To a beaker immersed in an ice bath add 200 mL of conc. formaldehyde and start adding slowly 320 mL of 30 % ammonium hydroxide solution, the temperature must be kept below 20°C. Then evaporate the water off by heating the flask in a hot water bath, recrystallize the hexamine in hot ethanol.
Addition of the ammonia solution
Evaporation of the water
The dry product