2-氯-5-三氟甲基吡啶的合成

Synthesis of 2-Chloro-5-trifluoromethylpyridine

合成了除草剂吡氟禾草灵的中间体2-氯-5-三氟甲基吡啶,研究了影响反应的条件。结果表明,采用氧化汞或氟化汞作氟化催化剂、氟化氢作溶剂较好,适宜的反应温度为-20～-10℃,较长的反应时间(48h)和增加氟化氢和催化剂的量有利于氟化。2-氯-5-三氯甲基吡啶的转化率和选择率均可达到97%以上。反应后的滤渣可再生为氧化汞循环使用,回收3次,反应的转化率和选择率均大于85%。

2-chloro-5-trifluoromethylpyridine is an important intermediate of the herbicide fluazifop-butyl. Reaction conditions are studied, and the result shows that it is better to adopt mercuric oxide or mercuric fluoride as fluorination catalyst with reaction temperature -20～-10 ℃. Longer reaction time (48 h) and increase of hydrogen fluoride and catalyst are good for fluorination. Conversion and selectivity of 2-chloro-5-trichloromethylpyridine are both over 97%. Residues, regenerated as mercuric oxide, can be recycled. After the fluorination catalyst was recycled uesed three times, conversion and selectivity are still over 85%.