Dissolve 16.38 g of vanillin in 54 mL of methanol, cool the solution to 0°C in an ice bath. Start adding dropwise 18.94 g (6.1 mL) of bromine, stir vigorously, make sure that the temperature stays below 10°C. After addition stir for 1h at room temperature. Then cool it down to freezer temperature and start adding slowly 30 mL of water over 30 minutes. Filter and wash four times with 30 mL of water and then with 30 mL of 70% aq.MeOH.
Addition of the bromine
Stir for 1h in room temp
Cooled the solution down and added water slowly
Filtering and washing