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

Space-filling model of the Ph₃C⁺ ion

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