Structure−Reactivity Correlations in the Aminolysis and Pyridinolysis of Bis(phenyl) and Bis(4-nitrophenyl) Thionocarbonates

Abstract

The reactions of a series of secondary alicyclic amines with bis(phenyl) and bis(4-nitrophenyl) thionocarbonates (BPTOC and BNPTOC, respectively), and a series of pyridines with the latter substrate, are subjected to a kinetic investigation in water, 25.0 °C, ionic strength 0.2 M (KCl). All the reactions obey pseudo-first-order kinetics under amine excess over the substrate. The reactions of piperidine with BPTOC are first order in amine, but those of the same substrate with the other secondary alicyclic amines exhibit a complex order, consistent with the existence of both a zwitterionic (T±) and an anionic (T-) tetrahedral intermediates on the reaction pathway. Deprotonation of T± by a secondary amine to give T- (rate coefficient k3) competes with expulsion of the amine moiety from T± (k-1), except in the reactions of 1-formylpiperazine whereby k-1 ≫ k3 [1-formylpiperazine], and a kinetics second order in amine is observed. The reactions of secondary alicyclic amines with BNPTOC are all first order in am...