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采用密度泛函理论的B3LYP方法、微扰理论的MP2方法和自洽反应场(SCRF)理论的smd模型方法,研究了脯氨酸手性转变裸反应机理、水分子的催化作用及水溶剂化效应.结构分析表明:三元环结构过渡态aTS2、五元环结构过渡态aTS2·1H_2O和七元环结构过渡态aTS2·2H_2O的稳定性顺次增加.反应通道研究发现:标题反应有4个通道a,b,c,d.a,b和c通道手性碳上的质子分别以亚氨基为桥、依次以羰基和亚氨基为桥和只以羰基为桥迁移;d通道羧基内质子迁移后,手性碳上的质子再以羰基为桥迁移.势能面计算表明:a通道为优势反应通道,单体气相反应决速步骤吉布斯自由能垒为246.0kJ·mol~(-1);2个水分子的催化使决速步骤自由能垒降为122.6kJ·mol~(-1);2个水分子的催化与水溶剂效应的共同作用,使决速步骤自由能垒降为105.1kJ·mol~(-1).
The B3LYP method of density functional theory, the MP2 method of perturbation theory and the Smd model of self-consistent reaction field (SCRF) theory were used to study the mechanism of proline chiral transition reaction, the catalysis of water molecules and the solvation of water The structure analysis shows that the stability of transition state aTS2, aTS2 · 1H_2O of the five-membered ring structure and aTS2 · 2H_2O of the seven-membered ring structure sequentially increase.The reaction channel study found that there are four The protons on the chiral carbons of channels a, b, c, da, b and c are respectively bridged by imino groups, followed by carbonyl and imino bridges and carbonyl-only bridges as the bridge; The proton on the chiral carbon migrates with carbonyl as a bridge.The potential energy surface calculation shows that channel a is the predominant channel and Gibbs free energy barrier is 246.0 kJ · mol -1 The catalysis of a water molecule reduced the free energy barrier to 122.6 kJ · mol -1 in the rate-determining step. The combined effect of catalysis and water-solvent effect of two water molecules reduced the free energy barrier to 105.1 kJ · mol ~ (-1).