Editing Electrophilic addition

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| date = March 2021
}}{{Short description|Chemical reaction}}
[[Image:Ear.svg|thumb|460px|The overall reaction for electrophilic addition to [[ethylene]].]]
In [[organic chemistry]], an '''electrophilic addition''' ('''A<sub>E</sub>''') reaction is an [[addition reaction]] where a [[chemical compound]] containing a double or triple bond has a [[π bond]] broken, with the formation of two new [[σ bond]]s.<ref>March, Jerry; (1985). Advanced Organic Chemistry reactions, mechanisms and structure (3rd ed.). New York: John Wiley & Sons, inc. {{ISBN|0-471-85472-7}}</ref>

The driving force for this reaction is the formation of an [[electrophile]] X<sup>+</sup> that forms a [[covalent bond]] with an electron-rich, [[Saturated and unsaturated compounds|unsaturated]] C=C bond. The positive charge on X is transferred to the carbon-carbon bond, forming a [[carbocation]] during the formation of the C-X bond.

:[[Image:ElectrophilicAdditionmechanism.svg|Electrophilic addition mechanism]]
In the second step of an electrophilic addition, the positively charge on the intermediate combines with an electron-rich species to form the second covalent bond. The second step is the same nucleophilic attack process found in an [[SN1 reaction|S<sub>N</sub>1 reaction]]. The exact nature of the electrophile and the nature of the positively charged intermediate are not always clear and depend on reactants and reaction conditions.

In all asymmetric addition reactions to carbon, [[regioselectivity]] is important and often determined by [[Markovnikov's rule]]. [[Organoborane]] compounds give anti-Markovnikov additions. Electrophilic attack to an [[aromatic]] system results in [[electrophilic aromatic substitution]] rather than an addition reaction.

== Typical electrophilic additions ==
Typical electrophilic additions to alkenes with reagents are:
* [[Halogen addition reaction|Halogen addition reactions]]: X<sub>2</sub>
* [[Hydrohalogenation]]s: HX
* [[Hydration reaction]]s: H<sub>2</sub>O
* [[Hydrogenation]]s: H<sub>2</sub>
* [[Oxymercuration reaction]]s: mercuric acetate, water
* [[Hydroboration-oxidation reaction]]s: diborane
* the [[Prins reaction]]: formaldehyde, water

==References==
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[[Category:Electrophilic addition reactions| ]]
[[Category:Reaction mechanisms]]