1. To a 250 mL round bottom flask, add 10 g of 1-methylimidazole and immerse the flask in an ice bath. Slowly add 10 mL of 37% aqueous hydrochloric acid solution dropwise. After 20 min of reaction, the solvent was removed by rotary evaporator to obtain 1-methylimidazole hydrochloride, which can be used in the next reaction without further purification.
2. In a Q-tube reactor, 3.0 g of 1-methylimidazole hydrochloride and 2.28 g of dimethyl carbonate (DMC, 0.025 mol) were added. The reaction mixture was heated to 170 °C and kept for 2 h. Upon completion of the reaction, 1,3-dimethylimidazolium chloride was obtained in quantitative yield.
3. The structure of the product was confirmed by 1H-NMR (200 MHz, DMSO-d6): δ= 9.46 (s, 1H), 7.87 (s, 2H), 3.87 (m, 6H).
