Perchlorate esters. 4. Kinetics and mechanism of the reactions of alkyl perchlorates with N,N-dimethylanilines in benzene
作者:Dennis N. Kevill、Betty W. Shen
DOI:10.1021/ja00405a037
日期:1981.7
The reactions in benzene of methyl, ethyl, and isopropyl perchlorates with N,N-dimethylanilines, to yield precipitates of the quaternary anilinium perchlorate, proceed with second-order kinetics and exhibit a large negative entropy of activation. At 25.0/sup 0/C, Hammett rho values of -3.05, -2.86, and -2.78, respectively, indicate appreciable bonding to the nitrogen within the transition state. In
甲基、乙基和高氯酸异丙酯在苯中与 N,N-二甲基苯胺反应生成高氯酸季苯胺沉淀,以二级动力学进行,并表现出大的负活化熵。在 25.0/sup 0/C 下,Hammett rho 值分别为 -3.05、-2.86 和 -2.78,表明与过渡态内的氮有明显的结合。在与高氯酸甲酯反应时,对氰基和对硝基衍生物需要介于 sigma/sup n/ 和 sigma/sup -/ 之间的值,并且 -1.58 的 rho/sup r/ 参数(由 Young 和 Jencks 定义)是表明的。对亚硝基衍生物的反应比人们预测的要快得多,有人提出亲核中心是氧而不是氮。在与 N,N-二甲基苯胺以 25.0/sup 0/C 反应时,高氯酸甲酯与甲基-d/sub 3/高氯酸对比导致ak/sub H//k/sub D/值为0.942,与碘甲烷对比导致ak/sub MeOClO3//k/sub MeI/比值1170. 目前的