Thermodynamic study of the mechanism of formation of acrylamide using density functional theory.

摘要

The reaction mechanism for the formation of acrylamide from the reactants of asparagine and glyoxal were investigated by quantum chemical calculations using density functional theory. The formation of acrylamide in food products is poorly understood, although it has been extensively invested by analytical studies using GC/MS and LC/MS. There is no clear picture of the reaction mechanism. Two possible pathways of acrylamide formation were proposed from GC/MS and LC/MS studies, but do not give a clear picture of which pathway is more favorable. In this study, computational methods were used to evaluate possible pathways based on relative energies, enthalpies, and free energies of possible intermediates. Further analyses were then conducted to determine the transition state with the optimized geometries of the intermediates to determine the most favorable pathway for acrylamide formation. This was determined by evaluating the transition states of the intermediates in the reaction with computational methods. This study found that the decarboxylation intermediate is the rate determining step, because based on the relative free energy compared with the rest of the mechanism, it was the highest. After the intermediate decarboxylates, two possible pathways occur to form acrylamide. This study determined the formation of a 3-aminopropionamide intermediate and glyoxal was found to be more favorable as opposed to a direct elimination of an imine.