申请人:Imperial Chemical Industries PLC
公开号:US04612377A1
公开(公告)日:1986-09-16
A 2-oxo-5-methyl-5,6-dihalopiperidine is contacted in a high boiling solvent, preferably trichlorobenzene, with a stoichiometric excess, up to 70 mole % excess, of a chlorinating agent, preferably phosphorus oxychloride or phosgene, at an elevated temperature between 80.degree. and 130.degree. C. The solution of 2-chloro-5-methylpyridine so obtained may be used directly for further chlorination to form 2-chloro-5-trichloromethylpyridine with, for example, chlorine gas in the presence of a free radical initiator. This chemical intermediate is useful in the synthesis of certain herbicidal compounds.
在高沸点溶剂中,最好使用三氯苯,将2-氧代-5-甲基-5,6-二卤代哌啶与氯化剂反应,反应物的量应超过化学计量量,高达70摩尔%的过量,最好使用氧化亚磷或光气,反应温度在80℃至130℃之间。所得的2-氯-5-甲基吡啶溶液可以直接用于进一步氯化反应,例如,在自由基引发剂的存在下,与氯气反应生成2-氯-5-三氯甲基吡啶。这种化学中间体在合成某些除草剂化合物中很有用。