Base-catalysed aromatic nucleophilic substitution reactions of O-aryl oximes with pyrrolidine in non-polar aprotic, dipolar aprotic, and protic solvents

Abstract

The kinetics of O-(2,4-dinitrophenyl) substituted cyclohexanone oxime and benzophenone oxime with pyrrolidine, a secondary alkyl amine have been studied in chlorobenzene, MeCN, DMF, DMSO, and methanol. The reactions are second order in amine in all the solvents except chlorobenzene, in which the order is more than two. Observed rate constants decrease with an increase in temperature in all aprotic solvents except protic methanol, in which an increase in rate constant is observed. The results are explained on the basis of base-catalysed collapse of the tetrahedral intermediate by homo- and hetero-conjugated acids.