Chemistry:Triphenylcarbenium

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Triphenylcarbenium
Space-filling model of the Ph
3
C+
ion

In chemistry, triphenylcarbenium,[1] triphenylmethyl cation, tritylium ,[2] or trityl cation is an ion with formula [C
19
H
15
]+
or (C
6
H
5
)
3
C+
, consisting of a carbon atom with a positive charge connected to three phenyl groups. It is a charged version of the triphenylmethyl radical (C
6
H
5
)
3
C•
. 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 [(C
6
H
5
)
3
C]+
[PF
6
]
. Related salts are known with diverse anions including tetrafluoroborate ([BF
4
]
),[1] hexachloroantimonate ([SbCl
6
]
), and perchlorate ([ClO
4
]
). 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 (C
6
Cl
5
)
3
C+
.[6]

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.[7]

See also

References

  1. 1.0 1.1 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. 
  4. 4.0 4.1 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. 
  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