Investigation the Reaction Mechanism from Phenylacetaldehyde and Benzylamine to Polysubstituted Imidazole Catalyzed by Ι2

Abstract

The reaction mechanism from phenylacetaldehyde and benzylamine to polysubstituted imidazole catalyzed by Ι2 was studied by the density functional theory. All of the reactants, intermediates, transition states and product were optimized at B3LYP/6-31+G(d) level. The single point energy and zero point energy correction were calculated for the optimized configuration of each compound at B3LYP/6-311++G(d,p) level. Transition states have been confirmed via vibration analysis and intrinsic reactions coordinate (IRC), and nature bond orbital (NBO) and atoms in molecules (AIM) theories have been used to analysis orbits interaction and bond natures. Our results showed that the activation energy of the rate-determining step was 514.32 kJ•mol without I2-catalyzed, however, the activation energy of the rate-determining step was 145.94 kJ•mol -1 with I2-catalyzed. It indicated that I2 catalyst promoted reaction effectively, and the C—H bond of ethyl of phenylacetaldehyde was activated by I2. In addition, polarized continuum model (PCM) method was adopted to discuss the effects of solvation. All calculations were consistent with experiments. It is predicted that the organic solvent dimethyl sulfoxide (DMSO) can effectively improve the reaction yield.