Haloalkanes and Haloarenes
Classification, nomenclature, preparation methods, physical and chemical properties, stereochemistry, reactions and mechanisms of haloalkanes and haloarenes, including nucleophilic substitution, elimination reactions, and polyhalogen compounds
Topics
Introduction and Classification of Haloalkanes and Haloarenes
What haloalkanes and haloarenes are, how halogen substitution creates new compound families, classification by number of halogen atoms (mono, di, poly), and classification by hybridisation of the carbon bearing the halogen including alkyl, allylic, benzylic, vinylic, and aryl halides
Nomenclature and Nature of the C-X Bond
How haloalkanes and haloarenes are named using common and IUPAC systems, naming rules for mono, di, and polyhalogen compounds, gem vs vic dihalides, structural isomers of bromoalkanes, and the polar nature of the carbon-halogen bond with trends in bond length, enthalpy, and dipole moment
Methods of Preparation of Haloalkanes
How haloalkanes are prepared from alcohols using hydrogen halides, phosphorus halides, and thionyl chloride, from hydrocarbons through free radical halogenation and electrophilic addition to alkenes, and by halogen exchange via Finkelstein and Swarts reactions
Preparation of Haloarenes
How haloarenes are prepared by electrophilic aromatic substitution with halogens and Lewis acid catalysts, and by the Sandmeyer reaction through diazonium salt intermediates, including special cases for iodination and fluorination
Physical Properties of Haloalkanes and Haloarenes
Boiling points, melting points, density, and solubility trends in alkyl halides and haloarenes, including the effects of halogen size, chain length, branching, and isomer symmetry
Nucleophilic Substitution Reactions and the SN2 Mechanism
How nucleophiles replace halogens in haloalkanes, the full product table of nucleophilic substitutions, ambident nucleophiles (KCN vs AgCN, KNO₂ vs AgNO₂), the SN2 bimolecular mechanism with backside attack, inversion of configuration, and how steric hindrance controls reactivity
The SN1 Mechanism and Comparing SN1 vs SN2 Reactivity
The two-step SN1 mechanism through carbocation intermediates, why polar protic solvents matter, how carbocation stability drives SN1 rates, the opposite reactivity orders of SN1 and SN2, resonance stabilisation in allylic and benzylic systems, and the universal leaving-group trend across both mechanisms
Stereochemistry of Nucleophilic Substitution Reactions
Optical activity and plane-polarised light, chirality and asymmetric carbon atoms, enantiomers and racemic mixtures, retention and inversion of configuration, why SN2 gives inversion while SN1 produces racemisation, and identifying chiral molecules
Elimination Reactions and Reactions with Metals
Beta-elimination of haloalkanes using alcoholic KOH to form alkenes, Zaitsev's rule for predicting the major product, the competition between elimination and substitution, Grignard reagents and their formation in dry ether, the polar nature of the C-Mg bond, and the Wurtz reaction for carbon chain extension
Reactions of Haloarenes: Nucleophilic Substitution
Why haloarenes strongly resist nucleophilic substitution due to resonance, sp2 hybridisation, phenyl cation instability, and electron-cloud repulsion, the Dow process for converting chlorobenzene to phenol at extreme conditions, activation by electron-withdrawing nitro groups at ortho and para positions, and the Meisenheimer complex mechanism explaining position-dependent reactivity
Electrophilic Substitution in Haloarenes and Reactions with Metals
How haloarenes undergo electrophilic aromatic substitution with ortho-para selectivity due to the halogen's resonance donation despite its deactivating inductive effect, the four classic electrophilic reactions (halogenation, nitration, sulphonation, Friedel-Crafts), why reactivity and orientation are controlled by different effects, and the Wurtz-Fittig and Fittig coupling reactions of aryl halides with sodium in dry ether
Polyhalogen Compounds
Important carbon compounds carrying more than one halogen atom, covering dichloromethane, chloroform, iodoform, carbon tetrachloride, freons, and DDT, along with their uses, health effects, environmental impact, and the chemistry behind chloroform's dangerous oxidation to phosgene