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Carbon subnitride

Carbon subnitride

Identifiers
CAS number	1071-98-3
Properties
Molecular formula	NC₄N
Molar mass	76.06 g/mol
Density	0.907 g/cm³
Melting point	20.5 °C
Boiling point	76.5 °C
Thermochemistry
Std enthalpy of formation Δ_fH^o₂₉₈	+500.4 kJ/mol
Related Compounds
Related compounds	Carbon suboxide Cyanogen
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Carbon subnitride or dicyanoacetylene (C₄N₂) is a compound of carbon and nitrogen. It has a linear structure, NCCCCN, with alternating triple and single covalent bonds. In other words, it is acetylene with the two hydrogen atoms replaced by cyanide groups.

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At room temperature, carbon subnitride is a clear liquid. Because of its high endothermic heat of formation, it can explode to carbon powder and nitrogen gas, and it burns in oxygen with a bright blue-white flame at a temperature of 5260 K (4987 °C, 9008 °F),^[1] which is the hottest flame of any chemical, according to Guinness World Records.

As a reagent in organic chemistry

Dicyanoacetylene is a powerful dienophile because the cyanide groups are electron-withdrawing, so it is a useful reagent for Diels-Alder reactions with unreactive dienes. It even adds to the aromatic compound durene (1,2,4,5-tetramethylbenzene) to form a substituted bicyclooctatriene.^[2] Only the most reactive of dienophiles can attack aromatic dienes.

In outer space

Solid dicyanoacetylene has been detected in Titan's atmosphere by infrared spectroscopy.^[3] As the seasons change on Titan, the C₄N₂ condenses and evaporates in a cycle, which allows scientists on Earth to discover things about Titanian meteorology.

As of 2006, the detection of dicyanoacetylene in the interstellar medium has been impossible, because its symmetry means it has no rotational microwave spectrum. However, similar asymmetric molecules like cyanoacetylene have been observed, and it is suspected that advances in astronomical infrared spectroscopy will lead to the detection of interstellar C₄N₂.^[4]

References

^ Kirshenbaum, A. D.; and A. V. Grosse (May 1956). "The Combustion of Carbon Subnitride, C₄N₂, and a Chemical Method for the Production of Continuous Temperatures in the Range of 5000–6000°K". Journal of the American Chemical Society 78 (9): 2020. doi:10.1021/ja01590a075.
^ Weis, C. D. (January 1963). "Reactions of Dicyanoacetylene". Journal of Organic Chemistry 28 (1): 74–78. doi:10.1021/jo01036a015.
^ Samuelson, R. E.; L. A. Mayo, M. A. Knuckles, and R. J. Khanna (August 1977). "C₄N₂ ice in Titan's north polar stratosphere". Planetary and Space Science 45 (8): 941–948. doi:10.1016/S0032-0633(97)00088-3.
^ Kołos, Robert (August 2002). "Exotic isomers of dicyanoacetylene: A density functional theory and ab initio study". Journal of Chemical Physics 117 (5): 2063–2067. doi:10.1063/1.1489992.

Categories: Inorganic carbon compounds | Nitrides

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Carbon_subnitride". A list of authors is available in Wikipedia.