THERMOLYSIS OF 3-PHENYL-5-ARYLAMINO-1,2,4-OXADIAZOLE AND THIADIAZOLE DERIVATIVES

Thermal reactions of 3-phenyl-5-arylamino-1,2,4-oxadiazoles I and II w ere investigated. Neat heating at ca. 250 degrees C for 6 hours afford ed H2O, benzonitrile, arylcyanamides, arylamines, azobenzene, benzimid azole derivatives, and 3,3'-diphenyl-5,5'-bis[1,2,4-oxadiazolyl]. Anal ogous results weve obtained by the thermolysis of 3-phenyl-5-anilino-1 ,2,4-thiadiazole III at ca. 200 degrees C for 2 hours. In addition to H2S, NH3 and HNCS, phenyl isothiocyanate and thiocarbanilide were obta ined. Thermolysis of III in quinoline as a radical trap gave analogous results but also 2-anilinoquinoline. A free-radical mechanism has bee n suggested to account for the identified products. (C) 1997 John Wile y & Sons, Inc.