9,10-Dioxo-9,10-dihydroanthracene-1-carboxylic acid → 1-Anthracenecarboxylic Acid

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Reaction Steps

To a 5 L 3-neck flask fitted with condenser, thermometer, and overhead stirrer was added 9,10-dihydro-9,10-dioxo-1-anthracenecarboxylic acid (15A, 90 g, 0.357 mol), Zn dust (Mallinckrodt, 250 g, 3.82 mol), CuSO4.5H2O (Mallinckrodt, 5 g), and 28% NH4OH (Mallinckrodt, 2500 mL). The mixture was heated slowly. A dark-red solution occured as the temperature reched 85°. After 3.5 h, the color of the solution faded to yellow. The reaction was heated an additional 1 H, cooled and the excess Zn removed by filtration. The filter cake was washed with more NH4OH solution (100 mL) and then discarded. The filtrate was carefully acidified to pH 1 with conc. HCl (added in portions over 1 h) affording a light-green precipitate, which was separated by filtration. The solid was washed with H2O (200 mL) and then recrystallized 1× from methoxyethanol/H2O (containing 1% conc. HCl), filtered and dried at 75°, to give 65 g (82%) of 1-anthracenecarboxylic acid mp 249°-250°, (C, H), (lit. mp 245°, Chemistry of Carbon Compounds IIIb, edited by E. H. Rodd, 1373 (1956), Elsevier, New York).

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