Paraldehyde is the cyclic trimer of acetaldehyde molecules. Formally, it is a derivative of 1,3,5-trioxane, with a methyl groups substituted for a hydrogen atoms in each carbon.
P 1338 (OTTO) Paraldehyde, 97% Cas 123-63-7 - used in resin manufacture, as a preservative, MEP and in other processes as a solvent.