Abstract
In order to explore the catalytic effect of alcohols on the 1,3-proton
transfer of 1,1-diphenyl-N-(1-phenylethylidene) methylamine, the
reaction potential energy surface was systematically studied at the
theoretical level of ωB97-MV / def2-QZVPP // PBE0(D3BJ) / 6-31G**. The
results show that the catalytic mechanism of benzyl alcohol can be
divided into the acid channel and basic channel, in which the acid
channel is the dominant one. In the first step, benzyl alcohol
protonated the nitrogen atom of imine to form imine cation and benzyl
alcohol anion, and the newly formed benzyl alcohol anion preferentially
combined with the proton on C1; in the second step, benzyl alcohol
continued to protonize the C3 atom, and the newly formed benzyl alcohol
anion combined with the hydrogen on nitrogen, thus completing the whole
proton migration process. By means of wave function analysis, it is
proved that the stronger the hydrogen bond (O–H···N) is, the lower the
free energy barrier is. When alcohols with lower pKa values are used as
catalysts, the reaction barrier will be lower.