Sodium Carbonate → 5-Bromothiophene-2-carboxylic acid

Participants

Reaction Steps

5-Bromo-2-thiophenecarboxaldehyde (1.0 g;5.24 mmol) was dissolved in acetone (4 ml) and treated with 20% Na2CO3 (aq) (0.53 ml). KMnO4 (0.827;5.24 mmol) was added portionwise and the solution stirred for 1 hour at RT. The reaction mixture was filtered through kieselguhr and the filtrate treated with H2O2 (0.8 ml of a 27% solution in water). When all effervesence had ceased, the aqueous was acidified with conc.HCl(aq) and a yellow solid precipitated. The suspension was extracted with EtOAc, the extracts combined and dried over Na2SO4, filtered, and the filtrate evaporated in vacuo to a yellow liquid. The liquid was diluted with hexane and cooled to -78° C. The solid that formed was collected by filtration and dried to yield the title compound as a pale yellow solid (0.3 g;28%).

Provenance & Evidence