Elimination Reactions of (E)-2,4-Dinitrobenzaldehyde O-Benzoyloximes Promoted by R(2)NH/R(2)NH(2)(+) in 70 mol % MeCN(aq). Change of Reaction Mechanism

Abstract

Elimination reactions of(E)-2,4-(NO(2))(2)C(6)H(3)CH=NOC(O)-C(6)H(4)X (1) promoted by R(2)NH/R(2)NH(2)(+) in 70 mol % MeCN(aq) have been studied kinetically. The reactions are second-order and exhibit Bronsted beta = 0.27-0.32 and vertical bar beta lg vertical bar 0.28-0.32. The result can be described by a negligible interaction coefficient, p(xy) = partial derivative beta/partial derivative pk(lg) = partial derivative beta(lg)/partial derivative pk(BH) approximate to 0, which describes the interaction between the base catalyst and the leaving group. The negligible p(xy) coefficients are consistent with the (Elcb)(irr) mechanism.