Nucleophilic Substitution Reactions of Aryl Dithioacetates with Pyridines in Acetonitrile
作者:Hyuck Keun Oh、Myoung Hwa Ku、Hai Whang Lee、Ikchoon Lee
DOI:10.1021/jo025637a
日期:2002.5.1
are carried out in acetonitrile at 60.0 degrees C. A biphasic Brönsted plot is obtained with a change in slope from a large value (beta(X) congruent with 0.9) to a small value (beta(X) congruent with 0.4) at pK(a) degrees = 5.2, which is attributed to a change in the rate-limiting step from breakdown to formation of a zwitterionic tetrahedral intermediate, T(+/-), in the reaction path as the basicity
芳基二硫代乙酸酯(CH(3)C(= S)SC(6)H(4)Z)的吡啶分解反应(XC(5)H(4)N)的动力学研究在60.0摄氏度的乙腈中进行。在pK(a)度= 5.2时,斜率从大值(β(X)等于0.9)变小值(β(X)等于0.4)获得斜率双相图。随着吡啶亲核试剂的碱度增加,反应路径中的限速步骤从分解到两性离子四面体中间体T(+/-)的变化。交叉相互作用常数rho(XZ)从大的正值(rho(XZ)= +1.34)到小的负值(rho(XZ)= -0.15)的清晰变化可以支持所提出的机械变化。