Resorcinol → 2-(2,4-Dihydroxybenzoyl)benzoic acid

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Reaction Steps

2′-Carboxy-2,4-dihydroxybenzophenone was prepared according to literature procedures. Smith, G. A.; Metcalfe, J. C.; Clarke, S. D J. Chem. Soc. Perkin Trans 2. 1993, 1195. AlCl3 (28.00 g, 210 mmol) was added to a solution of phthalic anhydride (13.85 g, 93.5 mmol) and resorcinol (10.0 g, 90.8 mmol) in 225 ml nitrobenzene and purged with N2. After stirring overnight, the solution was poured into a vigorously stirred biphasic solution of 750 ml hexanes and 1.0 L 0.5 M aqueous HCl. The solution was allowed to stir for 2 h and the light tan precipitate that formed was filtered and washed with 200 ml aqueous 0.1 M HCl and 200 ml hexanes. The crude material was crystallized as light green plates from hot MeOH/H2O (9.90 g, 42%). 1H NMR (acetone-d6) δ 6.33 (1H, dd, J=9.0, 2.3 Hz), 6.39 (1H, d, J=2.3 Hz), 7.00 (1 H, d, J=9.0 Hz), 7.45 (1 H, d, J=7.5 Hz), 7.65-7.80 (2 H, m), 8.12 (1 H, d, J=6.7 Hz). FTIR (KBr, cm−1) 1693, 1627, 1594, 1568, 1521, 1490, 1444, 1356, 1284, 1267, 1228, 1187, 1154, 1123, 1083, 1022, 981, 967, 930, 852, 813, 784, 769, 736, 713, 697, 665, 624, 592, 535, 458.

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