3-Ethoxy-4-hydroxybenzaldehyde (50.0 g, 0.30 mol) and triethylamine (Et3N, 39.2 g, 54 mL, 0.39 mol) were dissolved in dichloromethane (DCM, 500 mL) at 0 °C. Acetyl chloride (CH3COCl, 30.6 g, 28 mL, 0.39 mol) was slowly added dropwise to this solution, maintaining the temperature at 0°C. After the dropwise addition was completed, the reaction mixture was continued to be stirred at 0 °C for 30 min. Upon completion of the reaction, the solid product was collected by filtration and the filter cake was washed with dichloromethane. All the filtrates were combined and washed sequentially with water and brine, and the organic layer was dried with anhydrous sodium sulfate (Na2SO4). Finally, the solvent was removed by evaporation to afford the target product 2-ethoxy-4-formylphenyl acetate (62.0 g, 100% yield) as a yellow solid.
