Dimethyl dioxane prepared from propylene glycol
| IUPAC name
| Other names
|Molar mass||116.16 g/mol|
|Density||0.932 g/cm3 (20 °C)|
|Melting point||−4.5 °C (23.9 °F; 268.6 K) |
|Boiling point||116.5–121 °C (241.7–249.8 °F; 389.6–394.1 K)|
|Solubility||Miscible with organic solvents|
|Safety data sheet||None|
|Flash point||23.9 °C (75 °F; 297 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Dimethyl dioxane (IUPAC: 2,5-Dimethyl-1,4-dioxane) is an organic compound, an ether with the chemical formula C6H12O2. It is commonly encountered as a mixture of cis and trans isomers.
Dimethyl dioxane is highly susceptible to acid catalyzed hydrolysis. A strong acid, like sulfuric acid will cause it to break down into propylene glycol and other side products. On the other hand, bases, like sodium hydroxide do not hydrolyze dimethyldioxane to any appreciable degree.
Dimethyl dioxane is a colorless liquid, with an ether-like odor. It is immiscible with water, but miscible with other organic solvents.
There doesn't appear to be any chemical suppliers that sells this chemical. Best to make it yourself.
Dimethyldioxane can be prepared by acid-catalyzed dehydration of propylene glycol. This can be done by adding a small amount of concentrated sulfuric acid to pure propylene glycol and distilling off the product. Remove the water from the distillate using a separatory funnel, then transfer the ether into a flask. To destroy all impurities, you cannot use acid, like in the case of dioxane, as dimethyldioxane is sensitive to acids. Instead, a base like sodium or potassium hydroxide should be used. Add the base flakes to the dimethyldioxane, then stir the product for a few hours to make sure all the impurities will polymerize. After all the impurities have polymerized, the final product should be reddish in color. To get a purer product, you can fractionally distill the ether, and collect the fraction boiling between 117-120 °C. 
For this process to work, you will need pure propylene glycol. Any impurities will poison the reaction, so it's best to distill the propylene glycol first.
- Liquid-liquid extractions
There is very little data about the toxicity of this chemical compound.
Like most ethers, dimethyl dioxane will slowly form explosive peroxides in storage, though addition of a small amount of butylated hydroxytoluene (BHT) or storage over sodium metal will prevent the formation of peroxides. Sodium hydroxide can also be used. Care must be taken not to distill the ether to dryness due to the trace amounts of peroxides formed over time.
Dimethyl dioxane can be safely burned, unless it has peroxides. If the ether tests positive for peroxides but there is no precipitate in the ether, it's possible to neutralize the dissolved peroxides. Reducing agents, like ferrous sulfate, sodium bisulfite or metabisulfite added in excess can be used to neutralize the peroxides. After neutralization, the ether should be tested again for peroxides and if none are present, it can be safely burned.
If it's an old bottle, which has visible peroxide in the solution, or if very old, is very likely to have peroxides on the cap, DO NOT OPEN THE BOTTLE! Instead take it to a remote of special area and safely detonate it. The latter may or may not require professional help, depending on the severity of the case.
- Summerbell et al.; Journal of Organic Chemistry; vol. 27; (1962); p. 4365,4367
- Zeiberlikh, F. N.; Lukoyanova, T. P.; Rogushina, T. K.; Korotkova, N. P.; Gladush, L. P.; Simenido, A. V.; J. Appl. Chem. USSR (Engl. Transl.); vol. 62; nb. 7.2; (1989); p. 1563 - 1567,1446 - 1450