Tetracyanoethylene

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Tetracyanoethylene
Tetracyanoethylene.png
tetracyanoethylene
Names
IUPAC name
Ethenetetracarbonitrile
Other names
TCNE
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.010.527
Properties
C6N4
Molar mass 128.09 g·mol−1
Density 1.35 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 mmHg (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) is a clear colored organic compound consisting of ethylene with the four hydrogen atoms 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] + ​12 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". Organic Syntheses.; Collective Volume, 4, p. 877
  2. ^ Linn, W. J. (1973). "Tetracyanoethylene Oxide". Organic Syntheses.; Collective Volume, 5, p. 1007