2-(2-羟基苯亚甲基胺)-4，6-二羟基-嘧啶的质子转移异构化反应  

Proton-Transfer Isomerization Reactions of 2-(2-Hydroxybenzylidenamino)pyrimidine-4,6-diol

作　　者：周子彦[1] 刘敏[2] 苏忠民[3] 谢玉忠[2] 丁慎德[1] 王华静[1] 

机构地区：[1]山东理工大学化学工程学院,山东淄博255049 [2]延边大学理学院化学系,吉林延吉133002 [3]东北师范大学化学学院功能材料化学研究所,长春130024

出　　处：《物理化学学报》2011年第9期2035-2042,共8页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20703008);山东省自然科学基金(ZR2009BL024)资助项目~~

摘　　要：为了探索2-(2-羟基苯亚甲基胺)-4,6-二羟基-嘧啶(M1)分子醇式和酮式结构互变异构化的反应机理, 利用密度泛函理论(DFT)方法, 在B3LYP/6-311+G(d, p)基组水平上, 对M1化合物异构化反应的势能面进行了研究, 在探讨各种可能的反应途径中, 发现单体至少有8种异构体和10种过渡态. 结果表明: 2-(2-羟基苯亚甲基胺)-6-羟基-4(3H)嘧啶酮(M6)不论是单体、与水形成的配合物, 还是二聚体, 比其相对应的异构体能量低, 表明在通常情况下是以M6形式稳定存在的; 在考察的可能反应途径中, 直接进行的分子内质子转移过程需要的活化自由能为143.8 kJ·mol-1, 水助催化时, 反应的活化自由能为38.9 kJ·mol-1, 二聚体双质子转移的活化自由能为0.6 kJ·mol-1, 二聚体双质子转移所需活化自由能最低, 在室温下就可以进行, 由此可见氢键在降低反应活化能方面起着重要的作用.To determine the tautomerism mechanism between the enol form and the keto form of 2- （2-hydroxybenzylidenamino）pyrimidine-4,6-diol （M1） the potential energy surface of the isomerization was studied using density functional theory （DFT） calculations at the B3LYP/6-311 ＋G（d, p） level. We found that there were at least 8 isomers and 10 transition states in the possible reaction pathways. All the possible processes of the reaction were studied. The results showed that the energy of 6-hydroxy-2-（2- hydroxybenzylideneamino） pyrimidine-4（3H）-one （M6） was lower than those of the other isomers in the form of a monomer, a hydrate, and a dimer. Therefore, it was the most stable isomer. In these possible reaction pathways the activation free energy required for intramolecular prototropy was 143.8 k J·mol^-1 and for the proton transfer process that was catalyzed by water was 38.9 kJ·mol^-1. The activation free energy in the double-proton transfer of the dimer was 0.6 kJ·mol^-1, which was the lowest value. The latter pathway was feasible at room temperature. This implies that hydrogen bonding plays an important role in depressing the activation energy of the reaction.

关 键 词：2-(2-羟基苯亚甲基胺)-4 6-二羟基-嘧啶 密度泛函理论 互变异构 质子转移 

分 类 号：O626.41[理学—有机化学]