The reaction system was cooled to -5 to 0 °C under nitrogen protection using 1,3,5-trimethoxybenzene (40 g, 0.22 mol) and N,N-dimethylformamide. Subsequently, phosphoryl chloride (48 g, 0.5 mol) was slowly added dropwise over 30 to 45 minutes. After the dropwise addition was completed, the reaction mixture was kept at 0 °C and stirring was continued for 1 hour. Upon completion of the reaction, the mixture was poured onto crushed ice and neutralized with saturated sodium carbonate solution. The precipitate precipitated was collected by filtration and washed with distilled water to give the final 2,4,6-trimethoxybenzaldehyde. Yield: 46 g (98% yield); 1H NMR (CDCl3): δ 10.35 (s, 1H), 6.67 (s, 2H), 3.88 (s, 6H), 3.87 (s, 3H); Mass Spectrum (MS): m/e 197 (M + 1).
