Triphenylcarbenium

In chemistry, triphenylcarbenium,[1] triphenylmethyl cation, tritylium ,[2] or trityl cation is an ion with formula [C
19H
15]+
 or (C
6H
5)
3C+
, consisting of a carbon atom with a positive charge connected to three phenyl groups. It is a charged version of the triphenylmethyl radical (C
6H
5)
3C•. The name is often abbreviated to triphenylmethyl or trityl in salts, although these names also denote the chemical group in compounds like triphenylmethyl chloride that do not contain the cation.

Triphenylcarbenium
Space-filling model of the Ph3C+ ion

Triphenylcarbenium is a relatively stable carbenium ion, because the positive charge can be distributed among 10 of the carbon atoms (the 3 carbon atoms in the ortho and para positions of each of the three phenyl groups, plus the central carbon atom).[3][4] The cation exists in important chemical reagents and catalysts such as

  • Triphenylmethyl hexafluorophosphate [(C
    6    H
    5    )
    3    C]+
    [PF
    6    ]−
  • Triphenylmethyl tetrafluoroborate [(C
    6    H
    5    )
    3    C]+
    [BF
    4    ]−
     [1]
  • Triphenylcarbenium hexachloroantimonate [(C
    6    H
    5    )
    3    C]+
    [SbCl
    6    ]−
  • Triphenylmethyl perchlorate [(C
    6    H
    5    )
    3    C]+
    [ClO
    4    ]−

This and other similar cations can be obtained as intensely colored solutions by dissolving aryl-substituted methanols in concentrated sulfuric acid.[3]

Derivatives

Derivatives of this cation include, for example, perchlorotriphenylcarbenium (C
6Cl
5)
3C+
.[5]

Triarylmethane dyes

Triarylmethane dyes are derivatives are stabilized version of the trityl cation. They are water-soluble and are often obtained as the chloride salts. These dyes have strong electron donor groups, often amines, at the p-positions of two or three of the aryl groups.[6]

See also

References
  1. Michael E. Jung, Roman Lagoutte, and Ullrich Jahn (2011): "Triphenylcarbenium Tetrafluoroborate". In Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt362.pub2
  2. U. S. National Institutes of Health (2019) "PubChem ID 2723954 - Triphenylcarbenium hexafluorophosphate". Entry in NCBI's PubChem database, accessed on 2019-07-25.
  3. N. C. Deno, J. J. Jaruzelski, and Alan Schriesheim (1955) "Carbonium ions. I. An acidity function (C0) derived from arylcarbonium ion equilibria." Journal of the American Chemical Society, voume 77, issue 11, pages 3044–3051. doi:10.1021/ja01616a036
  4. Urch, C. (2001). Triphenylmethyl Hexafluorophosphate. Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt363f. ISBN 978-0471936237.
  5. E. Molins, M. Mas, W. Maniukiewicz, M. Ballester and J. Castañer (1996): "Perchlorotriphenylcarbenium Hexachloroantimonate(V)". Acta Crystallographica Section C (Structural Chemistry), volume C52, pages 2412-2414. doi:10.1107/S0108270196007287
  6. Thomas Gessner and Udo Mayer "Triarylmethane and Diarylmethane Dyes" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim.doi:10.1002/14356007.a27_179
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