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

Participants

Reaction Steps

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).

Provenance & Evidence