1,3-Dioxane

1,3-Dioxane or m-dioxane is an organic compound with the molecular formula (CH2)4O2. It is a saturated six-membered heterocycle with two oxygen atoms in place of carbon atoms at the 1- and 3- positions. 1,4-Dioxane, which is of greater commercial value, is an isomer. Both dioxanes are colorless liquids.

Preparation and derivatives
The parent 1,3-dioxane is prepared by the reaction of formaldehyde and 1,3-propanediol in the presence of Brönsted or Lewis acid catalysts.

Substituted derivatives can be used as protecting groups for carbonyl compounds. are prepared from the reaction between a ketone or an aldehyde with 1,3-diols. They can also be produced by the Prins reaction.

Related compounds
1,3-Dioxolanes are five-membered rings with the formula (CH2)3O2.