NITROGEN AND DEUTERIUM-ISOTOPE EFFECTS ON QUATERNIZATION OF N,N-DIMETHYL-PARA-TOLUIDINE

A nitrogen kinetic isotope effect k14/k15 = 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-degrees-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 AM1 Hamiltonian. A late transition state is proposed on the basis of a comparison between experimental and theoretical values of isotope effects.