2-Amino-4,5-dimethoxybenzoic acid

4998-07-6

5653-40-7

General procedure for the synthesis of 2-amino-4,5-dimethoxybenzoic acid from 6-nitroveratric acid: first, 48.13 g (0.729 mol) of KOH pellets (85% purity) were dissolved in 250 ml of ice water. Subsequently, 50 g (0.207 mol) of methyl-4,5-dimethoxy-2-nitrobenzoate (1) was added to this clarified solution, and the resulting green suspension was heated to 70 °C. During heating, the color of the solution shifted to dark red. The progress of the reaction was monitored by HPLC and upon completion of the reaction, the solution was cooled to room temperature and the pH was adjusted to 6.6 with 34.6 g (0.570 mol) of glacial acetic acid.The obtained red suspension was hydrogenated at 50 °C and 3.5 bar pressure using 1 g of 10% Pd/C catalyst until the reaction was terminated. Upon completion of hydrogenation, the solution was filtered and the pH was adjusted to 5.1 with 31.82 g (0.525 mol) of glacial acetic acid under the protection of an inert gas.The light green suspension formed was stirred at room temperature for 30 min, followed by cooling to 5 °C and continued stirring for 30 min. The product (2) was obtained by filtration, washed in two batches with a total of 250 ml of ice water and finally dried in a vacuum oven at 55°C for 12 hrs. This process yielded 35.18 g (0.173 mol, 83% yield) of light gray crystalline product.