4-Chlorobutyryl chloride → 5-(4-Chlorobutyramido)-4-cyano-1-(2,3,4-trichlorophenyl)pyrazole

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Reaction Steps

A mixture of 5-amino-4-cyano-1-(2,3,4-trichlorophenyl)pyrazole (12.47 g) and 4-chlorobutyryl chloride (12.3 g) in dry acetonitrile (200 ml) was stirred and gently warmed to effect dissolution. The solution was cooled to room temperature and stirred, after 48 hours a further quantity of 4-chlorobutyryl chloride (6.15 g) was added and stirring continued for 24 hours. The solution was evaporated under reduced pressure to give an oil which was chromatographed using dichloromethane-ethyl acetate (19:1) as eluent. Evaporation of the eluate containing the fastest moving component gave 5-(4-chlorobutyramido)-4-cyano-1-(2,3,4-trichlorophenyl)pyrazole (5 g), m.p. 173°-174° C., after crystallisation from toluene, in the form of pale yellow crystals.

Provenance & Evidence