密度泛函理论方法研究Mn^2+催化丙氨酸反应的机理及催化活性

Density Functional Theory Study on Catalytic Activity and Mechanism of Alanine Conversion Reaction Indused by Mn^2+

采用密度泛函理论的BP86-D3方法研究了Mn^2+催化丙氨酸转化反应的机理及催化活性.得到15个稳定构型和12个过渡态,最稳定构型的结合自由能为-710.8kJ·mol^-1.Mn^2+可以催化丙氨酸发生质子迁移反应、手性转化反应、裂解失CO反应和裂解失H2O反应;对应的吉布斯自由能垒分别为7.7kJ·mol^-1、78.7kJ·mol^-1、166.4kJ·mol^-1和225.2kJ·mol^-1.丙氨酸质子迁移反应和手性转化反应通道的决速步基元反应相同,自由能垒是119.1kJ·mol^-1,相应反应较易发生.丙氨酸裂解反应通道的最高自由能垒为225.2kJ·mol^-1,反应较难发生.

BP86-D3 method was applied to investigate the catalytic activity and mechanism of alanine conversion reaction indused by Mn^2+.15 stable conformations and 12 transition states were obtained,the bonding free energy of the most stable conformer is-710.8kJ·mol^-1.With the catalytic action on alanine by Mn^2+,4 kinds of reactions(proton transfer,chiral inversion,CO loss from pyrolysis and H2O loss from pyrolysis)can be induced,corresponding activation free energy is 7.7,78.7,166.4 and 225.2kJ·mol^-1.The highest activation free energy of the rate-determining step of the reaction channels of proton transfer reaction and chiral inversion reaction all are 119.1kJ·mol^-1,it means above reactions are relatively easy.The highest activation free energy of channel of alanine pyrolysis reaction is 225.2kJ·mol^-1,so this reaction is more difficult.