Ammonia → 3-Bromothiophene-2-carboxamide

Participants

Reaction Conditions

Reaction Steps

3-Bromothiophene-2-carboxylic acid (63.61 g, 307.2 mmol) was weighed into a 1 L round bottom flask equipped with reflux condenser and the flask was purged with argon. To this flask was added toluene (636.1 mL, 5972 mmol) and thionyl chloride (44.82 mL, 614.4 mmol) at room temperature, and the resulting mixture was stirred for 3 h at 100° C. The reaction mixture was evaporated and the residue was azeotroped with toluene (2×100 mL). The resulting residue was dissolved in tetrahydrofuran (954.1 mL, 11760 mmol) then 10 M ammonia in water (170 mL, 2500 mmol) was added slowly into the solution. The mixture was stirred for 5 h at room temperature. Thin-layer chromatography showed complete reaction. The reaction mixture was rotovaped to remove THF and the solid residue in water was filtered through a glass frit funnel then washed with water and dried under vacuum to give 3-bromothiophene-2-carboxamide as a white solid (33.26 g, 52.5%). LCMS: (FA) ES+ 206.0, 208.0

Provenance & Evidence