Journal of the Chilean Chemical Society
version ISSN 0717-9707
TAN, XIAOJUN et al. DFT STUDY ON THE MECHANISM OF THE ADDITION REACTION BETWEEN CARBENE AND GLYCINE. J. Chil. Chem. Soc. [online]. 2011, vol.56, n.1, pp. 628-630. ISSN 0717-9707. doi: 10.4067/S0717-97072011000100024.
The mechanism of addition reaction between the singlet carbene and glycine has been investigated at the B3LYP/6-311+G* level of theory, including geometry optimization and vibrational analysis for the involved stationary points on the potential energy surface. Computational results suggest that there are two reaction pathways (1) and (2) during the addition process. In the pathway (1), carbene attacks the C=O bond from the H1C1C2 side of glycine to form an intermediate (IM1), which is a barrier-free exothermic reaction. Then, IM1 isomerizes to a product (Pro1) via a transition state (TS1) with a potential barrier of 25.7 kJ/mol. Similarly, in the pathway (2), carbene attacks the C=O bond from the H2C1C2 side of glycine to form an intermediate IM2. Subsequently, IM2 isomerizes to Pro2 via TS2, where the Pro2 and Pro1 are enantiomers actually. The calculated potential barrier of 51.3 kJ/mol is higher than that of the pathway (1). Correspondingly, the reaction energy for the both pathways is -258.5 kJ/mol. Additionally, the atoms in molecules (AIM) theory has also been performed to characterize the bonding interaction and structural features for the addition reaction.
Keywords : Carbene; Glycine; Addition reaction; Density functional theory (DFT).