Tetracyanoethylene

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Tetracyanoethylene
Tetracyanoethylene.png
tetracyanoethylene
Names
IUPAC name
ethenetetracarbonitrile
Other names
TCNE
Identifiers
670-54-2 YesY
ChemSpider 12114 YesY
Jmol interactive 3D Image
PubChem 12635
Properties
C6N4
Molar mass 128.09 g/mol
Density g/cm3
Melting point 199 °C (390 °F; 472 K)
Boiling point 130 to 140 °C (266 to 284 °F; 403 to 413 K) 0.1 mm Hg (sublimes)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Tetracyanoethylene (TCNE), more correctly ethenetetracarbonitrile, is a clear colored organic compound consisting of ethylene with the four hydrogen atom replaced with cyano groups. It is an important member of the cyanocarbons.

Synthesis and reactions[edit]

TCNE is prepared by brominating malononitrile in the presence of potassium bromide to give the KBr-complex, and dehalogenating with copper.[1]

Oxidation of TCNE with hydrogen peroxide gives the corresponding epoxide, which has unusual properties.[2]

Redox chemistry[edit]

TCNE is often used as an electron acceptor. Cyano groups have low energy π* orbitals, and the presence of four such groups, with their π systems linked (conjugated) to the central C=C double bond, gives rise to an excellent acceptor. Thus, treatment of TCNE with iodide salts gives the radical anion:

C2(CN)4 + I → [C2(CN)4] + 0.5 I2

Because of its planarity and its ability to accept electrons, TCNE has been used to prepare numerous organic superconductors, usually by serving as a single electron oxidant of an organic electron donor. Such charge-transfer salts are sometimes called Bechgaard salts.

Safety[edit]

TCNE hydrolyzes in moist air to give hydrogen cyanide and should be handled accordingly.[1]

References[edit]

  1. ^ a b c Carboni, R. A. (1963). "Tetracyanoethylene". Org. Synth. ; Coll. Vol. 4, p. 877 
  2. ^ Linn, W. J. (1973). "Tetracyanoethylene Oxide". Org. Synth. ; Coll. Vol. 5, p. 1007