Dihydroxymethylidene

Dihydroxymethylidene
	; Ball and stick model of dihydroxymethylidene Carbon, C Hydrogen, H Oxygen, O
Names
	IUPAC name Carbon(II) hydroxide; Carbon dihydroxide; Carbonous hydroxide;
	Preferred IUPAC name Dihydroxymethylidene
	Other names Carbonic(II) acid; Carbonous acid; Dihydroxycarbene; Dihydroxymethylene; Dihydroxycarbon(2•);
Identifiers
CAS Number	71946-83-3 ;
3D model (JSmol)	Interactive image;
ChemSpider	11646598 ;
MeSH	Dihydroxycarbene
PubChem CID	191992;
CompTox Dashboard (EPA)	DTXSID70222232 ;
	InChI InChI=1S/CH2O2/c2-1-3/h2-3H Key: VZOMUUKAVRPMBY-UHFFFAOYSA-N ;
	SMILES O[C]O;
Properties
Chemical formula	C(OH)2
Molar mass	46.025 g·mol−1
Related compounds
Related compounds	Tin(II) hydroxide; Lead(II) hydroxide; Formic acid; Orthocarbonic acid;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Dihydroxymethylidene or carbonous acid is a chemical compound with formula C(OH)₂. It is an unstable tautomer of formic acid. There is no evidence that this compound exists in solution, but the molecule has been detected in the gas phase.^[1] Many related carbenes are known, although they are often transient.^[2]

Production and properties

Dihydroxymethylidene is produced in the gas phase by high vacuum flash vacuum pyrolysis of oxalic acid:

H₂C₂O₄ → C(OH)₂ + CO₂

The species is a bent molecule with an O−C−O angle of 105.6° for the C_2v all-trans rotamer. Although stable at 10 K, at higher temperatures it isomerizes to formic acid.

The double ionized ion, CO2−2, is known as the carbonite ion.

References

^ Schreiner, Peter R.; Reisenauer, Hans Peter (2008). "Spectroscopic Identification of Dihydroxycarbene". Angewandte Chemie International Edition. 47 (37): 7071–7074. doi:10.1002/anie.200802105. PMID 18666191.
^ M. Jones, Jr., R. A. Moss, in "Reactive Intermediate Chemistry", Edited by R. A. Moss, M. S. Platz, M. Jones, Jr., Wiley-Interscience, Hoboken, 2004.

[1] Schreiner, Peter R.; Reisenauer, Hans Peter (2008). "Spectroscopic Identification of Dihydroxycarbene". Angewandte Chemie International Edition. 47 (37): 7071–7074. doi:10.1002/anie.200802105. PMID 18666191.

[2] M. Jones, Jr., R. A. Moss, in "Reactive Intermediate Chemistry", Edited by R. A. Moss, M. S. Platz, M. Jones, Jr., Wiley-Interscience, Hoboken, 2004.

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