Acid hydrolysis of 3-aryl-5-trinitromethyl-1,2,4-oxadiazoles

Abstract

of compound I or II, 50 ml of acetic acid, and 10 ml of water was refluxed for 1 h. The solution was evaporated, and the residue was subjected to column chromatography (10 250-mm column) on activated silica gel (Silicagel 100/400 m) using diethyl ether as eluent. We isolated 0.5 g (63%) of 5-hydroxy-3phenyl-1,2,4-oxadiazole (III), mp 203 C [3], or 0.6 g (68%) of 5-hydroxy-3-(4-tolyl)-1,2,4-oxadiazole (IV), mp 220 C [4]. Hydrolysis of 3-aryl-5-trinitromethyl-1,2,4-oxadiazoles I and II in hydrochloric acid. A mixture of 3 mmol of compound I or II, 30 ml of concentrated hydrochloric acid, and 10 ml of water was refluxed for 3 h. The solution was evaporated, and the residue was purified by column chromatography (see above) with benzene as eluent. We isolated 0.2 g (53%) of benzamide oxime (V), mp 78 80 C [5], or 0.3 g (61%) of 4-methylbenzamide oxime (VI), mp 147 C [6]. Hydrolysis of 3-aryl-5-hydroxy-1,2,4-oxadiazoles III and IV in hydrochloric acid. A mixture of 3 mmol of compound III or IV, 15 ml of concentrated hydrochloric acid, and 5 ml of water was refluxed for 2.5 h. The solution was evaporated, and the residue was purified by column chromatography (see above) with benzene as eluent. We isolated 0.15 g (35%) of Scheme 1.