脯氨酸离子液体催化CO_2合成碳酸丙烯酯机理的密度泛函理论研究  

Density functional theory studies on the mechanism of the synthesis propylene carbonate by CO_2 catalyzed proline ionic liquids

作　　者：绪连彩[1] 张智强[1] 彭琼阳 毛明[1] 邵晨[1] 蒋玲[1] 王国庆[1] 

机构地区：[1]郑州轻工业学院材料与化学工程学院,河南郑州450001

出　　处：《轻工学报》2016年第1期89-95,共7页Journal of Light Industry

基　　金：国家自然科学基金委河南省联合基金项目(U1204209)

摘　　要：用密度泛函理论研究了脯氨酸离子液体催化CO2合成碳酸丙烯酯的可能反应路径.在M06/6-31+G(d)理论水平上优化反应体系的平衡态和过渡态的几何结构、通过频率分析验证平衡态和过渡态的结构、通过内禀坐标分析确认过渡态与平衡态的连接关系后,在M06/6-311++G(2d,p)理论水平上计算了各点的单点能.结果表明,脯氨酸负离子可以活化催化剂前体2,4-戊二酮,使其失去亚甲基上的质子而形成碳负离子,进而催化CO2合成碳酸丙烯酯;2,4-戊二酮负离子还可以被CO2羧基化,羧基化的2,4-戊二酮负离子催化活性更强,但是羧基化是热力学不利的过程.The possible reaction paths of synthesis of propylene carbonate catalyzed by praline ionic liquid were studied by density functional theory （DFT）. The geometries of reactants, transition states and products were optimized at M06/6-31 ＋ G（d） theoretical level. All stationary point and transition states were verified according to the number of imaginary frequency through harmonic vibrational analysis, transition states were also confirmed by intrinsic reaction coordinate analysis. Single point energy for each species was recalculated at M06/ 6-311 ＋ ＋ G（2d,p） theoretical level. The results indicated that 2,4-pentanedione was activated by proline anion through a proton transfer reaction to yield 2,4-pentanedione anion which contained a carbon anion. The synthesis of propylene carbonate was catalyzed by the 2,4-pentanedione anion. Ahematively, the 2,4-pentane- dione anion was able to be carboxylated by CO2. The carboxylated 2,4-pentanedione anion showed a higher catalytic activity, however, the carboxylation reaction was a thermodynamic unfavorable process.

关 键 词：密度泛函理论 脯氨酸离子液体 CO2催化 碳酸丙烯酯 

分 类 号：TS03[轻工技术与工程]