Methanediol

"Methylene glycol" redirects here and is not to be confused with Ethylene glycol.

Methanediol, also known as formaldehyde monohydrate or methylene glycol, is an organic compound with chemical formula CH₂(OH)₂. It is the simplest geminal diol. In aqueous solutions it coexists with oligomers (short polymers). The compound is closely related and convertible to the industrially significant derivatives paraformaldehyde ((CH₂O)_n), formaldehyde (H₂C=O), and 1,3,5-trioxane ((CH₂O)₃).^[3]

Methanediol

Skeletal formula of methanediol with some explicit hydrogens added Spacefill model of methanediol
Ball and stick model of the methanediol
Names
Preferred IUPAC name Methanediol[1]
Other names Formaldehyde hydrate Formaldehyde monohydrate Methylene glycol
Identifiers
CAS Number	463-57-0 Y
3D model (JSmol)	Interactive image
Abbreviations	MADOL
Beilstein Reference	1730798
ChEBI	CHEBI:48397 Y
ChemSpider	71348 Y
ECHA InfoCard	100.006.673
EC Number	207-339-5
PubChem CID	79015
UNII	6Z20YM9257 Y
CompTox Dashboard (EPA)	DTXSID50196801
InChI InChI=1S/CH4O2/c2-1-3/h2-3H,1H2 Y Key: CKFGINPQOCXMAZ-UHFFFAOYSA-N Y
SMILES OCO
Properties
Chemical formula	CH4O2
Molar mass	48.041 g·mol−1
Appearance	Colourless liquid
Density	1.199 g/cm3 [citation needed]
Boiling point	194 °C (381 °F; 467 K) at 101 kPa [citation needed]
Vapor pressure	16.1 Pa [citation needed]
Acidity (pKa)	13.29[2]
Refractive index (nD)	1.401 [citation needed]
Hazards
Flash point	99.753 °C (211.555 °F; 372.903 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Methanediol is a product of the hydration of formaldehyde. The equilibrium constant for hydration is estimated to be 10³,^[4]CH₂(OH)₂ predominates in dilute (<0.1%) solution. In more concentrated solutions, it oligomerizes to HO(CH₂O)_nH.^[3]

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 and oxygen ices.^[5]

Methanediol is believed to occur as an intermediate in the decomposition of carbonyl compounds in the atmosphere, and as a product of ozonolysis on these compounds.^[5]

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 equilibrium with formaldehyde has caused concern since formaldehyde in hair straighteners is a health hazard.^[6][7] Research funded by the Professional Keratin Smoothing Council (PKSC), an industry association that represents selected manufacturers of professional-use only keratin smoothing products, has disputed the risk.^[8]

See also

• Orthoformic acid (methanetriol)
• Orthocarbonic acid (methanetetrol)