氢氰酸与水的异构化反应密度泛函理论研究

DFT Study on the Isomerization Reaction of Hydrocyanic Acid and Water

采用电子结构理论中的B3LYP密度泛函方法(DFT),在B3LYP/6-311++G(3df,2pd)水平上,在气相和水相中分别研究了异氰酸与水通过分子间氢键首尾相连,形成五元环过渡态,再转换成氢氰酸的异构化反应。计算结果表明,在水相中异构化过程的活化能比在气相中低,无论在气相还是在水相中异氢氰酸通过水氢键转化成氢氰酸容易些,而氢氰酸由水氢键转化成异氢氰酸相对要困难些,分子间氢键和溶剂化效应在异构化反应过程中起到重要的作用。

The reaction mechanism of the isomerization：HNC→HCN has been studied by means of density functional theory （DFT） at the level of B3LYP/6-311 ＋ ＋ G（3df,2pd）. Hydrocyanic acid and water proceed via a five-centred transition states then transformed by its exterior hydrogen-bond ; The results show that the activation energy of the isomerizing reaction in the aqueous phase is lower than that in the gas phase. It is likely that the hydrogen bonds formed in the complexes and the solvent effect play an important role.