Nucleophiles and Their Role in Reactions
Specification Reference R3.4.1
Quick Notes:
- A nucleophile is a species that donates a pair of electrons to form a new covalent bond.
- It attacks an electrophile (electron-deficient species).
- Can be negatively charged or neutral.
- Common nucleophiles include:
- OH−, CN−, NH3, H2O, Cl−
- Nucleophiles are electron-rich and attracted to electron-poor centres.
Full Notes:
What is a Nucleophile?
A nucleophile is an electron pair donor.
In reactions, a nucleophile donates a lone pair of electrons to its reaction partner (an electrophile) forming a covalent bond.
Characteristics of Nucleophiles
Nucleophiles must have a lone pair of electrons.
They can be negatively charged ions (e.g. OH−, CN−, Cl−) or neutral molecules (e.g. H2O and NH3).
They are attracted to δ+ (partially positive) or electron-deficient atoms in other molecules.
Common Nucleophiles
Nucleophile | Formula | Charge | Notes |
---|---|---|---|
Hydroxide | OH− | Negative | Strong nucleophile (common in substitution) |
Cyanide | CN− | Negative | Attacks carbon atoms; extends carbon chains |
Ammonia | NH3 | Neutral | Lone pair on nitrogen donates electrons |
Water | H2O | Neutral | Weak nucleophile |
Chloride | Cl− | Negative | Weak nucleophile compared to OH⁻ |
Summary
- Nucleophiles are electron pair donors.
- They can be ions or neutral molecules with lone pairs.
- They attack electrophiles at electron-deficient centres.
- Common nucleophiles include OH−, CN−, NH3, H2O, and Cl−.