Organophosphorus compounds have a wide range of applications; they are commonly used as drugs or pesticides or in the production of ion batteries. However, some organophosphorus compounds, which were developed as warfare nerve agents, are neurotoxic and potentially lethal to living organisms. On the basis of the literature search, certain properties of these compounds are not well known. Knowledge of thermodynamic properties and the availability of reliable data are fundamental in the development of methods for detecting, treating, and safely analyzing decontamination. For research purposes, substitutes, called simulants, which have similar molecular structures and properties but are less toxic, are often employed. This work presents a thermodynamic study of four organophosphorus nerve agent simulants: trimethyl phosphate, triethyl phosphate, dimethyl methylphosphonate, and diethyl methylphosphonate. Differential scanning calorimeter and a Tian–Calvet type calorimeter were used to analyze their phase behavior and measure the liquid heat capacities, respectively. Vapor pressures were experimentally determined with the static method. Ideal-gas heat capacities were calculated using the R1SM approach, which combines the rigid rotor–harmonic oscillator model, the one-dimensional hindered rotor model, and the mixing model. The results obtained were compared with the data from the literature and simultaneously correlated to obtain a highly reliable thermodynamic description.

Graphical Abstract

中文翻译：

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烷基膦酸酯和烷基磷酸酯化合物的热物理性质

有机磷化合物有着广泛的应用；它们通常用作药物或杀虫剂或用于生产离子电池。然而，一些作为战争神经毒剂开发的有机磷化合物具有神经毒性，对生物体可能致命。根据文献检索，这些化合物的某些性质尚不清楚。热力学性质的知识和可靠数据的可用性是开发检测、处理和安全分析去污方法的基础。出于研究目的，经常使用称为模拟物的替代品，它们具有相似的分子结构和性质，但毒性较小。这项工作提出了四种有机磷神经毒剂模拟物的热力学研究：磷酸三甲酯、磷酸三乙酯、甲基膦酸二甲酯和甲基膦酸二乙酯。差示扫描量热计和 Tian-Calvet 型量热计分别用于分析它们的相行为并测量液体热容。蒸气压通过静态方法通过实验测定。使用 R1SM 方法计算理想气体热容，该方法结合了刚性转子谐振子模型、一维受阻转子模型和混合模型。将获得的结果与文献中的数据进行比较，同时关联以获得高度可靠的热力学描述。

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