亚甲二醇二硝酸酯的构象和热解机理的理论研究

Theoretical Study of Conformation and Thermolysis Mechanism of Methylene Glycol Dinitrate

用量子化学中的ＳＣＦ－ＭＯＭＩＮＤＯ／３，ＭＮＤＯ，ＡＭ１和ＰＭ３方法计算研究了亚甲二醇二硝酸酯（ＭＧＤＮ）的几何构型和电子结构，求得了ＭＧＤＮ的平衡几何构型。不同方法的计算结果均表明，标题物分子中两个ＯＮＯ２均为平面基团，且Ｏ—ＮＯ２键的Ｗｉｂｅｒｇ键级最小，是分子中最弱的键，在分解时可能首先断裂；用ＡＭ１法分别在限制和非限制Ｈａｒｔｒｅｅ－Ｆｏｃｋ（ＲＨＦ和ＵＨＦ）水平上，计算研究了ＭＧＤＮ断裂Ｏ—ＮＯ２键的热解反应，求得了反应活化能。结果发现，ＭＧＤＮ断裂Ｏ—ＮＯ２键的活化能比其他酯的低得多。

SCF MO MINDO/3, MNDO, AM1 and PM3 methods have been employed to study the geometry and electronic structure of the methylene glycol dinitrate (MGDN). The equilibrium geometry is obtained. The calculated results of various methods show that the two ONO 2 groups in MGDN are planar, and the O—NO 2 bonds, of which the Wiberg bond orders are the smallest, are the weakest bonds, and will probably be broken initially during decomposition. The AM1 method has been used to investigate the thermo lysis reaction of MGDN breaking O—NO 2 bond at RHF and UHF levels, respectively. The activation energy of the thermolysis is obtained. It is found that the activation energy of MGDN is much lower than those of other organic esters, implying that MGDN is less stable.