Ammonium Hydroxide → 2-Bromo-5-methoxy-3-methylbenzoic acid

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Reaction Conditions

Reaction Steps

A solution of (2-bromo-5-methoxy-3-methyl-phenyl)-methanol ((Example 192: step c) 7.85 g, 34.0 mmol) in acetone (300 mL) was heated to 60° C. and treated over 25 min. with KMnO4 (12.6 g, 79.8 mmol) as an aqueous solution (175 mL). The mixture was heated to 60° C. for an additional 35 min. A saturated aqueous solution of NaHSO3 was added until the solution turned beige in color. Concentrated NH4OH was added to pH 10 and the solids were filtered through a medium porosity fritted funnel. The filtrate was acidified to pH 4 with concentrated HCl, and the solution was extracted with ether (2×200 mL). The combined organic layers were dried over MgSO4 and concentrated in vacuo to afford the product 2-bromo-5-methoxy-3-methyl-benzoic acid (4.15 g, 50%) as a white solid. 1H NMR (MeOD): δ 6.968 (d, 1H, J=2.8 Hz), 6.775 (d, 1H, J=3.2 Hz), 3.776 (s, 3H), 2.352 (s, 3H).

Provenance & Evidence