2-Phenylacetophenone → 4,5-Diphenyl-1,2,3-thiadiazole

Participants

Reaction Steps

The tosylhydrazone (58.0 g, 0.16 mol) was dissolved in CH2Cl2 (200 ml) and thionyl chloride (14.1 ml, 0.2 mol) in CH2Cl2 (10 ml) was added and the entire reaction was stirred at room temperature 2.25 hours. Filtration of the mixture afforded 9.0 g of solid identified by NMR as toluenesulfonylchloride. The remaining liquid was concentrated and then heated at reflux in THF (200 ml) and H2O (50 ml) for 20.5 hours. After cooling, it was brought to pH 11 with NaOH. The aqueous layer was extracted with 2×50 ml portions of Et2O. Drying and evaporation yielded 34 g of solid material. This was recrystallized from hexane to afford 3 (7.5 g, 46%), m.p. 92°-94° C. A second crop from recrystallization afforded additional amounts of 3 (6.9 g) contaminated with a-phenylacetophenone. The thiadiazole could be sublimed at 110° C. (0.2 mm).

Provenance & Evidence