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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:

Trioxane molecule
IUPAC name
Other names
s-Trioxane; 1,3,5-Trioxacyclohexane; Trioxymethylene; Metaformaldehyde; Trioxin
3D model (JSmol)
ECHA InfoCard 100.003.466
RTECS number YK0350000
Molar mass 90.078 g·mol−1
Appearance White crystalline solid
Density 1.17 g/cm3 (65 °C)[1]
Melting point 62 °C (144 °F; 335 K)[1]
Boiling point 115 °C (239 °F; 388 K)[1]
221 g/L[1]
R-phrases (outdated) R22
S-phrases (outdated) S24/25
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point 45 °C (113 °F)[1]
Related compounds
Related compounds

1,2,4-Trioxane Polyoxymethylene

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Trioxane Synthesis V.1.svg


Trioxane is produced by trimerization of formaldehyde using acid catalysts. The reaction is conducted in concentrated aqueous solution and the product is separated by solvent extraction. An idealized mechanism is shown below:


Trioxane is mainly consumed in the production of polyoxymethylene plastics, of which about one million tons per year are produced.[2] Other applications exploit its tendency to release formaldehyde. As such it is used as a binder in textiles, wood products, etc. Trioxane is combined with hexamine and compressed into solid bars to make hexamine fuel tablets, used by the military and outdoorsmen as a cooking fuel.

In the laboratory, trioxane is used as an anhydrous source of formaldehyde.[3]

See alsoEdit


  1. ^ a b c d e Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  2. ^ Günther Reuss, Walter Disteldorf, Armin Otto Gamer, Albrecht Hilt "Formaldehyde" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a11_619
  3. ^ W. O. Teeters and M. A. Gradsten "Hexahydro-1,3,5-tripropionyl-s-triazine" Org. Synth. 1950, volume 30, 51. doi:10.15227/orgsyn.030.0051