2-Bromo-4,5-methoxyphenylacetic acid can be obtained from 3,4-dimethoxyphenylacetic acid after bromination with bromin. 72g of 3,4-dimethoxyphenylacetic acid was dissolved in 600mL of glacial acetic acid, stirred at room temperature for 1h and then 7.2g of glacial acetic acid (60mL) solution of bromine was added, and the reaction was continued for 2h and then 200mL of ice water was added, a white precipitate was generated, filtered, and the filter cake was recrystallized with methanol to obtain 96g of the compound 2-bromo-4,5-methoxybenzeneacetic acid, with a yield of about 95%, as a white solid.
