Homolytic aromatic substitution. Part XXXVI. Total and partial rate factors for the phenylation of some para-disubstituted derivatives of benzene

Abstract

Total and partial rate factors for the phenylation of some para-disubstituted derivatives of benzene have been obtained by means of competitive reactions in which benzoyl peroxide has been allowed to decompose in equimolar mixtures of the para-disubstituted derivative of benzene and para-dichlorobenzene. Nitrobenzene was also used as standard in a few cases. When both groups in a para-disubstituted benzene have similar electronic properties their effect on reactivity is additive compared with that of the two monosubstituted benzenes having the same groups. When the two groups have opposite electronic properties the reactivity is lowered below that of the more reactive of the corresponding two monosubstituted benzenes. Revised figures are reported for total and partial rate factors for some monosubstituted benzenes.