Hydrochloric Acid → 2-Chloro-5-phenyl-1,3,4-thiadiazole

Participants

Reaction Conditions

Reaction Steps

A stirred suspension of 2-amino-5-phenyl-[1,3,4]thiadiazole (6.45 g, 36.4 mmol; Aldrich) and copper (230 mg, 3.6 mmol; Aldrich) in hydrochloric acid (36 mL, 12 M) and glacial acetic acid (180 mL) was chilled to 0° C. and treated with a solution of sodium nitrite (2.64 g, 38.2 mmol; Aldrich) in water (12 mL), added dropwise over 40 minutes. After stirring at room temperature for 4 hours, the mixture was poured into ice water. The aqueous solution was extracted with chloroform (3×), and the combined extracts were washed sequentially with 5% sodium bicarbonate and brine, and dried over sodium sulfate. The crude product was filtered through a short silica gel plug with chloroform to afford the title product: 1H NMR (300 MHz, CDCl3) δ ppm 7.46-7.55 (m, 3H), 7.85-7.93 (m, 2H). MS (DCI/NH3) m/e 197/199 (M+H)+.

Provenance & Evidence