Dimethoxymethane, also called methylal, is a colorless flammable liquid with a low boiling point, low

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...

and excellent dissolving power. It has a

chloroform Chloroform, or trichloromethane, is an organic compound with formula C H Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to PTFE. It is also a precursor to various re ...

-like odor and a pungent taste. It is the dimethyl

acetal In organic chemistry, an acetal is a functional group with the connectivity . Here, the R groups can be organic fragments (a carbon atom, with arbitrary other atoms attached to that) or hydrogen, while the R' groups must be organic fragment ...

formaldehyde Formaldehyde ( , ) ( systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section ...

. Dimethoxymethane is soluble in three parts water and miscible with most common organic solvents.

Synthesis and structure

It can be manufactured by oxidation of methanol or by the reaction of formaldehyde with methanol. In aqueous acid, it is

hydrolyzed Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

back to formaldehyde and methanol. Due to the anomeric effect, dimethoxymethane has a preference toward the ''gauche'' conformation with respect to each of the C–O bonds, instead of the ''anti'' conformation. Since there are two C–O bonds, the most stable conformation is ''gauche''-''gauche'', which is around 7 kcal/mol more stable than the ''anti''-''anti'' conformation, while the ''gauche''-''anti'' and ''anti-gauche'' are intermediate in energy. Since it is one of the smallest molecules exhibiting this effect, which has great interest in carbohydrate chemistry, dimethoxymethane is often used for theoretical studies of the anomeric effect.

Applications

Industrially, it is primarily used as a solvent and in the manufacture of perfumes, resins, adhesives, paint strippers and protective coatings. Another application is as a gasoline-additive for increasing

octane number An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating. The higher the octane number, the more compression the fuel can withstand before detonating. ...

. Dimethoxymethane can also be used for blending with diesel.

Reagent in organic synthesis

Another useful application of dimethoxymethane is to protect alcohols with a methoxymethyl (MOM) ether in organic synthesis. This can be done using

phosphorus pentoxide Phosphorus pentoxide is a chemical compound with molecular formula P4 O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydra ...

in dry

dichloromethane Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible wit ...

. This is a preferred method to using

chloromethyl methyl ether Chloromethyl methyl ether (CMME) is a compound with formula CH3OCH2Cl. A colorless liquid, it is a chloroalkyl ether. It is used as an alkylating agent. In organic synthesis, it is used for introducing the methoxymethyl ether (MOM) protecting ...

(MOMCl). Alternatively, MOMCl can be prepared as a solution in a methyl ester solvent by reacting dimethoxymethane and an acyl chloride in the presence of a Lewis acid catalyst like zinc bromide: MeOCH₂OMe + RC(=O)Cl → MeOCH₂Cl + RC(=O)(OMe)). The solution of the reagent can be used directly without purification, minimizing contact with the carcinogenic chloromethyl methyl ether. Unlike the classical procedure, which uses formaldehyde and hydrogen chloride as starting materials, the highly carcinogenic side product bis(chloromethyl) ether is not generated.

References

External links

* {{Authority control Ether solvents Formals Methoxy compounds