NUCLEOPHILIC-SUBSTITUTION REACTIONS OF PHENYL CHLOROFORMATES

被引：86
作者：
YEW, KH
KOH, HJ
LEE, HW
LEE, I
机构：
[1] Department of Chemistry, Inha University, Inchon
来源：
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2 | 1995年 / 12期
关键词：
D O I：
10.1039/p29950002263
中图分类号：
O62 [有机化学];
学科分类号：
070303 ; 081704 ;
摘要：
Methanolysis and aminolysis of phenyl chloroformates in acetonitrile have been investigated. The rates are slow due to initial-state stabilization by strong resonance electron donation form the phenoxy group. In both reactions the large positive values of rho(Y) = 0.8-1.6 and low Delta H-double dagger and Delta S double dagger values show that the transition state is strongly associative with little bond breaking. This mechanism is supported by the relatively large solvent isotope effect, k(MeOH)/k(MeOD) congruent to 2.3-2.5, and by the relatively strong inverse secondary kinetic isotope effect, k(H)/k(D) congruent to 0.74-0.94, involving deuteriated aniline nucleophiles, in addition to a negative value of rho(XY). The dependence of aniline basicity, beta(X)(beta(nuc)) congruent to 0.8, and the rho(X) values of -2.3 are similar to those corresponding values for the reactions of benzoyl chlorides which have been predicted to react by an associative S(N)2 mechanism. These observations are consistent with a concerted displacement mechanism for the methanolysis and aminolysis of phenyl chloroformates.
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页码：2263 / 2268
页数：6
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