Elimination reactions of (E)-2,4-dinitrobenzaldehyde O-benzoyloximes promoted by R2NH/R2NH2(+) in 70 mol % MeCN(aq). Change of reaction mechanism.
Elimination reactions of (E)-2,4-(NO(2))(2)C(6)H(3)CHNOC(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 |beta(lg)| = 0.28-0.32. The result can be described by a negligible p(xy) interaction coefficient, p(xy) = partial differential beta/partial differential pK(lg) = partial differential beta(lg)/partial differential pK(BH) approximately = 0, which describes the interaction between the base catalyst and the leaving group. The negligible p(xy) coefficients are consistent with the (E1cb)(irr) mechanism.
Pyun
Sang Yong
SY
Department of Chemistry, Pukyong National University, Pusan 608-737, Korea. sypyun@pknu.ac.kr
Cho
Bong Rae
BR