Hydrochloric Acid → 4-Methoxyphthalic acid

Participants

Reaction Steps

To a solution of 4-hydroxyphthalic acid (0.25 g, 1.37 mmol) in anhydrous N,N-dimethylformamide (3 ml) under nitrogen was added sodium hydride (0.22 g, 5.48 mmol). The solution was stirred for 5 minutes and then methyl iodide (0.68 ml) was added and continued stirring for 3 hours. Several drops of water were added to quench the reaction and the mixture was concentrated in vacuo. The crude material was partitioned between ethyl acetate (40 ml) and water (10 ml). The layers were separated and the organic layer washed with brine (2×10 ml), dried (Na2SO4), filtered and the solvent evaporated in vacuo. The resulting oil was dissolved in methanol (8 ml) and 1N sodium hydroxide (4 ml) was added. The reaction was stirred at ambient temperature for 24 h., after which LC-MS indicated only partial hydrolysis. The material was reconstituted in methanol (5 ml) and treated with of sodium hydroxide (0.12 g, 3.0 mmol) dissolved in water (1 ml). The reaction mixture was stirred for 48 h., at which time a precipitate had formed. The mixture was acidified with 6N hydrochloric acid until pH=1, causing the solution to become homogeneous. The reaction was concentrated in vacuo and the residue partitioned between ethyl acetate (30 ml) and 0.5N hydrochloric acid (10 ml). The layers were separated and the organic layer concentrated in vacuo to give 100 mg (51%) of 4-methoxy-phthalic acid as a solid.

Provenance & Evidence