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What does the term "nucleophilic substitution" imply ?

Nucleophilic substitution reactions occur when an electron rich species, the nucleophile, reacts at an electrophilic saturated C atom attached to an electronegative group (important), the leaving group, that can be displaced as shown by the general scheme:
Nucleophilic substitution at sp3 C
The electrophilic C can be recognised by looking for the polar σ bond due to the presence of an electronegative substituent (esp. C-Cl, C-Br, C-I and C-O)

Nucleophilic substitution reactions are an important class of reactions that allow the interconversion of functional groups.

Of particular importance are the reactions of alkyl halides (R-X) and alcohols (R-OH)

For alcohols, the range of substitution reactions possible can be increased by utilising the tosylates (R-OTs), an alternative method of converting the -OH to a better leaving group.

Nucleophilic Substitution

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organic chemistry © Dr. Ian Hunt, Department of Chemistry University of Calgary