DOI: 10.36347/sjet.2022.v10i07.007

Pages: 170-177

In this paper, density functional theory (DFT) was applied to study the isomerization process and fragmentation mechanism of deprotonated alanine ions ([β-Ala–H]–) at B3LYP/6-311++G (2df, 2pd) level. Deprotonated α-alanine ions generally have lower energies than deprotonated β-alanine ions, and 1a2 is the most stable structure. In the isomerization process, the reaction barrier (ΔG≠) required for hydrogen transfer is the highest, that the pathway of NH3- loss reaction to the product p3 is the only forward spontaneous reaction in thermo dynamics and NH3-loss reaction is also easier than H2O-loss reaction in kinetics. Meanwhile, the effect of temperature on the optimal H2O- and NH3-loss reaction paths of the deprotonated α- and β-alanine ions were investigated, and the results showed that temperature had little effect on H2O- and NH3-loss reactions. In addition, different calculation methods and focus analysis of the basis group were investigated, and the results show that B3LYP/6-311++G (2df, 2pd) level is suitable for this study.