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TCI Practical Example: Bromination Reaction Using N-Bromosuccinimide

We are proud to present the regioselective bromination reaction of 2-methylbenzo[b]thiophene by using N-bromosuccinimide (= NBS).

Used Chemicals

• 2-Methylbenzo[b]thiophene [M1429]
• N-Bromosuccinimide (= NBS) [B0656]
• Acetonitrile

Procedure

A solution of 2-methylbenzo[b]thiophene (500 mg, 3.4 mmol) in acetonitrile (5 mL) was stirred under nitrogen at 0 ˚C. Then NBS (630 mg, 3.5 mmol) was added the solution. The ice bath was removed and the mixture was stirred at room temperature for 30 minutes. The reaction mixture was quenched with water and extracted with dichloromethane. The organic layer was dried over anhydrous sodium sulfate and filtered. The solvent was removed under reduced pressure and the crude was purified by silica gel column chromatography (hexane, Rf = 0.65) to give 3-bromo-2-methylbenzo[b]thiophene as a white solid (759 mg, 99% yield).

Experimenter’s Comments

The reaction mixture was monitored by TLC (hexane, Rf = 0.65).

Analytical Data

3-bromo-2-methylbenzo[b]thiophene

¹H NMR (270 MHz, CDCl₃); δ 7.70-7.75 (m, 2H), 7.30-7.44 (m, 2H), 2.56 (s, 3H).

Lead Reference

• Reactive ligand influence on initiation in phenylene catalyst-transfer polymerization
• • A. O. Hall, S. R. Lee, A. N. Bootsma, J. W. G. Bloom, S. E. Wheeler, A. J. McNeil, Polym. Chem. 2017, 55, 1530.