2-氯吡啶的合成研究

以吡啶为原料,用两步法(先用过氧化氢将吡啶氧化成氧化吡啶,再与三氯氧磷反应)、光氯化法(在紫外光的照射下,吡啶与氯气反应)和高温氯化法(在290℃的高温下,吡啶与氯气反应)三种方法合成2-氯吡啶,研究了溶剂与吡啶的摩尔比、反应时间等对产率的影响。结果表明:两步合成法总产率不高,约20%~25%;直接光氯化法和高温氯化法产率较高,尤其前者,通过3次反应,产率可达到80%以上。

Study on synthesis of 2-chloropyridine

2-Chloropyridine were synthesized from pyridine by three ways.Two-step synthesis way——pyridine was oxidated by H_2O_2,then the obtained pyridin-N-oxide was reacted with phosphorus oxychloride and 2-chloropyridine were synthesized;chloridization by light——2-chloropyridine were synthesized by the reaction of pyridine and chlorine under ultraviolet radiation;chloridization by high temperature——2-chloropyridine were synthesized by the reaction of pyridine and chlorine under 290℃.Effect factors such as the mole ratio of solvent to pyridine,reaction time on yield were discussed in this paper.By the comparison of these ways,it could be concluded that: ① the yield of two-steps synthesis way is the lowest,about 20%~25%;② the yields of chloridization by light and chloridization by high temperature are higher,especially the former,the yield could be 80% by cycling reaction.