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In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. A nucleophile participates in a chemical reaction by donating electrons to a species known as an electrophile in order to form a chemical bond. Because nucleophiles donate electrons, they are by definition Lewis bases (see acid-base reaction theories). All molecules or ions with a free pair of electrons can act as nucleophiles, although negative ions (anions) are more potent than neutral reagents.
Nucleophiles may take part in nucleophilic substitution, whereby a nucleophile becomes attracted to a full or partial positive charge on an element and displaces the group it is bonded to.
Nucleophilic is an adjective that describes the affinity of a nucleophile to the nuclei, while nucleophilicity refers to the nucleophilic character. Nucleophilicity is often used to compare an atom's relative affinity to another's.
Common examples
In the example below, the oxygen of the hydroxide ion donates an electron to bond with the carbon at the end of the bromopropane molecule. The pair of electrons in the carbon-bromine bond is given up to the bromine, which leaves as the bromide ion Br-:
Carbon nucleophiles
Oxygen nucleophiles
Sulfur nucleophiles
Nitrogen nucleophiles
See also
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