Nitric Acid → 2-Bromo-5-nitrothiophene

Participants

Reaction Steps

Nitric acid (24.00 g, 1.42 sp gr, 0.381 mol) in acetic anhydride (50 ml) at 0° C. was added dropwise to a cooled (0° C.) rapidly stirred solution of the compound of step 5.1 (24.77 g, 0.152 mol) in acetic anhydride (50 ml). At the end of the addition the stirring was continued for 0.5 hr and the mixture was refrigerated overnight. The mixture was poured into ice water (400 ml) and the precipitate was filtered off, dissolved in ether (2×200 ml), and washed with water until free of acid. The solvent was removed in vacuo and the residue was purified by column chromatography [silica gel/petroleum fraction (bp 40°-60° C.), dichloromethane, 5:1] and was recrystallised from ethanol/dimethoxyethane, 100:1 to give a pale yellow solid which was dried in vacuo (P2O5) to give 66% yield of 20.89 g.

Provenance & Evidence