An extensive thermodynamic study of acetamide and its derivatives, N-methylacetamide, and N,N-dimethylacetamide, is presented in this work. Phase behavior was investigated by a heat-flux differential scanning calorimetry (DSC) from 183 K confirming the previously reported polymorphism of acetamide and N-methylacetamide. Two different polymorphic forms of N,N-dimethylacetamide were observed for the first time. Two static apparatus were employed for the vapor pressure measurements over a wide temperature range focusing on the ambient temperatures. Vapor pressures of metastable phase of acetamide were determined for the first time. Heat capacities of liquid and crystalline phases were measured by Tian-Calvet calorimetry at temperatures between 265 and 355 K. The ideal-gas thermodynamic properties were calculated using a combination of the density functional theory (DFT) and statistical thermodynamics. A consistent thermodynamic description was developed using the method of simultaneous correlation, where the experimental data for phase behavior, vapor pressures, and condensed phase heat capacities and calculated ideal-gas heat capacities are treated together to ensure overall thermodynamic consistency of the results. The observed trends in the thermodynamic properties of liquid phase were rationalized based on molecular interactions.

在这项工作中，对乙酰胺及其衍生物N-甲基乙酰胺和N，N-二甲基乙酰胺进行了广泛的热力学研究。通过热通量差示扫描量热法（DSC）从183 K研究了相行为，证实了先前报道的乙酰胺和N-甲基乙酰胺的多态性。N，N的两种不同的多态形式首次观察到-二甲基乙酰胺。在静态温度范围内，采用两个静态仪器进行蒸气压测量。首次确定了乙酰胺亚稳相的蒸气压。通过Tian-Calvet量热法在265至355 K之间的温度下测量了液相和结晶相的热容量。结合密度泛函理论（DFT）和统计热力学计算了理想气体的热力学性质。使用同时相关的方法开发了一致的热力学描述，其中的相行为，蒸气压，冷凝相的热容和计算出的理想气体热容应一起处理，以确保结果的总体热力学一致性。基于分子相互作用，合理地观察到了液相热力学性质的趋势。