Kinetics of the epoxidation of geraniol and model systems by dimethyldioxirane

Abstract

The mono-epoxidation of geraniol by dimethyldioxirane was carried out in various solvents. In all cases, the product ratios for the 2,3 and 6,7 mono-epoxides were in agreement with literature values. Kinetic studies were carried out at 23 °C in the following dried solvent systems: acetone (k 2 = 1.49 M-1s-1), carbon tetrachloride/acetone (9/1, k2=2.19 M-1s-1), and methanol/acetone (9/1, k2 = 17 M-1s-1). Individual k2 values were calculated for epoxidation of the 2,3 and 6,7 positions in geraniol. The non-conjugated diene system was modeled employing two simple independent alkenes: 2-methyl-2-pentene and 3-methyl-2-buten-1-ol by determining the respective k2 values for epoxidation in various solvents. The kinetic results for each independent alkene showed that the relative reactivity of the two epoxidation sites in geraniol as a function of solvent was not simply a summation of the independent alkene systems.