To 50 mL of warm ethanol dissolve 1 g of urea and 2 g of benzil, then add 2 g of potassium hydroxide and reflux for 6 h. Pour the refluxed solution into 70 mL of water and filter, discard the precipitate. Then with stirring add as much of HCI until the pH becomes 4, filter and wash with 50 mL of cold water. Recrystallize in hot ethanol.
Refluxing the mixture
Addition of water
Precipitating the product with HCI
The crude product
The recrystallized product