Nitric Acid → 4-Nitrothiophene-2-carboxylic acid

Participants

Reaction Steps

Sulfuric acid (3.0 mL, 5.505 g, 56.17 mmol) was added to nitric acid (2.0 mL, 2.98 g, 49.6 mmol) slowly at 0-10° C. After completion of the addition, thiophene-2-carboxylic acid (2.8 g, 21.87 mmol) was added to the above nitration mixture slowly for 15 min at the same temperature and stirred the mixture for 1 h. The reaction mixture was poured into ice cold water and stirred for 30 min. The precipitated solid was filtered, washed with cold water and dried. The filtrate was extracted with ethyl acetate. The combined ethyl acetate layer was washed with water, brine and dried over sodium sulfate. The solution was filtered and evaporated the solvent. The combined product was stirred with hexane (2×50 mL) and filtered the solid and dried to give the product as an off-white solid (2.8 g, 75%), mp 110-118° C. The product was a mixture of two compounds by HPLC and 1H NMR and was proceeded to the next step.

Provenance & Evidence