Add 3. 1g (0.025mol) o-methoxyphenol, 12ml ethanol and 4g(0. 1 mol) sodium hydroxide into a 100mL three-necked bottle equipped with an electric stirrer, reflux condenser and dropping funnel, and add 0.2 ml (mass of o-methoxyphenol) Start the agitator and slowly heat it to reflux. Add 2.5 ml (0.03 1 mol) chloroform at about 80℃, and drop it after 20 minutes. Then continue to stir under slight boiling for 65438+/-0h.

Carefully add 1mol/L hydrochloric acid aqueous solution to the reaction mixture to neutrality. NaCl solids were removed by suction filtration, and the filter residue was washed twice with about 10ml ethanol. The filtrate was collected, and triethylamine, chloroform and 2- hydroxy -3- methoxybenzaldehyde (isovanillin) were distilled by steam distillation until no oil droplets appeared. The rest of the reaction solution was extracted twice with 10mL ether each time, and the extracts were combined and dried with anhydrous sodium sulfate. After filtering out the desiccant, the ether was evaporated in the water bath, and the white solid product of vanillin was obtained with a yield of about 2.8g(76%%). The crude product was further recrystallized from ethanol, and the structure of the sample was characterized by infrared spectrum, indicating the attribution of the main absorption peaks. The melting point of pure vanillin is 8 1-83℃.