Tetracyanoethylene

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Tetracyanoethylene
Tetracyanoethylene.png tetracyanoethylene
Identifiers
CAS number 670-54-2 YesY
PubChem 12635
ChemSpider 12114 YesY
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]
Except where noted otherwise, 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: 877 
  2. ^ Linn, W. J. (1973), "Tetracyanoethylene Oxide", Org. Synth. ; Coll. Vol. 5: 1007