1,3,5-Trioxane

1,3,5-Trioxane, sometimes also called trioxane or trioxin, is a chemical compound with molecular formula C₃H₆O₃. It is a white solid with a chloroform-like odor. 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. Thus, cyclotrimerization of formaldehyde affords 1,3,5-trioxane:

The mechanism can be explained in an acidic catalyzed reaction:

In chemistry, 1,3,5-trioxane is used as a stable, easily handled source of anhydrous formaldehyde. In acidic solutions, it decomposes to generate three molecules of formaldehyde. It may also be used in polymerization to form acetal resins, such as polyoxymethylene plastic. It is a feedstock for certain types of plastic, is an ingredient in some solid fuel tablet formulas, and is used in chemical laboratories as a stable source of formaldehyde.