Carbonium Ions

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Related to Carbonium Ions: Carbenium ion

Carbonium Ions


molecular particles containing a triva-lent positively charged carbon atom. Carbonium ions are highly reactive and therefore unstable. They form on heterolytic cleavage of the C—X bond (the electron pair which effects this bond is removed with the X group):

For example, the action of strong acids on triphenyl carbinol yields a triphenylmethyl cation salt:

This carbonium ion is stable due to the distribution of the positive charge among several carbon atoms. Carbonium ions also form during the action of aprotic acids on halogen derivatives, for example

They also form during the addition of a proton or other cation to the multiple bond:

Carbonium ions readily interact with anions, with molecules containing an unshared electron pair or a multiple bond, and with other compounds, attacking areas with increased electron density. Carbonium ions are intermediate particles in many organic reactions of both theoretical and practical value (for example, alkylation and acylation according to the Friedel-Crafts reaction, reactions of electrophilic combination with olefins, iso-merization and cation polymerization of olefins, and pinacolic and retropinacolic, Dem’ianov, and Wagner-Meerwein rearrangements).


Breslow, R. Mekhanizmy organicheskikh reaktsii. Moscow, 1968. (Translated from English.)
Roberts, J., and M. Caserio. Osnovy organicheskoi khimii, parts 1–2. Moscow, 1968. (Translated from English.)


References in periodicals archive ?
Increasing temperature could improve both of the diffusion velocity of carbonium ions (+C[H.
As for catalytic pyrolysis of C4 hydrocarbons, butene can form isobutyl and tert-butyl carbonium ions that are hard to crack because there are no [beta]C-C bonds in the molecular structure.
This rule allows carbonium ions of different structure to be distinguished between those that could create tumors in organisms and those that cannot (ref.