Acetic Acid → 3,3'-Dibromo-2,2'-bithiophene

3,3′,5,5′-Tetrabromo-2,2′-bithiophene 10 (12.5 g, 25.9 mmol) was added in portions within 0.5 h to a refluxing dispersion of Zn powder (6.5 g, 0.1 mol) in 130 mL of ethanol containing 13 mL of water, 31 mL of glacial acetic acid, and 2.6 mL of 3 M HCl. After heating under reflux for two additional hours and then cooling to room temperature, the mixture was filtered and washed three times with ethanol, and the filtrate was collected. The solvent was then removed by evaporation, and 60 mL of H2O was added. The mixture was then extracted with diethyl ether, and the combined extracts were washed with water, dried over anhydrous MgSO4, and filtered. The solvent was removed by evaporation, and the crude product was recrystallized from hexane to give colorless crystals (7.6 g, yield 90%). 1H NMR (CDCl3): 7.41 (d, J=5.3 Hz, 2H), 7.09 (d, J=5.3 Hz, 2H) ppm; 13C NMR (CDCl3): δ 112.84, 127.73, 129.07, 131.01 ppm.

1. temperatureAfter heating
2. temperatureunder reflux for two additional hours
3. filtrationthe mixture was filtered
4. washwashed three times with ethanol
5. customthe filtrate was collected
6. customThe solvent was then removed by evaporation, and 60 mL of H2O
7. additionwas added
8. extractionThe mixture was then extracted with diethyl ether
9. washthe combined extracts were washed with water
10. dry with materialdried over anhydrous MgSO4
11. filtrationfiltered
12. customThe solvent was removed by evaporation
13. customthe crude product was recrystallized from hexane

ORD record

ord-234b0eaa38354105be532046dac65228

Source dataset

uspto-grants-2010_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07816480B2