Supercritical Alcoholysis of Bornyl Acetate in Fir Needle Essential Oil for Borneol Production

For the first time, a noncatalytic transesterification reaction (alcoholysis) of bornyl acetate in commercial fir needle essential oil (FNEO) is carried out using supercritical lower alcohols: methanol, ethanol, and isopropanol. Only the use of methanol is shown to ensure high conversion and selectivity of the reaction. For example, at 350°C after 1 h of the reaction in an autoclave reactor, 93% selectivity for borneol with 90% conversion of bornyl acetate is achieved. A further increase in the reaction time leads to a decrease in selectivity for borneol due to an unexpected increase in the concentration of camphor.