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对丙酮气相合成3,5-二甲基苯酚的反应过程进行了热力学分析,根据产物分析结果和反应历程,将反应分为3个阶段:丙酮的羟醛缩合反应、丙酮和异丙叉丙酮的1,6-Michael加成反应和异佛尔酮芳构化反应;采用Benson基团贡献法估算了部分化合物的热力学参数,推导了3步反应的焓变、吉布斯自由能变和反应平衡常数与温度的关系.结果表明,在373~973 K温度范围内,3个反应均能自发进行,异丙叉丙酮生成异佛尔酮为放热反应,丙酮生成异丙叉丙酮为可逆反应,异佛尔酮生成3,5-二甲基苯酚的反应为不可逆反应.
According to the results of the product analysis and the reaction process, the reaction was divided into three stages: the aldol reaction of acetone, the reaction of acetone and isopropylidene acetone 1,6-Michael addition reaction and isophorone aromatization reaction. The Benson group contribution method was used to estimate the thermodynamic parameters of some compounds. The enthalpy change, Gibbs free energy change and reaction equilibrium of the three-step reaction were deduced. The results showed that all three reactions proceeded spontaneously in the temperature range from 373 to 973 K. The isophorone was formed by the reaction of isophorone with an exothermic reaction and the reaction with acetone as a generation of acetone was reversible. The reaction of isophorone to 3,5-dimethylphenol is irreversible.