J Org Chem. 2003 Oct 17;68(21):8232-5. doi: 10.1021/jo034799j.

Calculations of substituent and solvent effects on the kinetic isotope effects of Menshutkin reactions.

The Journal of organic chemistry

Emilia Owczarek, Wojciech Kwiatkowski, Michał Lemieszewski, Adam Mazur, Michał Rostkowski, Piotr Paneth

PMID: 14535807 DOI: 10.1021/jo034799j

Abstract

Nitrogen, deuterium, halogen, and carbon kinetic isotope effects have been modeled for the Menshutkin reaction between methyl halides and substituted N,N-dimethylaniline at the HF/6-31G(d) level of theory augmented by the C-PCM continuum solvent model for several solvents. Systematic changes in geometries of the transition states and Gibbs free energies of activation have been found with phenyl ring substituents, solvent, and the leaving group. Kinetic isotope effects also change systematically; however, these changes are predicted to be small, inside the usual precision of the experimental measurements. On the contrary, no correlation has been found between the kinetic isotope effects and the Hammett constants for para substituents. Thus opposite to previous assumptions, our results indicate that kinetic isotope effects on the Menshutkin reaction cannot be used to predict the position of the transition state on the reaction coordinate.

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• Journal Article