Dicyanoacetylene

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Dicyanoacetylene
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 ΔfHo298		 +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

Dicyanoacetylene (also carbon subnitride, IUPAC but-2-ynedinitrile), 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, dicyanoacetylene 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.

[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.[2] 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.[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]

[edit] References

  1. ^ 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. 
  2. ^ Weis, C. D. (January 1963). "Reactions of Dicyanoacetylene". Journal of Organic Chemistry 28 (1): 74–78. doi:10.1021/jo01036a015. 
  3. ^ 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. 
  4. ^ 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.