2-Bromothiophene → 5-Bromothiophene-2-sulfonyl chloride

Chlorosulfonic acid was added dropwise over 20 min. to a cold solution (−78° C.) of 2-bromothiophene (16.3 g, 100 mmol) in methylene chloride (50 ml) was added. After addition of chlorosulfonic acid was complete, the cold bath was removed. The reaction mixture was allowed to attain room temperature slowly (2 h), was added dropwise onto the crushed ice (1000 g) and was extracted with methylene chloride (4×100 ml). The combined organic layers was dried over MgSO4, filtered and the solvent was removed under reduced pressure to give a crude product. This was purified by column chromatography using hexane as eluent to give 5-bromothiophene-2-sulfonyl chloride (22 g, 75% yield).

1. additionwas added
2. customthe cold bath was removed
3. customto attain room temperature
4. customslowly (2 h)
5. additionwas added dropwise onto the crushed ice (1000 g)
6. extractionwas extracted with methylene chloride (4×100 ml)
7. dry with materialThe combined organic layers was dried over MgSO4
8. filtrationfiltered
9. customthe solvent was removed under reduced pressure
10. customto give a crude product
11. customThis was purified by column chromatography

ORD record

ord-59f84c3a16254378ab50e34f20ba89b1

Source dataset

uspto-grants-2003_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06613804B2