{{Redirect-distinguish|Methylene glycol|Ethylene glycol}} {{Short description|Organic compound (CH2(OH)2); simplest geminal diol}} {{Chembox |Watchedfields = changed |verifiedrevid = 447495694 |ImageFile2 = Methanediol-3D-balls.png |ImageFile2_Ref = {{chemboximage|correct|??}} |ImageSize2 = 100 |ImageName2 = Ball and stick model of the methanediol |ImageClass2 = bg-transparent |ImageFileL1 = Methanediol-2D.png |ImageFileL1_Ref = {{chemboximage|correct|??}} |ImageNameL1 = Skeletal formula of methanediol with some explicit hydrogens added |ImageClassL1= skin-invert |ImageFileR1 = Methanediol-3D-vdW.png |ImageFileR1_Ref = {{chemboximage|correct|??}} |ImageNameR1 = Spacefill model of methanediol |ImageClassR1 = bg-transparent |PIN = Methanediol<ref>{{Cite web|title = Methanediol - Compound Summary|url = https://pubchem.ncbi.nlm.nih.gov/compound/79015|work = PubChem Compound|publisher = National Center for Biotechnology Information|access-date = 20 October 2011|location = USA|date = 26 March 2005|at = Identification and Related Records}}</ref> |OtherNames = {{unbulleted list|Formaldehyde hydrate|Formaldehyde monohydrate|Methylene glycol}} |Section1={{Chembox Identifiers |Abbreviations = MADOL |CASNo = 463-57-0 |CASNo_Ref = {{cascite|correct|??}} |UNII_Ref = {{fdacite|correct|FDA}} |UNII = 6Z20YM9257 |PubChem = 79015 |ChemSpiderID = 71348 |ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} |EINECS = 207-339-5 |ChEBI = 48397 |ChEBI_Ref = {{ebicite|correct|EBI}} |Beilstein = 1730798 |SMILES = OCO |StdInChI = 1S/CH4O2/c2-1-3/h2-3H,1H2 |StdInChI_Ref = {{stdinchicite|correct|chemspider}} |StdInChIKey = CKFGINPQOCXMAZ-UHFFFAOYSA-N |StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} }} |Section2={{Chembox Properties |C=1 | H=4 | O=2 |Appearance = Colourless liquid |Density = {{val|1.199|u=g/cm3}} {{Citation needed|date=October 2021}} |BoilingPtC = 194 |BoilingPt_notes = at 101 kPa {{Citation needed|date=October 2021}} |VaporPressure = 16.1 Pa {{Citation needed|date=October 2021}} |RefractIndex = 1.401 {{Citation needed|date=October 2021}} |pKa = 13.29<ref>{{cite journal|last=Bell|first=R. P.|author2=McTigue, P. T.|title=603. Kinetics of the aldol condensation of acetaldehyde|journal=Journal of the Chemical Society (Resumed)|year=1960|page=2983|doi=10.1039/JR9600002983}}</ref> }} |Section3={{Chembox Hazards |FlashPtC = 99.753 }} }}
'''Methanediol''', also known as '''formaldehyde monohydrate''' or '''methylene glycol''', is an organic compound with chemical formula {{chem2|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 ({{chem2|(CH2O)_{''n''} }}), formaldehyde ({{chem2|H2C\dO}}), and 1,3,5-trioxane ({{chem2|(CH2O)3}}).<ref name=Ullmann/>
Methanediol is a product of the hydration reaction of formaldehyde. The equilibrium constant for hydration is estimated to be 10<sup>3</sup>,<ref name="anslyn"> Eric V. Anslyn, Dennis A. Dougherty (2006), [https://books.google.com/books?id=gY-Sxijk_tMC&pg=PA544 ''Modern physical organic chemistry'']. University Science Books. {{ISBN|1-891389-31-9}}. 1095 pages</ref>{{chem2|CH2(OH)2}} predominates in dilute (<0.1%) solution. In more concentrated solutions, it oligomerizes to {{chem2|HO(CH2O)_{''n''}H}}.<ref name=Ullmann>{{Ullmann|doi=10.1002/14356007.a11_619|title=Formaldehyde|year=2000|last1=Reuss|first1=Günther|last2=Disteldorf|first2=Walter|last3=Gamer|first3=Armin Otto|last4=Hilt|first4=Albrecht|isbn=3527306730}}</ref>
==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.<ref name="zhu">{{cite journal |last1=Zhu |first1=Cheng |last2=Kleimeier |first2=N. Fabian |last3=Turner |first3=Andrew M. |last4=Singh |first4=Santosh K. |last5=Fortenberry |first5=Ryan C. |last6=Kaiser |first6=Ralf I. |title=Synthesis of methanediol [CH 2 (OH) 2 ]: The simplest geminal diol |journal=Proceedings of the National Academy of Sciences |date=4 January 2022 |volume=119 |issue=1 |article-number=e2111938119 |doi=10.1073/pnas.2111938119 |doi-access=free | pmid=34969838 |pmc=8740743 |bibcode=2022PNAS..11911938Z }}</ref>
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.<ref name="zhu"/>
==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.<ref>{{Cite web|url=https://www.osha.gov/SLTC/formaldehyde/hazard_alert.html|title=Hair Smoothing Products That Could Release Formaldehyde|publisher=Occupational Safety and Health Administration|website=www.osha.gov}}</ref><ref>{{cite web|title=Industry News|author=SpecialChem|url=http://www.specialchem4cosmetics.com/markets/hair-care/news.aspx?id=5947&lr=chal2d161210&li=100091733}}{{Dead link|date=January 2026 |bot=InternetArchiveBot}}</ref> 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.<ref name="Golden">{{cite journal|last1=Golden|first1=R.|last2=Valentini|first2=M.|title=Formaldehyde and methylene glycol equivalence: Critical assessment of chemical and toxicological aspects|journal=Regulatory Toxicology and Pharmacology|date=July 2014|volume=69|issue=2|pages=178–186|doi=10.1016/j.yrtph.2014.03.007|pmid=24709515|doi-access=free}}</ref>
==See also== * Orthoformic acid (methanetriol) * Orthocarbonic acid (methanetetrol)
==References==
{{Reflist}} {{Alcohols}}
Category:Hydrates Category:Carbohydrates Category:Geminal diols Category:Sugar alcohols