Nitric Acid → Mono nitro-benzo[b]thiophene-2-sulfonyl chloride

Participants

Reaction Steps

To a solution of benzo[b]thiophene-2-sulfonyl chloride (1.165 g, 5 mmol) in 25 mL of dichloromethane was added 3.6 mL of concentrated nitric acid (>22.05 mol/L) dropwise, the resulting mixture was refluxed overnight and cooled to room temperature before it was poured into 20 gram of crushed ice. The organic layer was separated and the aqueous layer was extracted by 220 mL 2 dichloromethane. The organic layers were combined and dried over MgSO4. Solvent was then removed by rotary evaporator. The crude product was purified by flash column chromatography with an eluent of hexane, followed by a gradient eluent of hexane/ethyl acetate (6/1-3/1) to afford 0.58 g of product (mixture of 65% of 4-nitro-benzo[b]thiophene-2-sulfonyl chloride and 35% of 7-nitro-benzo[b]thiophene-2-sulfonyl chloride).

Provenance & Evidence