四氢双环戊二烯硝基衍生物的热力学性质与爆轰性能的理论研究

Thermodynamic Properties and Detonation Performance for Nitro Derivatives of THDCPD by Density Functional Theory

在B3LYP/6-31G水平上对四氢双环戊二烯(THDCPD)的系列硝基衍生物进行了几何构型优化和振动频率计算,并采用统计热力学原理求得不同温度下的热容及焓。通过设计等键反应,获得了各衍生物的标准生成焓。用Monte-Carlo方法和自编程序,基于0.001 e.bohr-3等电子密度面所包围的体积空间求得分子平均摩尔体积和理论密度。以理论计算得到的密度和标准生成焓为基础,用Kamlet-Jacobs方程估算标题物的爆速和爆压。计算结果表明,THDCPD硝基衍生物的总能量与硝基数目有很好的线性相关性,且桥式异构体衍生物的稳定性普遍高于挂式;预计其热解引发键始于C—N键,而不是骨架C—C键的均裂;其焓随温度升高急剧增大,而热容随温度上升其增幅则逐渐减小;随衍生物中硝基数目增多,其爆速和爆压等计算值迅速增大。

The geometries of tetrahydrodicyclopentadienes（THDCPD） and its derivatives were optimized at the B3LYP/6-31G level, vibration frequency analysis was also involved. The heat capacity and enthalpy at different temperatures were obtained by statistic thermodynamics. In order to calculate standard enthalpies of formation for the derivatives of THDCPD, isodesmic reactions were designed. The average molar volume and theoretical density were estimated using the Monte-Carlo method based on 0. 001 e · bohr^-3 density space. Furthermore, the detonation velocity and pressure of the derivatives were estimated by the Kamlet-Jacbos equation. Results show that the total energies with the number of nitro groups are linear, and the derivatives of endo-THDCPD is more stable than the exo ones. The possible mechanism may be started by C-NO2 bond breaking, not the homogeneous cleavage of framework C-C bond. With the temperature increasing, the heat capacity and enthalpy increase, and the increments of heat capacity is degressive, which is conversed to the enthalpy. Also,the detonation velocity and pressure increase evidently with the increasing of the nitro groups＇ number.