Synthesis
General procedure for the synthesis of 4-methoxy-2,3-dimethylbenzoic acid from 4-methoxy-2,3-dimethylbenzaldehyde: 60.0 g of 4-methoxy-2,3-dimethylbenzaldehyde was dissolved in 1.20 L of dimethyl sulfoxide. Subsequently, a solution prepared by dissolving 131.5 g of sodium dihydrogen phosphate and 132.2 g of sodium chlorite in 480 mL of water was added dropwise, during which the reaction temperature was controlled not to exceed 40 °C. After addition, the reaction mixture was continued to be stirred at room temperature for 2 hours. Upon completion of the reaction, the suspension was diluted with 2.0 L of water, the precipitate was collected by filtration, washed with water and dried under vacuum at 100 °C to afford 65.0 g of the target product 4-methoxy-2,3-dimethylbenzoic acid as a colorless solid with a melting point of 214 °C (MS: 181.2 [MH+]).
References
[1] Patent: US2011/60050, 2011, A1. Location in patent: Page/Page column 4
[2] Patent: US2011/224302, 2011, A1. Location in patent: Page/Page column 10; 15
[3] Bioorganic Chemistry, 1996, vol. 24, # 4, p. 386 - 400
[4] Patent: EP1666473, 2006, A1. Location in patent: Page/Page column 41
