Carbocation

Carbocation is a general term for <a href="/facts/Ion/3bePpDna">ions</a> with a positively charged <a href="/facts/Carbon/ukrgQexo">carbon</a> <a href="/facts/Atom/FoQ4kGN5">atom</a>. In the present-day definition given by the IUPAC, a carbocation is any even-electron cation with significant partial positive charge on a carbon atom. They are further classified in two main categories according to the <a href="/facts/Coordination_number/mf48hsoX">coordination number</a> of the charged carbon: three in the <a href="/facts/Carbenium_ion/vwRVNmxp">carbenium ions</a> and five in the <a href="/facts/Carbonium_ion/VYlBArVA">carbonium ions</a>. Among the simplest carbocations are the <a href="/facts/Methenium/NJfuh8s8">methenium</a> CH+3 (a carbenium ion), <a href="/facts/Methanium/r1yKLvjh">methanium</a> CH+5 (a carbonium ion), acylium ions RCO+, and <a href="/facts/Vinyl_cation/3rIUACwt">vinyl</a> C2H+3 cations.
Until the early 1970s, carbocations were called carbonium ions. This nomenclature was proposed by <a href="/facts/George_Andrew_Olah/yn3favWM">G. A. Olah</a>. Carbonium ions, as originally defined by Olah, are characterized by a <a href="/facts/Three-center_two-electron_bond/1etgQjYh">three-center two-electron</a> delocalized bonding scheme and are essentially synonymous with so-called '<a href="/facts/Non-classical_carbocation/6SYkhLrm">non-classical carbocations</a>', which are carbocations that contain bridging C–C or C–H σ-bonds. However, others have more narrowly defined the term 'carbonium ion' as formally protonated or alkylated alkanes (CR+5, where R is H or alkyl), to the exclusion of non-classical carbocations like the <a href="/facts/Norbornyl_cation/6SYkhLrm">2-norbornyl cation</a>.

Carbocation open-in-new

Carbocation