Acetic Anhydride → 1H-1,2,4-Triazole, 1-acetyl-3-(p-chlorophenyl)-5-methyl-

Participants

Reaction Steps

63.6 g (254.0 mM) 4-Chloro-N-(3,5-dimethyl-4H-1,2,4-triazol-4-yl)benzenecarboximidamide prepared in part B and 67 ml of acetic anhydride in a 300 ml round bottom flask equipped with a distillation head are heated to 170° in an oil bath. A solution forms from which acetic acid distills off in the first few minutes. The mixture is refluxed for 2.5 hours and the excess acetic anhydride is evaporated to dryness under vacuum to produce a residue comprising a mixture of the title compound and its 1-acetyl-5-(4-chlorophenyl)-3-methyl isomer. The residue is triturated with 120 ml of water at room temperature and filtered. The filter cake is dissolved in 1 liter of hot ethanol, filtered hot, and the product precipitated from the hot alcohol by adding 3 liters of cold water. The product is filtered off, wshed with water, and dried at 80° under vacuum to yield 37.6 g of the 1-acetyl-3-(4-chlorophenyl)-5-methyl-1H-1,2,4-triazole as a crystalline material (99% pure), m.p. 132°-133°.

Provenance & Evidence