Carbon subnitride
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| Carbon subnitride | |
|---|---|
| Image:Carbon subnitride.png | |
| Systematic name | 2-butynedinitrile |
| Molecular formula | NC4N |
| Molar mass | 76.06 g/mol |
| Density | 0.907 g/cm3 |
| Solubility (water) | x.xx g/l |
| Melting point | 20.5 °C |
| Boiling point | 76.5 °C |
| Standard enthalpy change of formation | –149.81 kcal/mol |
| CAS number | [1071-98-3] |
| Related compounds | |
| Related compounds | Carbon suboxide Cyanogen |
| 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.
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),<ref>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.</ref> which is the hottest flame of any chemical, according to Guinness World Records.
[edit] 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.<ref>Weis, C. D. (January 1963). "Reactions of Dicyanoacetylene". Journal of Organic Chemistry 28 (1): 74–78. DOI:10.1021/jo01036a015.</ref> Only the most reactive of dienophiles can attack aromatic dienes.
[edit] In outer space
Solid dicyanoacetylene has been detected in Titan's atmosphere by infrared spectroscopy.<ref>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.</ref> 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.<ref>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.</ref>
