Hydrochloric Acid → 2,4-dichloro-5-nitrobenzoic acid

Participants

Reaction Steps

2,4-Dichlorobenzoic acid 1-1 (1.0 g, 5.34 mmol) was added in one portion to a stirred solution of concentrated nitric acid (0.26 mL, 5.75 mmol) in concentrated sulphuric acid (7 mL). After 3 hours at room temperature the solution was poured onto ice. The resulting white solid was isolated via filtration and washed with H2O (×3). The white solid was then stirred with 1% Na2CO3 (aq) (20 mL) for 1 h at room temperature. Remaining insoluble material was filtered off and the resulting clear filtrate was concentrated to a pale yellow solid. Recrystallisation from H2O afforded the sodium salt as pale yellow crystals. (Note: the other minor product, sodium 2,4-dichloro-3-nitrobenzoate, remained in solution). The yellow crystals of sodium 2,4-dichloro-5-nitrobenzoate was dissolved in a minimum amount of H2O and acidified by the slow addition of concentrated HCl until a white precipitate formed. After isolation by filtration and washing with H2O 2,4-dichloro-5-nitrobenzoic acid 1-2 was obtained as a white solid (0.91 g, 72%). 1H NMR (400 MHz, CDCl3) δ7.73 (s, 1H), 8.60 (s, 1H).

Provenance & Evidence