Ch 8: Nucleophilic Substitution

Chapter 8: Nucleophilic Substitution

Summary

What does the term "nucleophilic substitution" imply ?

A nucleophile is an the electron rich species that will react with an electron poor species
A substitution implies that one group replaces another.

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