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采用密度泛函理论,使用Materials Studio的DMol3模块,计算了1,1,1,3,3-五氯丙烷(HCC-240fa)气相氟化生成1,3,3,3-四氟丙烯(HFO-1234ze)反应体系中各反应的反应焓变和Gibbs自由能变;并通过比较不同温度下各反应的反应焓变和Gibbs自由能变,对反应过程进行了热力学分析.结果表明:HCC-240fa经过氟氯交换和脱HCl反应合成中间体1-氯-3,3,3-三氟丙烯(HCFC-1233zd)的反应为热力学上可自发进行的反应,且产物以HCFC-1233zd(E)为主;低温有利于HCFC-1233zd与HF进行加成反应生成1-氯-1,3,3,3-四氟丙烷(HFC-244fa),HFC-244fa可与HF进行氟氯交换反应合成1,1,1,3,3-五氟丙烷(HFC-245fa);高温有利于HCFC-1233zd进行氟氯交换反应合成HFO-1234ze;HFC-244fa脱HCl反应和HFC-245fa脱HF反应均需要较高的反应温度,主产物为HFO-1234ze(E).
Density functional theory (DFT) was used to calculate the gas phase fluorination of 1,1,1,3,3-pentachloropropane (HCC-240fa) to 1,3,3,3-tetrafluoropropene (HFO -1234ze), and the Gibbs free energy change of each reaction in the reaction system. Thermodynamic analysis of the reaction process was carried out by comparing the reaction enthalpy change and Gibbs free energy change of each reaction at different temperatures. The results showed that: HCC-240fa The reaction of the synthesis of 1-chloro-3,3,3-trifluoropropene (HCFC-1233zd) via the chlorofluorocarbon exchange and the dehydrochlorination reaction is a thermodynamically spontaneous reaction and the product is represented by HCFC-1233zd Lord; low temperature is conducive to HCFC-1233zd and HF for the addition reaction of 1-chloro-1,3,3,3-tetrafluoropropane (HFC-244fa), HFC-244fa with HF fluoride exchange reaction 1, 1,1,3,3-pentafluoropropane (HFC-245fa); high temperature is conducive to the synthesis of HFO-1234ze by chlorofluorocarbon exchange reaction of HCFC-1233zd; both HFC-244fa deacidification reaction and HFC- The main product is HFO-1234ze (E).