Designed model for the Morita–Baylis–Hillman reaction mechanism in the presence of CaO and CaO modified with ionic liquid as a solid base catalyst: a DFT and MP2 investigation

Abstract

The new model for the Morita–Baylis–Hillman reaction based on the proton transfer were inquired by MP2 and DFT methods with 6-311G++(d, p) basis set combined with IEF-PCM solvent model. We focused on the reaction between acrylonitrile and benzaldehyde, catalyzed by CaO cluster and CaO modified with [Pyr][HSO4] ionic liquid. Our results indicate that in the presence of ionic liquid, the ionic liquid acts as a shuttle for the proton transfer between species in a lower energy pathway. The proton transfer step from enolate to catalyst is predicted to be the rate-limiting step for the whole process. In order to investigate the catalyst basicity, the pKa values of acrylonitrile and methyl acrylate in the presence and absence of the catalyst were measured in DMSO as a solvent. Furthermore, the proton affinities and the basicity of the CaO cluster and CaO modified with [Pyr][HSO4] ionic liquid and its components in the gas phase have been calculated at the same level of theory. Molecular electrostatic potential and valence natural atomic orbital energies in the gas phase for the catalyst have been calculated.