气相中S(N)2和E2反应的氘动力学同位素效应：实验与理论的比较

Deuterium kinetic isotope effects in gas-phase S(N)2 and E2 reactions: comparison of experiment and theory.

作者信息

Villano Stephanie M, Kato Shuji, Bierbaum Veronica M

机构信息

University of Colorado, Department of Chemistry and Biochemistry, 215 UCB, Boulder, Colorado 80309-0215, USA.

出版信息

J Am Chem Soc. 2006 Jan 25;128(3):736-7. doi: 10.1021/ja057491d.

DOI:10.1021/ja057491d

PMID:16417360

Abstract

The competition between bimolecular nucleophilc substitution and base-induced elimination is investigated through kinetic isotope effect measurements for gas-phase reactions of RCl + ClO- (R = methyl, ethyl, isopropyl, and tert-butyl) utilizing a FA-SIFT instrument. The overall reaction rate constants and the kinetic isotope effect for the reaction of C2H5Cl + ClO- are compared to computational results. [Hu, W. P.; Truhlar, D. G. J. Am. Chem. Soc. 1996, 118, 860.] Experimental results show that as the degree of substitution in the neutral reactant increases the E2 channel becomes dominant. The systematic change in the overall kinetic isotope effects indicates that, for the reaction of ClO- with C2H5Cl, both the SN2 and E2 pathways do occur, as predicted by computation; however the experimental reaction rate constants and KIE deviate strongly from the computational result.

摘要

利用流动漂移管选择离子流管（FA-SIFT）仪器，通过对RCl + ClO-（R = 甲基、乙基、异丙基和叔丁基）气相反应进行动力学同位素效应测量，研究了双分子亲核取代与碱诱导消除之间的竞争。将C2H5Cl + ClO-反应的总反应速率常数和动力学同位素效应与计算结果进行了比较。[Hu, W. P.; Truhlar, D. G. J. Am. Chem. Soc. 1996, 118, 860.] 实验结果表明，随着中性反应物取代度的增加，E2通道占主导地位。整体动力学同位素效应的系统变化表明，对于ClO-与C2H5Cl的反应，正如计算所预测的那样，SN2和E2途径都确实发生；然而，实验反应速率常数和动力学同位素效应与计算结果有很大偏差。