摘要
为确定大气中偏二甲肼(UDMH)转化为亚硝基二甲胺(NDMA)的反应路径,采用量子化学方法对UDMH在大气中氧化生成NDMA的反应机理进行了研究,在B3LYP/6-311+G(d,p)和M06-2X/6-311+G(d,p)水平上对反应体系的反应物、中间体、过渡态及产物进行了几何构型优化和频率计算,在CCSD(T)/aug-cc-pVTZ水平下进行单点能校正,构筑了反应的势能剖面。结果表明,UDMH氧化反应引发的过程是一个脱氢或加氧过程;考虑到大气中氧化剂(HO·/O_3/O_2)的浓度,不同氧化剂引发UDMH反应速率的比例关系为v(O_3)≈10~4×v(HO·)≈10~8×v(O_2)。因此UDMH在大气氧化的引发过程中最主要是被O_3氧化,UDMH摘除氢原子后生成中间体(CH_3)_2NN(H)·(IM1)。IM1在大气环境中HO·、HO_2·及O_3作用下都可以转化为NDMA,臭氧参与过程将降低反应活化能,促进NDMA在大气中生成。
To determine the reaction pathway of unsym?dimethylhydrazine (UDMH) to nitrosodimethylamine (NDMA) in the atmosphere, the reaction mechanism of UDMH oxidation to NDMA in the atmosphere was studied using quantum chemical method. The geometric configuration optimization and frequency calculation of reactants, intermediates, transition states and products of the reaction system were carried out at B3LYP/6?311+G(d,p) and M06?2X/6?311+G(d,p) levels. The single points energies of the species were corrected at the CCSD(T)/aug?cc?pVTZ level and the potential energy surface profile for the reactions was constructed. Results show that the oxidation initiation of UDMH is a dehydrogenation or oxygenation process. Considering the concentration of oxidants in the atmosphere, the ratio of reaction rate of UDMH initiated by different oxidants is: v(O3)≈104×v(HO·)≈108 ×v(O2) .The oxidation of UDMH is mainly trigged by ozone, forming (CH3)2NNH(IM1) after the removal of hydrogen atoms. Then IM1 can be converted into NDMA under the action of HO·, HO2·, O3 in the atmosphere environment. Ozone participation in the process will reduce the activation energy of the reaction and promote the formation of NDMA in the atmosphere.
作者
黄丹
刘祥萱
王煊军
杨玉雪
慕晓刚
HUANG Dan;LIU Xiang-xuan;WANG Xuan-jun;YANG Yu-xue;MU Xiao-gang(The Rocket Army Engineering University,Laboratory of Safety Technology of Missile Equipment,Xi′an 710025,China)
出处
《含能材料》
EI
CAS
CSCD
北大核心
2019年第1期35-40,90,共7页
Chinese Journal of Energetic Materials
