Mononuclear Heterocyclic Rearrangements. Part 16. Kinetic Study of the Rearrangement of Some ortho-Substituted Z-Phenylhydrazones of 3-Benzoyl-5-phenyl-1,2,4-oxadiazole into 2-Aryl-4-benzoylamino-5-phenyl-1,2,3-triazoles in Dioxane-Water and in Benze

摘要

the effects of six ortho-substituents (Me, Et, F, Cl, Br and NO_2), showing different electronic and proximity effects, on the rate of the title reaction have been studied at 313.15 K in dioxane/water at various pS~+ values (3.8-12.7) and in benzene at various piperidine concentrations. The kinetic data obtained have been treated by using a Fujita-Nishioka approach with a dissection of the ortho-substituent effect in 'ordinary polar effect', 'proximity polar effect' and 'primary steric effect'. The different contributions calculated have been discussed in the framework of the various mechanisms proposed for the studied rearrangement.