Nitric Acid → 4-Nitrothiophene-2-carboxylic acid

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.

1. additionwas added to the above nitration mixture slowly for 15 min at the same temperature
2. additionThe reaction mixture was poured into ice cold water
3. stirringstirred for 30 min
4. filtrationThe precipitated solid was filtered
5. washwashed with cold water
6. customdried
7. extractionThe filtrate was extracted with ethyl acetate
8. washThe combined ethyl acetate layer was washed with water, brine
9. dry with materialdried over sodium sulfate
10. filtrationThe solution was filtered
11. customevaporated the solvent
12. stirringThe combined product was stirred with hexane (2×50 mL)
13. filtrationfiltered the solid
14. customdried

ORD record

ord-fcff23db83a04a1b84c2510255576fcb

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08258119B2