棕榈酸异丙酯合成反应的热力学分析

摘要

Thermodynamics of isopropyl palmitate synthesis via a two-step noncatalytic method including acylation and alcoholysis reactions was studied. The thermophysical properties of palmitic acid, palmitoyl chloride and isopropyl palmitate were calculated by Tyagi equation, Joback method and Yoneda method.θrm∆H,θrm∆S,θrm∆G, andKθwere estimated and these data were analyzed at different temperatures. The results show that the acylation reaction is endothermic and difficult to achieve separately under standard conditions, while the alcoholysis reaction is exothermic and can be fully preceded separately. Considering the thermodynamics of the whole two-step reaction, the acylation reaction can happen following the approximate principle and Le Chatelier′s Principle.%针对“两步法”合成棕榈酸异丙酯反应体系，采用Joback基团贡献法、Yoneda基团贡献法及Tyagi方程估算了相关物质的热力学数据，并结合有关文献，计算得到了该反应体系的反应焓变θr m∆ H 、反应熵变θrm∆S 、反应吉布斯自由能变θrm∆G 及反应平衡常数Kθ。通过分析该反应热力学性质，结合两步反应的θrm∆G 数值特点，得到一定条件下酰氯化为吸热反应，单独存在时较难进行，醇解为放热反应，且反应可进行完全。由于两步反应是耦合的，依据近似原则和勒夏特列平衡移动原理，酰氯化反应在适当条件下可正常进行，且反应过程中可促使平衡向正向移动，有助于反应进行完全。