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采用密度泛函B3LYP方法,在6-31+G**基组水平上对p-羟基苯丙酮酸质子转移引起的烯醇式-酮式互变异构反应机理进行了计算研究,获得了互变异构过程的反应焓、活化能、活化吉布斯自由能和质子转移反应的速率常数等参数。Onsager反应场溶剂模型用于水相和甲醇相的计算,计算结果表明,p-羟基苯丙酮酸无论在气相还是水相、甲醇相中,其酮式异构体都是最稳定的存在形式,烯醇式异构体也会以一定量共存。气相中孤立分子内质子转移几何构型改变较显著,异构化反应需要较大的活化能,不利于发生质子转移,Onsager模型计算方法对质子转移反应的影响较小。
The density functional B3LYP method was used to calculate the enol-keto tautomerization reaction induced by proton transfer of p-hydroxyphenylpyruvate at 6-31 + G ** basis level. Reaction enthalpy, activation energy, rate constant of Gibbs free energy and proton transfer reaction in the variation process. Onsager reaction field solvent model was used to calculate the water phase and the methanol phase. The calculated results show that p-hydroxyphenylpyruvate is the most stable form of the ketone isomer in the gas phase, the aqueous phase and the methanol phase. Enol isomers will also be a certain amount of coexistence. The geometrical changes of proton transfer in isolated molecules in the gas phase change more significantly. The isomerization reaction requires larger activation energy, which is not conducive to the proton transfer. The Onsager model has little effect on the proton transfer reaction.