水溶液中亚硝基甲烷与甲醛肟之间互变异构反应的理论研究  

Theoretical Study of the Tautomerization of Nitromethane to Formaldoxime in Aqueous Solution

作　　者：梁国明[1] 任译[2] 

机构地区：[1]重庆师范大学化学学院,重庆400047 [2]四川大学化学学院,成都610064

出　　处：《化学学报》2005年第23期2163-2168,共6页Acta Chimica Sinica

基　　金：重庆市教委科技(No.kj050805)资助项目.

摘　　要：采用超分子-连续介质(PCM)模型,在密度泛函B3LYP/6-311++G**水平上对水溶液中亚硝基甲烷异构化反应的机理进行了理论研究.结果表明,在水溶液中亚硝基甲烷可以通过两条反应途径(I和II)经质子迁移得到更稳定的重排产物——反式甲醛肟,但优势反应途径与在气相反应不同.在水溶液中亚硝基甲烷异构化反应最有可能的途径I是通过氢迁移先生成顺式甲醛肟,然后绕N—O键旋转生成更稳定的反式甲醛肟.并且由于水分子的催化作用使得反应活化能从气相中240.6和196.2kJ/mol分别降低至水溶液中的61.7和92.1kJ/mol.The mechanism of the tautomerization of nitromethane to formaldoxime in aqueous solution has been investigated at the level of B3LYP/6-311 ＋ ＋ G^＊＊ using the supramolecular/continuum model. Calculated results indicate that the isomerization of nitromethane to more stable trans-formaldoxime can proceed via two different reaction channels, but the favorable reaction pathway in aqueous is different from the one in the gas phase. It is more favorable that the tautomeric reaction involves the formation of cis-formaldoxime and a subsequent rotation about the N-O bond to form the trans-formaldoxime in aqueous solution. Moreover, the activation energies were reduced from 240.6 and 196.2 kJ/mol in the gas phase to 61.7 and 92.1 kJ/mol in aqueous solution, respectively, due to the catalysis of water.

关 键 词：亚硝基甲烷 甲醛肟 水助互变异构反应 密度泛函 

分 类 号：O621.25[理学—有机化学]