4-Chlororesorcinol → 2-(5-Chloro-2,4-dihydroxybenzoyl)benzoic acid

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Reaction Steps

AlCl3 (40.0 g, 300 mmol) was added to a solution of phthalic anhydride (20.0 g, 135 mmol) and 4-chlororesorcinol (18.8 g, 130 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 300 ml hexanes. The crude product was crystallized from hot MeOH/H2O (12.1 g, 32%). 1H NMR (CD3OD) δ 6.48 (1H, s), 6.95 (1H, s), 7.39 (1H, dd, J=7.2 1.5), 7.62–7.52 (2H, m), 8.12 (1H, dd, J=1.2, 7.8).

Provenance & Evidence