基于电子结构水平调控新型起爆药分解反应机理

Controlling Decomposition Reaction Pathways of Novel Primary Explosives at Electronic Structure Level

揭示电子结构与分解反应机理之间的联系是设计新型起爆药的关键.本文应用密度泛函理论结合Gaussian 09程序包对4氨基-5-巯基-1,2,4三唑和4-氨基-5-巯基-3-硝基-1,2,4三唑在基态、电荷态以及最低三重激发态(T1)下的电子结构和微观分解机理进行了系统的研究.结合热力学和动力学方法探索分子带电和激发电子对其分解反应机理的影响.研究表明,对于不同取代基脱离三唑环,氨基在中性条件下更容易解离.对于三唑开环分解,环上的“N4-C5”键最容易裂解、对于4-氨基-5-巯基-1,2,4三唑,激发电子使“N4-C5”键直接断裂并释放13.83 kJ/mol的热量.对于4-氨基-5-巯基-3-硝基-1,2,4三唑而言,当分子带正电荷时,CONO异构化为主导反应,质子转移被阻碍.当分子带负电或其电子被激发时,质子转移优先发生.在电子结构水平上,本文通过分子带电或激发电子来调控三唑环上不同取代基解离、三唑开环反应、异构化反应以及质子转移,揭示三唑类起爆药的分解反应机理,为三唑类起爆药的应用提供科学依据.

Revealing the relationship between electronic structures and the decomposition mechanism is the key to explore novel primary explosives.A systematic investigation on electronic structures and microscopic decomposition pathways of 4-amino5-mercapto-1,2,4-triazole(AMTA)and 4-amino5-mercapto-3-nitro-1,2,4-triazole(AMNTA)in the ground,charged,and excited states(S0→T1)has been analyzed with density functional theory.The effect of electrifying molecules and exciting electrons on the decomposition mechanism has been clarified by thermodynamics and kinetics.This study shows that the neutral amino dissociation from the triazole ring has an advantage among different substituents dissociation.For AMTA,electrifying the molecule can make the ring cleavage occur easily at the N4−C5 site,and exciting electrons makes the triazole ring decompose directly and release 3.3 kcal/mol of heat.For AMNTA,positively electrifying the molecule makes CONO isomerization become the dominant reaction and hinders the H-transfer reaction.When the molecule is electrified negatively or its electrons are excited,H-transfer will take place preferentially.This work sheds light on how to control the decomposition pathways of novel primary explosives at the electronic structure level by the means of electrifying molecules and exciting electrons.