一种3-羟基-2,6-二烷基类吡啶合成方法的优化

通过改变催化剂及投料比来优化3-羟基-2,6-二烷基类吡啶的合成路线。结果表明：合成酰基呋喃的傅-克反应中以质量分数2%的三氟化硼乙醚稀溶液替代磷酸做催化剂，呋喃聚合类副产物少，产率达到70%以上；制备标题产物的开环-闭环反应中可加入适量铵盐晶体做催化剂，且该类铵盐晶体以氯化铵最为理想，其与氨水摩尔投加比例为1.5∶1时摩尔收率可达65%以上。减少氯化铵投加量将其摩尔比例调整为0.2∶1时，摩尔收率降至61%，但增加了反应釜投料体积，每釜产量能提高约92%。同时考察了酰基呋喃侧链烷基取代基对反应的影响，并通过¹HNMR对相关产物进行了表征。

An improved process for the synthesis of 3-hydroxy-2, 6-dialkyl pyridines

By changing the catalyst and improving the synthesis route, the necessary condit ions to obtain the title products in good yield have been established. Using 2% boron trifluoride etherate instead of phosphoric acid in the acylation reaction resulted in yields of 2-acyl-5-alkylfuran of over 70%, The acylfuran was eas ily converted to the title products by adding an appropriate amount of an ammoni um salt. Of the ammonium salts employed, ammonium chloride was found to give the best results, and when the feed ratio of ammonium chloride to ammonia was 1.5 ∶1, the yield exceeded 65%. In practice however, the ratio 0.2∶1 is the best value in terms of maximizing the output by making optimum use of the reactor vo lume and production reached about 92% per kettle. The structure of the final pro ducts was confirmed by ¹HNMR. 