Hydrogen Bromide → 2-Bromo-5-phenyl-1,3,4-thiadiazole

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Reaction Conditions

Reaction Steps

A mixture of 2-amino-5-phenyl-1,3,4-thiadiazole sulfate (Aldrich, 2.5 g, 9.08 mmol) and 48% aqueous HBr (10 mL) was cooled to 5° C. and a solution of NaNO2 (0.69 g, 9.99 mmol) H2O (10 mL) was added dropwise at a rate so the internal temperature is maintained at approximately 5° C. The mixture was stirred for 15 min after the addition, then CuBr (0.69 g, 4.8 mmol) was added portion-wise so as to maintain the temperature at approximately 5° C. After the addition was complete, the mixture was allowed to warm to ambient temperature and stirred for 16 h. The mixture was diluted with 20 mL CH2Cl2 and 10 mL H2O. The organic layer was separated and concentrated under reduced pressure to provide the title compound (1.63 g, 6.76 mmol, 74% yield). MS (DCl/NH3) m/z 241, 243 (M+H)+.

Provenance & Evidence