Dicyanoacetylene

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Dicyanoacetylene
Dicyanoacetylene Structural Formula V2.svg
Carbon-subnitride-3D-balls.png
Carbon-subnitride-3D-vdW.png
Names
Preferred IUPAC name
But-2-ynedinitrile
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1S/C4N2/c5-3-1-2-4-6 X mark.svgN
    Key: ZEHZNAXXOOYTJM-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C4N2/c5-3-1-2-4-6
    Key: ZEHZNAXXOOYTJM-UHFFFAOYAR
  • N#CC#CC#N
Properties
C4N2
Molar mass 76.058 g·mol−1
Density 0.907 g/cm3
Melting point 20.5 °C (68.9 °F; 293.6 K)
Boiling point 76.5 °C (169.7 °F; 349.6 K)
Thermochemistry
+500.4 kJ/mol
Related compounds
Related compounds
Carbon suboxide
Cyanogen
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Dicyanoacetylene, also called carbon subnitride or but-2-ynedinitrile (IUPAC), is a compound of carbon and nitrogen with chemical formula C4N2. It has a linear molecular structure, N≡C−C≡C−C≡N (often abbreviated as NC4N), with alternating triple and single covalent bonds. It can be viewed as acetylene with the two hydrogen atoms replaced by cyanide groups.

Contents

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 5,260 K (4,990 °C; 9,010 °F), the hottest flame in oxygen; burned in ozone at high pressure the flame temperature exceeds 6,000 K (5,730 °C; 10,340 °F). [1]

Synthesis

Dicyanoacetylene can be prepared by passing nitrogen gas over a sample of graphite heated to temperatures between 2,673 and 3,000 K (2,400 and 2,727 °C; 4,352 and 4,940 °F). [2] It may also be synthesized via a reaction between a dihaloacetylene and a cyanide salt:[ citation needed ]

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. [3] Only the most reactive of dienophiles can attack such aromatic compounds.

In outer space

Solid dicyanoacetylene has been detected in the atmosphere of Titan by infrared spectroscopy. [4] As the seasons change on Titan, the compound condenses and evaporates in a cycle, which allows scientists on Earth to study 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 its presence in those environments is therefore suspected. [5]

See also

Related Research Articles

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Aromatic compounds or arenes usually refers to organic compounds "with a chemistry typified by benzene" and "cyclically conjugated." The word "aromatic" originates from the past grouping of molecules based on odor, before their general chemical properties were understood. The current definition of aromatic compounds does not have any relation to their odor. Aromatic compounds are now defined as cyclic compounds satisfying Hückel's Rule. Aromatic compounds have the following general properties:

<span class="mw-page-title-main">Amine</span> Chemical compounds and groups containing nitrogen with a lone pair (:N)

In chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Formally, amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines, trimethylamine, and aniline. Inorganic derivatives of ammonia are also called amines, such as monochloramine.

<span class="mw-page-title-main">Nitrogen</span> Chemical element with atomic number 7 (N)

Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure, two atoms of the element bond to form N2, a colorless and odorless diatomic gas. N2 forms about 78% of Earth's atmosphere, making it the most abundant chemical species in air. Because of the volatility of nitrogen compounds, nitrogen is relatively rare in the solid parts of the Earth.

<span class="mw-page-title-main">Pyridine</span> Heterocyclic aromatic organic compound

Pyridine is a basic heterocyclic organic compound with the chemical formula C5H5N. It is structurally related to benzene, with one methine group (=CH−) replaced by a nitrogen atom (=N−). It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide.

<span class="mw-page-title-main">Hydrogen cyanide</span> Highly toxic chemical with the formula HCN

Hydrogen cyanide is a chemical compound with the formula HCN and structural formula H−C≡N. It is a highly toxic and flammable liquid that boils slightly above room temperature, at 25.6 °C (78.1 °F). HCN is produced on an industrial scale and is a highly valued precursor to many chemical compounds ranging from polymers to pharmaceuticals. Large-scale applications are for the production of potassium cyanide and adiponitrile, used in mining and plastics, respectively. It is more toxic than solid cyanide compounds due to its volatile nature. A solution of hydrogen cyanide in water, represented as HCN, is called hydrocyanic acid. The salts of the cyanide anion are known as cyanides.

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References

  1. Kirshenbaum, A. D.; Grosse, A. V. (1956). "The Combustion of Carbon Subnitride, C4N2, and a Chemical Method for the Production of Continuous Temperatures in the Range of 5000–6000K". Journal of the American Chemical Society. 78 (9): 2020. doi:10.1021/ja01590a075.
  2. Ciganek, E.; Krespan, C. G. (1968). "Syntheses of Dicyanoacetylene". The Journal of Organic Chemistry. 33 (2): 541–544. doi:10.1021/jo01266a014.
  3. Weis, C. D. (1963). "Reactions of Dicyanoacetylene". Journal of Organic Chemistry. 28 (1): 74–78. doi:10.1021/jo01036a015.
  4. Samuelson, R. E.; Mayo, L. A.; Knuckles, M. A.; Khanna, R. J. (1997). "C4N2 Ice in Titan's North Polar Stratosphere". Planetary and Space Science. 45 (8): 941–948. Bibcode:1997P&SS...45..941S. doi:10.1016/S0032-0633(97)00088-3.
  5. Kołos, R. (2002). "Exotic Isomers of Dicyanoacetylene: A Density Functional Theory and ab initio Study". Journal of Chemical Physics. 117 (5): 2063–2067. Bibcode:2002JChPh.117.2063K. doi:10.1063/1.1489992.