Triphenylcarbenium

In chemistry, triphenylcarbenium,[1] triphenylmethyl cation, tritylium ,[2] or trityl cation is an ion with formula [C19H15]+ or (C6H5)3C+, consisting of a carbon atom with a positive charge connected to three phenyl groups. It is a charged version of the triphenylmethyl radical (C6H5)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.[3]

Triphenylcarbenium is a relatively stable carbenium ion, because the positive charge is partially 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).[4][5]

Derivatives

The cation exists in important chemical reagents and catalysts such as triphenylmethyl hexafluorophosphate [(C6H5)3C]+[PF6]−. Related salts are known with diverse anions including tetrafluoroborate ([BF4]−),[1] hexachloroantimonate ([SbCl6]−), and perchlorate ([ClO4]−). This and other similar cations can be obtained as intensely colored solutions by dissolving aryl-substituted methanols in concentrated sulfuric acid.[4] Derivatives of this cation include, for example, perchlorotriphenylcarbenium (C6Cl5)3C+.[6]

Triarylmethane dyes

Triarylmethane dyes are derivatives that are stabilized versions 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.[7]

  • Triarylmethane dyes
  • Crystal violet.
  • New fuchsine dye.
  • Pararosaniline

See also
  • Triphenylmethane (C6H5)3CH
  • Triphenylmethanol (C6H5)3COH

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. Naidu, Veluru Ramesh; Ni, Shengjun; Franzén, Johan (2015). "The Carbocation: A Forgotten Lewis Acid Catalyst". ChemCatChem. 7 (13): 1896–1905. doi:10.1002/cctc.201500225. S2CID 98267361.
  4. 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
  5. Urch, C. (2001). "Triphenylmethyl Hexafluorophosphate". doi:10.1002/047084289X.rt363f. ISBN 978-0471936237. {{cite book}}: |journal= ignored (help); Missing or empty |title= (help)
  6. 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
  7. 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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