5-Ethoxycarbonyloxy-2-nitrobenzoic acid → 5-Hydroxy-2-nitrobenzoic acid

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Reaction Steps

5-Ethoxycarbonyloxy-2-nitrobenzoic acid (6.12 g) was dissolved in a solution of potassium hydroxide (3.2 g of 85% pure material) in water (10 ml) and heated under reflux for 2 hours, to cleave off the ethoxy-carbonyl residue and form the di-potassium salt of 3-carboxy-4-nitrophenol. The solution so prepared was mixed with toluene and distilled until the water had been removed. Dimethyl sulphoxide (50 ml) was added and the mixture distilled until the vapour temperature reached 190°. A further quantity (50 ml) of dimethyl sulphoxide (50 ml) was then added, together with 3-chloro-4,5-difluorobenzotrifluoride (5.43 g), and the mixture heated at 100° for 4 hours. The mixture was diluted with water (200 ml) and acidified with dilute hydrochloric acid. The mixture was extracted twice with ether and the extracts washed with water, dried and evaporated. The brown oil remaining was crystallised from carbon tetrachloride to give the required compound (2 g) with a melting point of 145°-148°.

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