Aminolysis of Aryl Chlorothionoformates with Anilines in Acetonitrile: Effects of Amine Nature and Solvent on the Mechanism
作者:Hyuck Keun Oh、Joo Suk Ha、Dae Dong Sung、Ikchoon Lee
DOI:10.1021/jo0487247
日期:2004.11.1
chloroformates (1−4) in water, for which rate-limiting formation of a tetrahedral intermediate, T±, is predicted. On the basis of the large negative cross-interaction constant, ρXY = −0.77, failure of the reactivity−selectivity principle, normal kH/kD values involving deuterated nucleophiles (XC6H4ND2), and low ΔH≠ with large negative ΔS≠ values, a concerted mechanism with a four-membered hydrogen bonded cyclic
在5.0°C的条件下,研究了芳基氯硫代甲酸酯(7,YC 6 H 4 OC(S)Cl)与苯胺(XC 6 H 4 NH 2)在乙腈中的氨解作用。该速率比芳基氯甲酸酯(6,YC 6 H 4 OC(O)Cl)的相应反应的速率慢。此速率序列是,对氯甲酸烷基酯(反向1 - 4)在水中,为此,速率限制形成四面体中间体,T的±,进行了预测。基于较大的负交叉相互作用常数ρXY= -0.77,反应性-选择性原理失败,涉及氘化亲核试剂(XC 6 H 4 ND 2)的正常k H / k D值,并且低ΔH ≠与大的负Δ小号≠对于标题反应系列,提出了具有四元氢键的环状过渡态(11)的协同机理。已经显示出,对于6和7的氨解,溶剂从水变为乙腈引起从逐步到一致的机械变化。