Ethanol → 3,3'-Dibromo-2,2'-bithiophene

A mixture of 3,3′,5,5′-tetrabromo-2,2′-bithiophene (25 g, 52.3 mmol), ethanol (50 ml), water (50 ml) and glacial acetic acid (100 ml) was heated to reflux. Then the heating oil bath was removed, and zinc powder (13.1 g, 200 mmol) was added in portions at such a rate that the mixture continued to reflux. After the addition was complete, heating was continued, the mixture was refluxed for another 5 h and cooled down to room temperature. The unreacted zinc powder was filtered off and the filtrate was collected, diluted with diethyl ether and then washed twice with water. The ether solution was dried with anhydrous MgSO4 and the solvent was evaporated under reduced pressure. The crude product was recrystallized from hexane to afford a greenish crystal in the yield of 91% (15.3 g). 1H-NMR (CDCl3, ppm): δ7.40 (d, 2H, J=5 Hz), 7.11 (d, 2H, J=5 Hz).

1. temperaturewas heated to reflux
2. customThen the heating oil bath was removed
3. temperatureto reflux
4. additionAfter the addition
5. temperatureheating
6. temperaturethe mixture was refluxed for another 5 h
7. filtrationThe unreacted zinc powder was filtered off
8. customthe filtrate was collected
9. additiondiluted with diethyl ether
10. washwashed twice with water
11. dry with materialThe ether solution was dried with anhydrous MgSO4
12. customthe solvent was evaporated under reduced pressure
13. customThe crude product was recrystallized from hexane
14. customto afford a greenish crystal in the yield of 91% (15.3 g)

ORD-Eintrag

ord-3a133bd736e64b00bc1205e759b0c891

Quelldatensatz

uspto-grants-2009_03

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07507840B2