Cyanogen Bromide → 4-Phenyl-3-thiocyanato-1,2,5-thiadiazole

Participants

Reaction Steps

To a stirred solution of 3.8 grams(g)(0.05 mole) of sodium sulfide in 100 mL of dimethylformamide was added 8 g(0.041 mole) of 4-Phenyl-3-chloro-1,2,5-thiadiazole. The mixture was stirred overnight (~16 hours), and to the resulting dark green solution was added 6.64 g(1.5 molar equivalents) of cyanogen bromide. This mixture was stirred for about 14 hours and then diluted with 100 mL of water and extracted with 200 mL of methylene chloride. The organic layer was separated and washed with water (2×100 mL), dried and concentrated under reduced pressure. The thus recovered crude material was chromatographed on silica gel with a 10% EtoAc:90% hexane mixture to yield 6.6 g (72 percent of theoretical) as an oil which turned to a white solid melting at 49° C. upon standing; 13C NMR (75 MHz, CDCl3) δ 159.10, 141.78, 130.59, 129.76, 129.06, 127.88, 105.98; MS (EI) m/e 219(M+), 192, 160, 135, 103.

Provenance & Evidence