Process for making trans-isocarveol

摘要

A process for making trans-isocarveol, an intermediate useful in the manufacture of perillyl alcohol, is disclosed. The process comprises isomerizing a mixture comprising cis-limonene oxide (cis-LMO) and trans-limonene oxide (trans-LMO) in the presence of a phenolic modifier and a chromium catalyst. The process is performed at a temperature less than 220° C. to convert more than 50% of the cis-LMO to trans-isocarveol and less than 50% of the trans-LMO to cis-isocarveol. We surprisingly found that a mixture of cis- and trans-LMO can be selectively isomerized to produce mostly trans-isocarveol, which we discovered is the preferred isomer for making perillyl alcohol by direct isomerization.