Theoretical study of the reaction mechanism of proton transfer in glycinamide

Abstract

AbstractTo investigate the tautomerism of glycinamide that is induced by proton transfer, we present detailed theoretical studies on the reaction mechanism of both the isolated gas phase and H2O‐assisted proton transfer process of glycinamide, using density functional theory calculations by means of the B3LYP hybrid functional. Twenty‐six geometries, including 10 significant transition states, were optimized, and these geometrical parameters are discussed in detail. The relative order of the activation energy for hydrogen atom transfer of all the conformers has been systematically explored in this essay. For the amido hydrogen atom transfer process, the relative order of the activation energy is: IV < II < III < I, while in the carbonic hydrogen atom transfer process, the relative order is IV > II > III > I. Meanwhile, the most favorable structure for both the amido hydrogen atom transfer and the carbonic hydrogen atom transfer has been found. The involvement of the water molecule not only can stabilize the transition states and the ground states, but can also reduce the activation energy greatly. The superior catalytic effect of H2O has been discussed in detail. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006