Chemistry:Carbonium ion
In chemistry, a carbonium ion is any cation that has a pentacoordinated 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 carbon atom is covalently bonded to five hydrogen atoms.[3][4][5][6]
The next simplest carbonium ions after methanium have two carbon atoms. Ethynium, or protonated acetylene C
2H+
3, and ethenium C
2H+
5 are usually classified in other families. The ethanium ion C
2H+
7 has been studied as an extremely rarefied gas by infrared spectroscopy.[7] The isomers of octonium (protonated octane, C
8H+
19) have been studied.[8] 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
3PAu)
5C+
, produced by Schmidbauer and others.[9]
Preparation
Carbonium ions can be obtained by treating alkanes with very strong acids.[10] Industrially, they are formed in the refining of petroleum during primary thermal cracking (Haag-Dessau mechanism).[11][12]
See also
- Fluxional molecules
- More carbonium ions called non-classical ions are found in certain norbornyl systems
- Onium compounds
- Carbenium ion
References
- ↑ 1.0 1.1 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.
- ↑ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "Carbonium ion". doi:10.1351/goldbook.C00839
- ↑ Boo, Doo Wan; Lee, Yuan T (1995). "Infrared spectroscopy of the molecular hydrogen solvated carbonium ions, CH+5(H2)n (n = 1–6)". The Journal of Chemical Physics 103 (2): 520. doi:10.1063/1.470138. Bibcode: 1995JChPh.103..520B. https://zenodo.org/record/1232938.
- ↑ Asvany, O.; Kumar P, P.; Redlich, B.; Hegemann, I.; Schlemmer, S.; Marx, D. (2005). "Understanding the Infrared Spectrum of Bare CH5+". Science 309 (5738): 1219–1222. doi:10.1126/science.1113729. PMID 15994376. Bibcode: 2005Sci...309.1219A.
- ↑ Xiao-Gang Wang; Tucker Carrington Jr (2016). "Calculated rotation-bending energy levels of CH5+ and a comparison with experiment". Journal of Chemical Physics 144 (20): 204304. doi:10.1063/1.4948549. PMID 27250303. Bibcode: 2016JChPh.144t4304W.
- ↑ H. Schmiedt; Per Jensen; S. Schlemmer (2017). "Rotation-vibration motion of extremely flexible molecules - The molecular superrotor". Chemical Physics Letters 672: 34–46. doi:10.1016/j.cplett.2017.01.045. Bibcode: 2017CPL...672...34S.
- ↑ Yeh, L. I; Price, J. M; Lee, Yuan T (1989). "Infrared spectroscopy of the pentacoordinated carbonium ion C2H+7". Journal of the American Chemical Society 111 (15): 5597. doi:10.1021/ja00197a015.
- ↑ Seitz, Christa; East, Allan L. L (2002). "Isomers of Protonated Octane, C8H+19". The Journal of Physical Chemistry A 106 (47): 11653. doi:10.1021/jp021724v. Bibcode: 2002JPCA..10611653S.
- ↑ George A. Olah (1998). Onium Ions. John Wiley & Sons. ISBN 9780471148777.
- ↑ 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.
- ↑ Office of Energy Efficiency and Renewable Energy, U.S. DOE (2006). "Energy Bandwidth for Petroleum Refining Processes"
- ↑ Kotrel, S.; Knözinger, H.; Gates, B.C. (April 2000). "The Haag–Dessau mechanism of protolytic cracking of alkanes" (in en). Microporous and Mesoporous Materials 35-36: 11–20. doi:10.1016/S1387-1811(99)00204-8. https://linkinghub.elsevier.com/retrieve/pii/S1387181199002048.
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