by distillation, wherein the purified terpene ester is substantially free of nitrogen-containing impurities.
2. The process of claim 1 wherein the terpene alcohol is selected from the group consisting of linalool, geraniol, citronellol, nerol, α-terpineol, borneol, terpinen-4-ol, limonen-4-ol, carveol, lavandulol, menthol, 8-p-cymenol, pinanol, dihydromyrcenol, myrcenol, and mixtures thereof.
3. The process of claim 1 wherein the terpene alcohol is a tertiary, unsaturated terpene alcohol.
4. The process of claim 1 wherein the terpene alcohol is linalool.
5. The process of claim 1 wherein the high-boiling amine is tri-n-octylamine.
6. The process of claim 1 wherein the reaction is performed at a temperature within the range of 30° C. to 180° C.
7. The process of claim 1 wherein the reaction is performed in the presence of a dialkylaminopyridine catalyst.
8. The process of claim 1 wherein a distillation residue that contains the high-boiling amine is reused with fresh terpene alcohol and acetic anhydride to produce more terpene ester.
9. A process which comprises reacting linalool with acetic anhydride in the presence of a C 18 -C 40 aliphatic tertiary high-boiling amine at a temperature in the range of 60° C. to 180° C. to produce a reaction mixture comprising linalyl acetate, distilling acetic acid from the reaction mixture as it forms at or below atmospheric pressure, and isolating purified linalyl acetate from the high-boiling amine by vacuum distillation, wherein the resulting purified linalyl acetate is substantially free of nitrogen-containing impurities.
10. The process of claim 9 wherein the reaction is performed in the presence of 4-(dimethylamino)pyridine.
11. The process of claim 9 wherein the linalool is added to a heated mixture of acetic anhydride and the high-boiling amine.
12. The process of claim 9 wherein the high-boiling amine is tri-n-octylamine.