3.1 Introduction3.2 Mechanism of SN2 Reaction3.3 Nucleophile in SN2 Reaction3.4 Leaving Group in SN2 Reaction3.5 Intermolecular versus Intramolecular Reactions3.5.1 Baldwin’s Rules3.6 Mechanism of SN1 Reaction3.7 Leaving Group in SN1 Reaction3.8 Nucleophile in SN1 Reaction3.9 Carbocation Rearrangements3.10 Stereochemistry of SN2 and SN1 Reactions3.11 Role of Solvent in SN2 and SN1 Reactions3.12 Solvation Effect3.13 Effect of Solvent on Rate of Reaction3.13.1 Effect of Solvent on Rate of SN1 Reaction3.13.2 Effect of Solvent on Rate of SN2 Reaction3.14 Benzylic, Allylic, Vinylic and Aryl Halides3.15 Competition between SN2 and SN1 Reactions3.16 Mixed SN1 and SN2 Mechanism3.17 Neighbouring Group Participation3.18 SummaryProblems