5-(2-Furyl)-1,3,4-Oxadiazole-2-Thiol

Abstract

2-Furoic Acid Hydrazide. A mixture of 37.8 g (0.3 mole) of methyl 2-furoate (see Vol. 1 of this work, p. 27), b.p. 181°/760 mm, and 25 g (about 0.4 mole) of 85% hydrazine hydrate was prepared in a 250-ml round-bottomed flask fitted with an air condenser. The mixture was heated in a boiling water bath for six hours and was poured while still hot into a porcelain dish; it was stirred with a glass rod while being evaporated down on a sand bath (Note 1). Soon after evaporation began white fumes appeared; evaporation was continued until the liquid acquired the consistency of a thick sirup when cooled to room temperature (30–40 minutes), and the mixture was then, set aside to crystallize (Note 2). On the next day the completely solidified product was ground and dried in the air; 34–35 g of crude product was obtained as a colorless crystalline substance. It was purified by vacuum distillation (Note 3). 2-Furoic acid hydrazide came over at 146–148°/3 mm as a colorless liquid which solidified immediately in the receiver; m.p. 74–76°. Yield 27.0–28.0 g (71.4–74.1%) (Note 4).