Carbonium Ion

Name:
Carbonium Ion
Detailed information:
A positively charged organic ion, such as H₃C⁺, H₂RC⁺, R₃C⁺, etc., having one less electron than the corresponding free radical and acting in subsequent chemical reactions as though the positive charge were localized on the carbon atom. Such ions can exist only when corresponding negative ions are also present. An electron-deficient carbon atom is extremely reactive and has only a transitory existence in most cases, but many organic rearrangement and replacement reactions are effectively explained in terms of a carbonium-ion intermediate, including acid-catalyzed polymerization of propylene and other olefins. In this case, propylene and hydrogen ion form a carbonium ion as follows:H₃C—HC═CH₂ + H⁺ → H₃C—HC⁺—CH₃The latter then combines with another molecule of HC₃—HC═CH₂ to start chain growth.The difference between a carbonium ion, a free radical, and a carbanion may be illustrated as follows: