2,3,4-Trimethoxybenzoic acid was used in the synthesis of tropoloisoquinoline alkaloid pareitropone. It was also used in the synthesis of isomeric tris(pyrogallol) derivatives and naphthoic acid.
General procedure for the synthesis of 2,3,4-trimethoxybenzoic acid from 2,3,4-trimethoxybenzaldehyde: To a stirred solution of 2,3,4-trimethoxybenzaldehyde (24.4 g, 124.4 mmol) in methanol (200 mL) was added an aqueous 50% potassium hydroxide solution (KOH, 22.4 g). The mixture was then heated to reflux. A 30% hydrogen peroxide solution (180 mL) was added dropwise over 30 minutes and the mixture was continued to reflux for 8 hours. After the oxidation reaction was complete, the reaction mixture was cooled and sodium bisulfite (NaHSO3) was added. Methanol was removed by distillation under reduced pressure and the resulting solution was acidified to acidity with concentrated hydrochloric acid. The precipitated 2,3,4-trimethoxybenzoic acid (25.0 g, 95% yield) was collected by filtration.
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