Hexamethylenetetramine or methenamine is a heterocyclic organic compound with the formula C6H12N4. This white crystalline compound is highly soluble in water and polar organic solvents. It has a cage-like structure similar to adamantane. It is useful in the synthesis of other chemical compounds, e.g., plastics, pharmaceuticals, rubber additives. It sublimes in vacuum at 280C.
Hexamethylenetetramine is prepared industrially by reacting formaldehyde and ammonia. The reaction can be conducted in gas phase and in solution.