Elimination Reactions of (<i>E</i>)-2,4-Dinitrobenzaldehyde <i>O</i>-Benzoyloximes Promoted by R<sub>2</sub>NH/R<sub>2</sub>NH<sub>2</sub><sup>+</sup> in 70 mol % MeCN(aq). Change of Reaction Mechanism
作者:Sang Yong Pyun、Bong Rae Cho
DOI:10.1021/jo8019412
日期:2008.12.5
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.