The oxidation of secondary alcohols by dimethyldioxirane: re-examination of kinetic isotope effects

The kinetic isotope effects for the oxidation of a series of deuterated isopropanols and α-trideuteromethyl benzyl alcohol by dimethyldioxirane ( 1 ) to the corresponding ketones were determined in dried acetone at 23°C. A primary kinetic isotope effect (PKIE) of 5.2 for the oxidation of isopropyl-2-d alcohol by 1 was obtained. The SKIEs for oxidation of α-trideuteromethyl benzyl alcohol and isopropyl-1,1,1,3,3,3-d 6 alcohol were found to be 1.07 and 0.98, respectively. Oxidation of isopropanol-d by 1 yielded a k OH /k OD value of 1.12, which is similar to that previously reported for α-methylbenzyl alcohol-d. Both normal and inverse secondary kinetic isotope effect (SKIEs) are observed. Mechanistically, the results indicate that the process is more complex than the previously proposed models.