Bromine → 5-Bromo-3-methylthiophene-2-carbaldehyde

Participants

Reaction Steps

Bromine (104 mL, 2.02 mol) was added dropwise to a 0° C. solution of 255 g of 3-methylthiophene-2-carboxaldehyde (2.02 mol) in 1.7 L of chloroform cooled with an external ice bath. After the addition was complete, the mixture was allowed to slowly warm to room temperature, and then heated at reflux temperature for 2 hours. The red mixture was diluted with 1 L methylene chloride and successively washed with water, saturated bicarbonate solution, and brine. The organic fraction was dried over anhydrous sodium sulfate and concentrated to a red oil. The crude oil was then vacuum distilled to isolate fractions which eluted at 101-106° C. at ca. 2 torr, which produced 301 g of a pale yellow-green solid. 1H NMR (CDCl3, 200 MHz): δ=9.87 (s, 1H), 6.94 (s, 1H) 2.53 (s, 3H).

Provenance & Evidence