NEW METHOD FOR DETERMINATION OF HYDROGEN ABSTRACTION ABILITY OF ORGANIC PEROXIDES

The hydrogen abstraction ability of dialkyl peroxides was determined i n the presence of 2.0 M 2,4-diphenyl-4-methyl-1-pentene (alpha-methyls tyrene dimer, MSD) in cyclohexane at 140 degrees C. Cyclohexyl radical s produced through hydrogen abstraction by peroxide-derived radicals a re efficiently trapped by MSD. Trapping yields were greatly dependent on individual peroxides, decreasing in the following order: di-t-butyl peroxide (72%) > dicumyl peroxide (54%)> di-t-amyl peroxide (22%) > d i-t-hexyl peroxide (14%). In this case, the main hydrogen abstracting radicals were alkoxy radicals produced from the peroxides. The hydroge n abstraction ability of dialkyl peroxides was also tested in neat cyc lohexane. The dehydrodimer yields of cyclohexane were almost the same (40-50%) and close to theoretical values. This clearly demonstrates th at alkyl as well as alkoxy radicals act as effective hydrogen abstract ors in the absence of MSD. MSD trapping is useful for providing inform ation on hydrogen abstraction ability of organic peroxides in the pres ence of styrenic monomers.