Nucleophilic Substitution

• IMFs involved: Ion–dipole, hydrogen bonding, hydrophobic
• Why common: One of the most widespread organic reaction classes. The solvent determines mechanism (S_N1 vs. S_N2), rate (polar protic vs. aprotic), and stereochemistry. The leaving group is solvated by H-bonding/ion–dipole; the nucleophile is caged by solvent.

Examples:

• CH₃Br + OH⁻ → CH₃OH + Br⁻ (S_N2, aqueous)
• (CH₃)₃CBr → (CH₃)₃C⁺ + Br⁻ → (CH₃)₃COH (S_N1, aqueous)
• SNAr reactions (nucleophilic aromatic substitution)
• Glycosidic bond hydrolysis (enzymatic S_N1-like)

Role of IMFs: Solvent H-bonding stabilizes the leaving group and carbocation; ion–dipole solvation cages the nucleophile; hydrophobic effects can accelerate reactions in water.