Carbonium ion

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In chemistry, carbonium ion is any cation that has a pentavalent carbon atom,[1][2] The name carbonium may also be used for the simplest member of the class, properly called methanium (CH+
5
), where the five valences are filled with hydrogen atoms.[3]

The next simplest carbonium ions after methanium have two carbon atoms. Ethynium, or protonated acetylene C
2
H+
3
, and ethenium C
2
H+
5
are usually classified in other families. The ethanium ion C
2
H+
7
has been studied as an extremely rarefied gas by infrared spectroscopy.[4] The isomers of octonium (protonated octane, C
8
H+
19
) have been studied.[5] The carbonium ion has a planar geometry.

In older literature the name "carbonium ion" was used for what is today called carbenium. The current definitions were proposed by the chemist George Andrew Olah in 1972[1] and are now widely accepted.

A stable carbonium ion is the complex pentakis(triphenylphosphinegold(I))methanium (Ph
3
PAu
)
5
C+
, produced by Schmidbauer and others.[6]

Preparation[edit]

Carbonium ions can be obtained by treating alkanes with very strong acids.[7] Industrially, they are formed in the refining of petroleum during primary thermal cracking.[8]

See also[edit]

References[edit]

  1. ^ a b George Andrew Olah (1972). "Stable carbocations. CXVIII. General concept and structure of carbocations based on differentiation of trivalent (classical) carbenium ions from three-center bound penta- or tetracoordinated (nonclassical) carbonium ions. Role of carbocations in electrophilic reactions". J. Am. Chem. Soc. 94 (3): 808–820. doi:10.1021/ja00758a020.
  2. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "Carbonium ion". doi:10.1351/goldbook.C00839
  3. ^ Boo, Doo Wan; Lee, Yuan T (1995). "Infrared spectroscopy of the molecular hydrogen solvated carbonium ions, CH+
    5
    (H
    2
    )
    n
    (n = 1–6)"
    . The Journal of Chemical Physics. 103 (2): 520. Bibcode:1995JChPh.103..520B. doi:10.1063/1.470138.
  4. ^ Yeh, L. I; Price, J. M; Lee, Yuan T (1989). "Infrared spectroscopy of the pentacoordinated carbonium ion C
    2
    H+
    7
    ". Journal of the American Chemical Society. 111 (15): 5597. doi:10.1021/ja00197a015.
  5. ^ Seitz, Christa; East, Allan L. L (2002). "Isomers of Protonated Octane, C
    8
    H+
    19
    ". The Journal of Physical Chemistry A. 106 (47): 11653. Bibcode:2002JPCA..10611653S. doi:10.1021/jp021724v.
  6. ^ George A. Olah (1998). Onium Ions. John Wiley & Sons. ISBN 9780471148777.
  7. ^ Sommer, J; Jost, R (2000). "Carbenium and carbonium ions in liquid- and solid-superacid-catalyzed activation of small alkanes". Pure and Applied Chemistry. 72 (12): 2309. doi:10.1351/pac200072122309.
  8. ^ Office of Energy Efficiency and Renewable Energy, U.S. DOE (2006). "Energy Bandwidth for Petroleum Refining Processes"