Carbon suboxide

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Carbon suboxide
Image:Carbon-suboxide-2D-dimensions.png Image:Carbon-suboxide-3D-vdW.png
Molecular formula	C₃O₂
Molar mass	68.031 g mol⁻¹
Appearance	colourless gas
Properties
Density	3.0 kg/m³, gas at 298 K
Melting point	−107°C
Boiling point	6.8°C
Molecular shape	linear
Related compounds
Related oxides	carbon dioxide carbon monoxide dicarbon monoxide carbon trioxide
Related compounds	carbon subnitride
Infobox disclaimer and references

Carbon suboxide, C₃O₂, is a colorless pungent gas, with four cumulative double bonds, making it a cumulene. It is closely related to CO, CO₂ and C₂O, and other oxides of carbon.

Brodie discovered it in 1873 by submitting electric current to carbon monoxide.<ref>Brodie B. C. (1873). "Note on the Synthesis of Marsh-Gas and Formic Acid, and on the Electric Decomposition of Carbonic Oxide". Proceedings of the Royal Society (London) 21: 245-247.</ref><ref>Brodie B. C. (1873). "". Ann. 169: 270.</ref> Marcellin Berthelot created the name carbon suboxide, while Otto Diels later stated that the more organic names dicarbonyl methane and dioxallene were also correct.

It is synthesized by warming a dry mixture of phosphorus pentoxide (P₄O₁₀) and malonic acid or the esters of malonic acid. <ref>Diels O, Wolf B (1906). "". Ber. 39: 689.</ref>

Several other ways for synthesis and reactions of carbon suboxide can be found in a review from 1930 by Reyerson.<ref>Reyerson L. H., Kobe K. (1930). "Carbon Suboxide". Chemical Reviews 7: 479-492. DOI:10.1021/cr60028a002.</ref>

Carbon suboxide polymerizes spontaneously to a red to black solid. The structure is postulated to be poly(α-pyronic). <ref> M. Ballauff, L. Li, S. Rosenfeldt, N. Dingenouts, J. Beck, P. Krieger-Beck. "Analysis of Poly(carbon suboxide) by Small-Angle X-ray Scattering" 116 (43): 5967 - 5970. DOI:10.1002/anie.200460263.</ref> <ref>A. Ellern, T. Drews, K. Seppelt. "The Structure of Carbon Suboxide, C3O2, in the Solid State" 627, (1): 73 - 76. DOI:<73::AID-ZAAC73>3.0.CO;2-A 10.1002/1521-3749(200101)627:1<73::AID-ZAAC73>3.0.CO;2-A.</ref>