1. 40 mL of dry o-xylene was rapidly added to a 250 mL PTFE-lined autoclave under argon protection. 2. 2.5 g of anhydrous aluminum trichloride (AlCl3) and 1.16 g of dry N-butylimidazole were added sequentially. Add 2.5 g of anhydrous aluminum trichloride (AlCl3) and 1.16 g of dry N-butylimidazole sequentially, and seal the reaction vessel after addition. 2. Connect a carbon dioxide cylinder to the autoclave through a pipeline, adjust the valve so that the CO2 pressure is maintained at 6 MPa, start the stirrer, and set the rotation speed at 1,000 rpm, and then begin to heat the system to 40°C, and the reaction lasts for 48 hours. 3. At the end of the reaction, 150 mL of water was added to the system and stirred for 30 min. 4. The reaction mixture was extracted three times with 50 mL of ether, and the organic phases were combined, concentrated and dried to give 2.76 g of an off-white solid, i.e., crude 2,3-dimethylbenzoic acid. 5. The above crude product was dissolved in 20 mL of a 10% (w/w) sodium hydroxide solution, and filtered to remove insoluble matter, to give a filtrate. 6. The filtrate was extracted with 1 mol/L hydrochloric acid to adjust the pH of the filtrate to 1 and let it stand at room temperature for 60 min. 7. The mixture was transferred to -10°C for further crystallization and filtered to obtain crystals. 8. The crystals were dried to obtain 2.29 g of white solid 2,3-dimethylbenzoic acid in 81.3% yield.
