Acetic Anhydride → 3-Hydroxy-5-nitro-4-phenylbenzoic acid

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Reaction Steps

5-Carboxy-3-nitro-2phenylbenzenediazonium tetrafluoroborate (110 g ) is added in portions to a stirred and refluxing mixture of acetic anhydride (275 ml) and acetic acid (275 ml). The mixture is refluxed for a further 4-5 hours and is then poured into ice-water (about 4 liters). The mixture is left for 20 hours, and the precipitated crude 3-acetoxy-5-nitro-4-phenylbenzoic acid is collected by filtration, washed with water and dried. It is saponified by heating with 4 N sodium hydroxide (250 ml) for 30 minutes; the resulting solution is left at 5° C for about 20 hours and is then filtered. The filtrate is acidified with 4 N hydrochloric acid to precipitate 3-hydroxy-5-nitro-4-phenylbenzoic acid. It is collected by filtration, washed with water and dried. After recrystallization from aqueous methanol, the acid is obtained with a melting point of 213°-215° C.

Provenance & Evidence