BTATz晶体及其共晶的热分解及释放氮气机理:从头算分子动力学模拟

Thermal Decomposition and N_(2) Formation Mechanisms of BTATz Crystal and Its Cocrystal:Ab initio Molecular Dynamic Simulations

为了分析BTATz与pyrazine分子形成共晶后高温热分解机理的变化,采用从头算分子动力学(AIMD)方法,对BTATz晶体及其共晶BTATz/pyrazine的热分解过程进行了模拟。结果表明,在BTATz晶体中,BTATz分子的初始分解路径包括四唑环上N—H键断裂、四唑环上N—N键断裂和H自由基与四嗪环相连生成N—H键;在BTATz/pyrazine共晶中,BTATz分子的分解路径与在BTATz晶体中的情况有所不同。在这两种晶体中,N_(2)的生成速率不同,但是最终生成的N_(2)数量是相同的。在这两种晶体中N_(2)的生成机理相似,都是由四嗪环或四唑环反应得到的,仅仅是N_(2)产生的时间不同。这表明pyrazine分子的存在影响BTATz分子的初始分解过程,但不会影响产物的生成机理和最终数量。

To investigate the changes of thermal decomposition mechanism after cocrystal formation from BTATz and pyrazine molecular,ab initio molecular dynamics(AIMD)method was used to simulate the thermal decomposition process of BTATz crystal and BTATz/pyrazine cocrystal.The results indicate that the initial decomposition pathways of the BTATz molecule in its crystal include:the N—H bond cleavage in tetrazole ring,the N—N bond cleavage in tetrazole ring,and the formation of N—H bond by the tetrazine ring connected with the H radical.However,different initial decomposition pathways were found during the decomposition of the BTATz/pyrazine cocrystal.The generation rates of N_(2) are different in the thermal decomposition process of the two crystals,while the numbers of N_(2) are equal.The generation pathways of N_(2) are similar for the two crystals,which involve the reactions from the tetrazole or tetrazine ring,nothing but generate at the different times.It is showed that the presence of pyrazine will affect the initial decomposition pathway rather than the generation mechanism and the numbers of products.