A Theoretical Study of Methanol Vinylation Reaction Mechanism

The mechanism of base-catalyzed nucleophilic addition of methanol to acetylene triple bond (vinylation) in dimethyl sulfoxide (DMSO) and methanol solution was studied using the MP2/6-311++G**//B3LYP/6-31G* calculations with solvent effects included via continuum model. The proton abstraction from methanol by nondissociated alkali in DMSO surrounding media to form alkali metal methoxides CH3OM (M = Li, Na, K) was found to occur with a negligible activation barrier. The reasons for facilitation of base-catalyzed alcohol vinylation in the DMSO medium are discussed in the light of both poor solvation of methoxide ion and a specific coordination of reactants by nondissociated alkali in the MOH/DMSO mixtures. (C) 2008 Wiley Periodicals, lnc. Int J Quantum Chem 108: 2630-2635, 2008