Nucleophile

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Nucleophile

A Nucleophile is a chemical species that donates an electron pair to an electrophile to form a chemical bond in a reaction. Nucleophiles can be ions (such as the chloride ion, Cl-) or molecules (such as ammonia, NH3). Nucleophiles may take part in nucleophilic substitution reactions, which are of prime importance in organic chemistry.

Characteristics[edit | edit source]

Nucleophiles are characterized by the presence of lone pair of electrons and the ability to form a new bond to a hydrogen ion. The charge on the nucleophile can be negative, neutral or positive. The strength of a nucleophile is not determined by charge but by several factors including: polarizability, charge, and orbital type.

Types of Nucleophiles[edit | edit source]

There are several types of nucleophiles:

  • Neutral Nucleophiles: These are nucleophiles which have a neutral charge. They do not have any extra electrons, but they have a lone pair which can be donated. Examples include water, ammonia, and alcohols.
  • Anionic Nucleophiles: These are nucleophiles with a negative charge. They have an extra electron which can be donated and are thus very strong nucleophiles. Examples include: hydroxide, alkoxide, and carboxylate ions.

Nucleophilicity[edit | edit source]

Nucleophilicity refers to the affinity of a nucleophile towards a positive charge. It is often used to compare the affinity of atoms. It is affected by charge, electronegativity, and polarizability.

Nucleophile vs Base[edit | edit source]

While a nucleophile attacks atoms that are electron deficient, a base attacks atoms that are proton rich. The terms nucleophile and base are often used interchangeably in organic chemistry.

See Also[edit | edit source]

References[edit | edit source]


Nucleophile Resources

Contributors: Prab R. Tumpati, MD