稀醋酸/水溶液中单个醋酸与水分子的氢键结构  

Hydrogen bonding of single acetic acid with water molecules in dilute aqueous solutions

作　　者：蒲亮[1,2,3,4] 孙岳明[1] 张志炳[2,3,4] 

机构地区：[1]东南大学化学化工学院,南京211189 [2]南京大学分离工程研究中心 [3]介观化学教育部重点实验室 [4]南京大学化学化工学院,南京210093

出　　处：《中国科学：化学》2010年第4期357-363,共7页SCIENTIA SINICA Chimica

基　　金：江苏省博士后科研资助计划(编号:0901001C);国家自然科学基金(编号:20876072);江苏省自然科学基金(编号:KB2008023)的资助

摘　　要：在醋酸/水体系的工业分离中,溶液中的氢键对分离效率有很大影响.本文采用两种第一性原理方法,即从头算分子动力学模拟(AIMD)和量子化学计算(QCC),对由单个醋酸和不同水分子所组成聚合体的氢键相互作用进行了研究,采用极化统一模型和自洽反应场模型计算得到了聚合体在水溶液中的热力学数据.从QCC计算的气相和水溶液中的聚合自由能表明六元环在两种状态下都为最优结构,热力学数据反映出的各种结构的相对稳定性与AIMD模拟的环分布符合得相当一致.研究表明,由于存在醋酸和水分子间的氢键作用,稀醋酸/水溶液中的醋酸分离要比在浓醋酸溶液中困难得多.In separation processes,hydrogen bonding has a very significant effect on the efficiency of isolation of acetic acid（HOAc） from HOAc/H2O mixtures.This intermolecular interaction on aggregates composed of a single HOAc molecule and varying numbers of H2O molecules has been examined by using ab initio molecular dynamics simulations（AIMD） and quantum chemical calculations（QCC）.Thermodynamic data in aqueous solution were obtained through the self-consistent reaction field calculations and the polarizable continuum model.The aggregation free energy of the aggregates in gas phase as well as in aqueous system shows that the 6-membered ring is the most favorable structure in both states.The relative stability of the ring structures inferred from the thermodynamic properties of the QCC is consistent with the ring distributions of the AIMD simulation.The study shows that in dilute aqueous solution of HOAc the more favorable molecular interaction is the hydrogen bonding between HOAc and H2O molecules,resulting in the separation of acetic acid from the HOAc/H2O mixtures with more difficulty than usual.

关 键 词：醋酸 氢键 从头算 分子动力学 自由能 

分 类 号：O621.13[理学—有机化学]