SECONDARY DEUTERIUM ISOTOPE EFFECTS IN RADICAL-FORMING REACTIONS .3. DECOMPSOITION OF ACETYL PEROXIDE

The α-deuterium secondary kinetic isotope effect on the decarboxylation of the acetoxy radical has been estimated from the ratio of yields of the two isomeric trideuterated methyl acetates formed from decomposition of unsymmetrically trideuterated acetyl peroxide. The estimated isotope effect is 1.09 ± 0.02 for three deuterium atoms. The isotope effects on the overall decomposition rates have been measured by a new double-labeling technique. These isotope effects are small and appear to be sensitive to changes in temperature and solvent viscosity. They are interpreted in terms of a mechanism in which diffusive separation of the acetoxy-acetoxy radical pair is included. © 1969, American Chemical Society. All rights reserved.