Nitrogen and deuterium isotope effects on quaternization of N,N-dimethyl-p-toluidine

Abstract

A nitrogen kinetic isotope effect k 14 /k 15 =1.0019±0.0001, a deuterium kinetic isotope effect k H3 /k D3 =0.83±0.04, and a solvent deuterium isotope effect k H /k D =1.00±0.05 were measured on the Menschutkin reaction between methyl iodide and N,N-dimethyl-p-toluidine at 25°C in methanol. Semiempirical quantum mechanical calculations of kinetic isotope effects of deuterium, carbon, and nitrogen on the same reaction were performed with use of an AM1 Hamiltonian. A late transition state is proposed on the basis of a comparison between experimental and theoretical values of isotope effects