Reaktivit�t und Selektivit�t bei der Oxidation von Styrolderivaten. IV. Untersuchungen zur Oxidation von substituierten ?,?-Dimethylstyrolen
作者:W. Y. Suprun
DOI:10.1002/prac.19983400308
日期:——
The liquid phase oxidation of substituted (p-MeO-, p-Cl-, m-CF3-) 2-aryl-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 oxygen was investigated in chlorobenzene solution and in presence of cumene and of cumene hydroperoxide in the temperature range 65-125 degrees C. The product yields were determined gaschromatographically. The differences of the activation energies of epoxide formation and the parallel reactions were calculated. They amount to 19-48 kJ/mol. The epoxide selectivity increases with increasing temperature and increasing concentration 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.