Received November 2, 2005

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 S_N2 and E2 pathways do occur, as predicted by computation; however the experimental reaction rate constants and KIE deviate strongly from the computational result.

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