Nitric Acid → 5-nitrothiophene-3-carboxylic acid

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Reaction Steps

3-Thiophenecarboxylic acid (5.12 g) was added portionwise to a mixture of nitric acid (20 ml) and sulfuric acid (11.5 ml) below 5° C. The mixture was stirred at the same temperature for 30 minutes, and poured into ice water. The mixture was alkalified with 1N sodium hydroxide and washed with diethyl ether. The aqueous layer was acidified with 1N hydrochloric acid and extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was recrystallized from ethyl acetate to give 5-nitro-3-thiophenecarboxylic acid (4.45 g) as crystals.

Provenance & Evidence