Nucleophilic Aromatic Substitution Reaction Mechanism - Meisenheimer Complex & Benzyne Intermediate

This organic chemistry video tutorial discusses the mechanism of nucleophilic aromatic substitution reactions. The first type involves a resonance stabilized carbanion intermediate known as the meisenheimer complex which is formed whenever the Benzene ring derivative contains a strong electron withdrawing group such as a nitro group which activates the ring toward SnAr reactions. The Benzyne intermediate occurs when there are no strong electron withdrawing groups present. A strong base / nucleophile such as NaNH2 is needed which will produce an aniline derivative. The benzyne intermediate pathway is an elimination-addition reaction where as the pathway that proceeds through the meisenheimer complex is an addition elimination reaction. This video contains plenty of examples and practice problems.