Tetracyanoethylene

Tetracyanoethylene
IUPAC name

tetracyanoethene
Other names

TCNE
Identifiers
CAS number 670-54-2 Y
PubChem 12635
ChemSpider 12114 Y
Jmol-3D images Image 1
Properties
Molecular formula C6N4
Molar mass 128.09 g/mol
Density g/cm3
Melting point

199 °C
Boiling point

130-140 °C, 0.1 mm Hg (sublimes)[1]
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tetracyanoethylene (TCNE) 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.

Contents

Synthesis and reactions

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

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 salt.

Safety

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

References

  1. ^ a b c Carboni, R. A. (1963), "Tetracyanoethylene", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv4p0877 ; Coll. Vol. 4: 877 
  2. ^ Linn, W. J. (1973), "Tetracyanoethylene Oxide", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv5p1007 ; Coll. Vol. 5: 1007