Chinese Journal of Organic Chemistry ›› 2023, Vol. 43 ›› Issue (1): 285-294.DOI: 10.6023/cjoc202206027 Previous Articles     Next Articles



凌琳a, 王健b, 李婧c, 李玉学a,*(), 吕龙a,*()   

  1. a 中国科学院上海有机化学研究所 院能量调控材料重点实验室 上海 200032
    b 北京系统工程研究所 北京 100034
    c 中国兵器科学研究院 北京 100089
  • 收稿日期:2022-06-17 修回日期:2022-07-20 发布日期:2022-08-17
  • 通讯作者: 李玉学, 吕龙
  • 基金资助:

Broken-Symmetry Density Functional Theory Study on Pyrolysis Mechanisms of 3-Nitro-1,2,4-triazol-5-one (NTO)

Lin Linga, Jian Wangb, Jing Lic, Yuxue Lia(), Long Lua()   

  1. a CAS Key Laboratory of Energy Regulation Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032
    b Beijing System Engineering Institute, Beijing 100034
    c Ordnance Science Institute of China, Beijing 100089
  • Received:2022-06-17 Revised:2022-07-20 Published:2022-08-17
  • Contact: Yuxue Li, Long Lu
  • Supported by:
    National Natural Science Foundation of China(22175197)

Homolytic cleavage of covalent bonds is very common during the pyrolysis of energetic molecules. However, instead of locating the transition state and calculating the free energy barrier ΔG, the bond dissociation energy (ΔH, BDE) is usually considered as the “energy barrier” of the homo-cleavage processes. This simplification brings large errors. In the present work, several pyrolysis pathways of 3-nitro-1,2,4-triazol-5-one (NTO) were studied using broken-symmetry density functional theory method (BS-UB3LYP/6-311+G**). Each transition state of homolytic cleavage was located. The results show that the best pyrolysis pathway under the experimental conditions proceeds via the homolytic cleavage of the C—NO2 bond and the subsequent radical recombination, the energy barrier of the rate-determining step is 216.9 kJ•mol–1 (523 K). Then, NO can promote the subsequent ring-opening, and finally yielding HNCO, N2O and CO. Further reactions between these small molecules lead to NO2, N2 and CO2. These products are consistent well with the experimental observations.

Key words: 3-nitro-1,2,4-triazol-5-one (NTO), energetic materials, pyrolysis mechanism, BS-UDFT (Broken Symmetry Density Functional Theory), open-shell singlet diradical, homolytic cleavage, theoretical study