A kinetic study of the substituent effect on the reactivity of 4-(p-substituted phenyl)-4-oxo-2- bromobutanoic acids in the solvolytic elimination in MeZSO was carried out. It was found that electron-withdrawing groups increased the rate of reaction and electron-donating groups decreased the rate. Hammett correlation of this substituent effect was obtained with u values in Me&30-& at 36 and 60 OC. The p observed value, the isotopic effect, and the leaving ...