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以三氯乙酸甲酯与丙烯腈加成反应合成的2,2,4-三氯-4-氰基丁酸甲酯为原料,与三氯氧磷进行环化反应制备2,3,5,6-四氯吡啶(简称四氯吡啶)。当三氯氧磷与2,2,4-三氯-4-氰基丁酸甲酯的摩尔比为2∶1,反应温度为140℃,反应时间为4 h,四氯吡啶的收率最高,可达93%。用气相色谱/质谱联用仪、红外光谱仪、核磁共振波谱仪等对反应产物进行了分析表征。同时探讨了2,2,4-三氯-4-氰基丁酸甲酯环化反应合成2,3,5,6-四氯吡啶的机理。
Methyl 2,2,4-trichloro-4-cyanobutyrate synthesized by addition reaction of methyl trichloroacetate and acrylonitrile was used as raw material to prepare 2,3,5, 6-tetrachloropyridine (referred to as tetrachloropyridine). When the molar ratio of phosphorus oxychloride to methyl 2,2,4-trichloro-4-cyanobutyrate was 2:1, the reaction temperature was 140 ℃ and the reaction time was 4 h, the yield of tetrachloropyridine was the highest , Up to 93%. The reaction products were characterized by gas chromatography / mass spectrometry, infrared spectroscopy and nuclear magnetic resonance spectroscopy. The mechanism of cyclization of methyl 2,2,4-trichloro-4-cyanobutyrate to 2,3,5,6-tetrachloropyridine was also discussed.