1,3,5-Trioxane, sometimes also called trioxane or trioxin, is a chemical compound with molecular formula C3H6O3.
It is a stable cyclic trimer of formaldehyde, and one of the three trioxane isomers; its molecular backbone consists of a six-membered ring with three carbon atoms alternating with three oxygen atoms.
Trioxane can be obtained by the acid-catalyzed cyclic trimerization of formaldehyde in concentrated aqueous solution.
[2] Trioxane can be used interchangeably with formaldehyde and with paraformaldehyde,[3][4] however the cyclic structure is more stable and it can require high temperatures in order to react.
It is a precursor for the production of polyoxymethylene plastics, of which about one million tons per year are produced.