Kinetics and mechanism of the aminolysis ofO-ethylS-aryl thiocarbonates in acetonitrile
作者:Hyuk Keun Oh、Yun Ho Lee、Ikchoon Lee
DOI:10.1002/(sici)1097-4601(2000)32:3<131::aid-kin2>3.0.co;2-c
日期:——
The aminolysis of O-methyl S-aryl thiocarbonates with benzylamines are studied in acetonitrile at −45.0 C. The βX (βnuc) values are in the range 0.62-0.80 with a negative cross-interaction constant, ρXZ = −0.42, which are interpreted to indicate a concerted mechanism. The kinetic isotope effects involving deuterated benzylamine nucleophiles (XC6H4CH2ND2) are large, kH/kD = 1.29-1.75, suggesting that
在 -45.0 C 的乙腈中研究了 O-甲基 S-芳基硫代碳酸酯与苄胺的氨解作用。βX (βnuc) 值在 0.62-0.80 范围内,具有负交叉相互作用常数 ρXZ = -0.42,可解释为表明一个协调的机制。涉及氘代苄胺亲核试剂 (XC6H4CH2ND2) 的动力学同位素效应较大,kH/kD = 1.29-1.75,表明 NH(D) 键在过渡态通过形成氢键四中心环状结构而部分断裂。MeO 基团提供的强大推动力增强了协同机制,这增强了假定的两性离子四面体中间体中苄胺和烯硫醇盐的离核性。