1.7g of glycoluril is combined with 930mg of paraformaldehyde and 5ml of conc. HCl, then the solution is heated at 95°C with stirring for 24h. The solution is filtered and the powder is discarded. Then the solution is allowed to stand at 5°C for several days. until large crystals form.
Heating the solution
The white powder below the crystals is discarded
The pure product