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| Names | |
|---|---|
| IUPAC name Ethene-1,2-dione | |
| Systematic IUPAC name Ethenedione | |
Other names
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| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| UNII | |
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| Properties | |
| C2O2 | |
| Molar mass | 56.020 g·mol−1 |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Ethylene dione orethylenedione, also calleddicarbon dioxide,carbon peroxide,ethenedione, orethene-1,2-dione, is achemical compound with theformulaC2O2 orO=C=C=O. It is anoxide ofcarbon (anoxocarbon), and can be described as the carbon-carbon covalentdimer ofcarbon monoxide.[1] It can also be thought of as thedehydrated form ofglyoxylic acid (H(C=O)COOH), or aketone ofethenoneH2C=C=O.
The existence of ethylenedione was first suggested in 1913.[2] However, for over a century the compound had eluded all attempts to synthesize and observe it, and it came to be considered a purelyhypothetical compound, or at best an "exceedingly coy molecule".[3]
In 2015, a research group reported the creation of ethylenedione — by usinglaser light to eject anelectron from the corresponding stable singly-chargedanionC2O−2 — and its spectroscopic characterization.[4] However, the reported spectrum was later found to match that of the oxyallyl diradical,(H2C•)2CO, formed by rearrangement or disproportionation under the high-energy experimental conditions rather than simple electron loss.[5]
Despite the existence of theclosed-shellKekulé structure, O=C=C=O, the lowest bound state of ethyledione is atriplet. It would then be adiradical, with anelectronic structure motif similar to theoxygen molecule. However, when the molecule is distorted away from its equilibrium geometry, the potential surfaces of the triplet andsinglet states intersect, allowing forintersystem crossing to the singlet state, which is unbound and dissociates to two ground-state CO molecules. The timescale of the intersystem crossing was predicted to be 0.5ns,[6] making triplet ethylenedione a transient, yet spectroscopically long-lived molecule.
On the other hand, the monoanion of ethylenedione, OCCO−, as well as the dianionC
2O2−
2, calledacetylenediolate, are both stable.[7][8]
Recent theoretical computations suggest that thein situ preparation and characterization of ethylenedione may be possible through low-energy free-electron induced single-molecule engineering.[1]
In the 1940s,Detroit physicianWilliam Frederick Koch claimed that he had synthesized this compound, which he calledglyoxylide, and that it was anantidote to thetoxins that caused a long list of ailments, includingdiabetes andcancer. The claims were false and the drug was classified as a fraud by theFDA.[9]
