Methanediol, also known as formaldehyde monohydrate or methylene glycol, is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

with

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

. It is the simplest geminal diol, and the simplest

sugar alcohol Sugar alcohols (also called polyhydric alcohols, polyalcohols, alditols or glycitols) are organic compounds, typically derived from sugars, containing one hydroxyl group (–OH) attached to each carbon atom. They are white, water-soluble solids ...

. In aqueous solutions it coexists with

oligomer In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relati ...

s (short polymers). The compound is closely related and convertible to the industrially significant derivatives

paraformaldehyde Paraformaldehyde (PFA) is the smallest polyoxymethylene, the polymerization product of formaldehyde with a typical degree of polymerization of 8–100 units. Paraformaldehyde commonly has a slight odor of formaldehyde due to decomposition. Par ...

(),

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 ...

(), and

1,3,5-trioxane 1,3,5-Trioxane, sometimes also called trioxane or trioxin, is a chemical compound with molecular formula CHO. It is a white, highly water-soluble solid with a chloroform-like odor. It is a stable cyclic trimer of formaldehyde, and one of the t ...

(). Methanediol is a product of the

hydration Hydration may refer to: * Hydrate, a substance that contains water * Hydration enthalpy, energy released through hydrating a substance * Hydration reaction, a chemical addition reaction where a hydroxyl group and proton are added to a compound * ...

of formaldehyde. The

equilibrium constant The equilibrium constant of a chemical reaction is the value of its reaction quotient at chemical equilibrium, a state approached by a dynamic chemical system after sufficient time has elapsed at which its composition has no measurable tendency ...

for hydration is estimated to be 10³, Eric V. Anslyn, Dennis A. Dougherty (2006)
''Modern physical organic chemistry''
University Science Books. . 1095 pages predominates in dilute (<0.1%) solution. In more concentrated solutions, it oligomerizes to .

Occurrence

The dianion, methanediolate, is believed to be an intermediate in the crossed Cannizzaro reaction. Gaseous methanediols can be generated by electron irradiation and sublimation of a mixture of

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is ...

and

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

ices. Methanediol is believed to occur as an intermediate in the decomposition of

carbonyl In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containi ...

compounds in the atmosphere, and as a product of

ozonolysis In organic chemistry, ozonolysis is an organic reaction where the unsaturated bonds of alkenes (), alkynes (), or azo compounds () are cleaved with ozone (). Alkenes and alkynes form organic compounds in which the multiple carbon–carbon b ...

on these compounds.

Safety

Methanediol, rather than formaldehyde, is listed as one of the main ingredients of " Brazilian blowout", a hair-straightening formula marketed in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

. The equilibrium with formaldehyde has caused concern since formaldehyde in hair straighteners is a health hazard, but the risk has been disputed.

References

{{Alcohols Hydrates Carbohydrates Geminal diols Sugar alcohols

Occurrence

Safety

See also

References