Nitric Acid → 5-Methyl-4-nitrothiophene-2-carboxylic acid
Reaction equation
[N+:1]([O-:4])(O)=[O:2].C(OC(=O)C)(=O)C.[CH3:12][C:13]1[S:17][C:16]([C:18]([OH:20])=[O:19])=[CH:15][CH:14]=1>>[CH3:12][C:13]1[S:17][C:16]([C:18]([OH:20])=[O:19])=[CH:15][C:14]=1[N+:1]([O-:4])=[O:2]Participants
4
Conditions
- Temperature
- -78 °C
Procedure
Under N2, fuming nitric acid (4.7 mL, 112.0 mmol) was added slowly over 10 min to acetic anhydride (16.6 mL, 175.6 mmol) cooled in a dry ice/acetone bath to −78° C. 5-methyl-2-thiophene carboxylic acid (5.0 g, 35.2 mmol) was added in 1 g portions over 10 min to the solution. The reaction was kept at −20° C. for 1 h before quenching over ice. The yellow solid was filtered off and washed with water (200 mL). The crude product was recrystallized from 95% EtOH to give 5-methyl-4-nitro-2-thiophene carboxylic acid as a pale yellow solid (4.6 g, 70%). 1H NMR (400 MHz, CD3OD) δ (ppm) 8.13 (s, 1H) 2.82 (s, 3H).
Workup
- custombefore quenching over ice
- filtrationThe yellow solid was filtered off
- washwashed with water (200 mL)
- customThe crude product was recrystallized from 95% EtOH
Sources & evidence
- ORD record
- ord-37c9d3f3bbca4700916dad9c3c91c8d5
- Source dataset
- uspto-grants-2011_02
- Patent number
- US07884124B2
Reaction notes
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