REACTIVITY AND SELECTIVITY IN THE OXIDATI ON OF STYRENE DERIVATIVES -IV - STUDIES ON THE OXIDATION OF SUBSTITUTED BETA-BETA-DIMETHYLSTYRENES

The liquid phase oxidation of substituted (p-MeO-, p-Cl-, m-CF3-) 2-ar yl-3-methyl-but-2-enes, of 1,1-diphenyl-2-methyl-propene, of 1-ethoxy- 2-methyl-1-phenyl-propene and of 9-isopropylidene-fluorene with pure o xygen was investigated in chlorobenzene solution and in presence of cu mene and of cumene hydroperoxide in the temperature range 65-125 degre es C. The product yields were determined gaschromatographically. The d ifferences of the activation energies of epoxide formation and the par allel reactions were calculated. They amount to 19-48 kJ/mol. The epox ide selectivity increases with increasing temperature and increasing c oncentration of olefin. The relative chain propagation constants (k(pC =C)) were determined by competitive oxidation with cumene. The k(pC=C) values of substituted beta,beta-dimethylstyrenes can be correlated by a LFE-relationship with the ionisation energies of the olefins.