Electrophile
Definition and meaning of Electrophile in chemistry.
An electrophile is a chemical species, an ion or molecule with an electron-deficient atom, that accepts an electron pair from a nucleophile to form a new covalent bond.
In more detail
Electrophiles are Lewis acids: they either carry a formal positive charge (like H+ or a carbocation) or have an atom made electron-poor by a polarized bond or an attached electronegative group (like the carbon of a carbonyl, or Br2 once it is polarized by an approaching pi bond). Because they seek electrons, electrophiles are attacked by electron-rich nucleophiles, driving reactions such as electrophilic addition to alkenes and electrophilic aromatic substitution. Recognizing the electrophilic site in a molecule is central to predicting where a nucleophile will attack in an organic mechanism.
Key facts
| Field | Organic Chemistry |
|---|---|
| Also called | Lewis acid (electron-pair acceptor) |
| Common examples | H+, NO2+, carbocations, carbonyl carbon |
| Reacts with | Nucleophiles |
In the nitration of benzene, concentrated sulfuric and nitric acids generate the nitronium ion, NO2+, a strong electrophile that is attacked by the electron-rich benzene ring to ultimately form nitrobenzene.
Frequently asked questions
Is every electrophile a Lewis acid?
Yes. By definition an electrophile accepts an electron pair to form a bond, which is exactly the Lewis acid definition; 'electrophile' is simply the term organic chemists use when describing that role in a reaction with a nucleophile.
Can a neutral molecule be an electrophile?
Yes. Neutral molecules such as carbonyl compounds or boron trifluoride (BF3) are electrophilic because an atom within them is electron-deficient, even though the overall species carries no charge.