Combine 21 g salicylic acid, 27.2 g of urea and 1.6 g of boric acid in a 250 mL Erlenmeyer flask, cover the end with aluminum foil. Heat the mixture at 180°C for 2 h, then cool the mixture down and add 100 mL of water and 10 mL of 10% ammonia, boil the mixture for 5 minutes. Cool down and add 80 mL of 10M HCl, then filter off the salicylamide. Recrystallize in very hot ethanol-water solution.
Reaction taking place in 180°C
The crude product