Department of Chemistry, Military Institute of Engineering, Praça Gen Tiburcio, 80, Rio de Janeiro, RJ, Brazil.
J Mass Spectrom. 2020 Jun;55(6):e4513. doi: 10.1002/jms.4513. Epub 2020 Mar 25.
Tabun (ethyl N,N-dimethylphosphoramidocyanidate), or GA, is a chemical warfare nerve agent produced during the World War II. The synthesis of its analogs is rather simple; thus, it is a significant threat. Furthermore, experiments with tabun and other nerve agents are greatly limited by the involved life risks and the severe restrictions imposed by the Chemical Weapons Convention. For these reasons, accurate theoretical assignment of fragmentation pathways can be especially important. In this work, we employ the Quantum Chemistry Electron Ionization Mass Spectra method, which combines molecular dynamics, quantum chemistry methods, and stochastic approaches, to accurately investigate the electron ionization/mass spectrometry (EI/MS) fragmentation spectrum and pathways of the tabun molecule. We found that different rearrangement reactions occur including a McLafferty involving the nitrile group. An essential and characteristic pathway for identification of tabun and analogs, a two-step fragmentation producing the m/z 70 ion, was confirmed. The present results will be also useful to predict EI/MS spectrum and fragmentation pathways of other members of the tabun family, namely, the O-alkyl/cycloalkyl N,N-dialkyl (methyl, ethyl, isopropyl, or propyl) phosphoramidocyanidates.
沙林（乙基 N,N-二甲基磷酰胺氰酸盐），或 GA，是二战期间生产的一种化学战神经毒剂。其类似物的合成相当简单；因此，它是一个重大威胁。此外，由于涉及生命风险以及《化学武器公约》的严格限制，沙林和其他神经毒剂的实验受到极大限制。出于这些原因，准确的理论碎片途径分配可能尤为重要。在这项工作中，我们采用了量子化学电子离子质谱法，该方法结合了分子动力学、量子化学方法和随机方法，准确研究了沙林分子的电子电离/质谱 (EI/MS) 碎片谱和途径。我们发现包括腈基的麦拉弗蒂重排反应等不同的重排反应。我们确认了产生 m/z 70 离子的两步碎裂，这是鉴定沙林和类似物的重要且特征性途径。这些结果对于预测沙林家族的其他成员（即 O-烷基/环烷基 N,N-二烷基（甲基、乙基、异丙基或丙基）磷酰胺氰酸盐）的 EI/MS 光谱和碎裂途径也将是有用的。
