Classification Classification based on hybridization of carbon to which halogen is bonded-alkyl halides (haloalkane), allylic, benzylic, vinylic, aryl halides. Primary, secondary and tertiary alkyl halides.
Nomenclature Nomenclature
Nature of C-X Bond Nature of C X bond.
Methods of Preparation From alcohols- using HCl / ZnCl2, PX3 (Cl, Br), PCl5, SOCl2 – general reactions and examples with R = CH3, C2H5, Halogen exchange method- Finkelstein reaction – general equation and examples with R = CH3, C2H5, X = Cl, Br, Swarts reaction – statement, example.
Physical Properties density, melting point, boiling point, solubility.
Chemical Reactions Reactions of haloalkanes: Nucleophilic substitution reactions: with aqueous KOH / NaOH, alcoholic KCN, alcoholic AgCN, R COOAg, general reactions, examples (R as CH3 and C2H5). Mechanisms – SN1 and SN2 – HO and CH3Cl for SN2, OH and tertiary butyl bromide for SN1 as examples. Trend in reactivity towards SN1 and SN2 – 1°, 2°, 3° haloalkanes and R I, R Br, R Cl, with reasons. Optical isomerism – optical activity, d form (+) and l form ( ) isomers, 6 chirality, enantiomers, racemic mixture, racemisation, examples. Reaction at a chiral carbon – inversion, retention, racemisation . Stereochemistry of 2-bromobutane and 2-bromooctane in SN1 and SN2 reaction, respectively. Elimination reaction – dehydrohalogenation- general reaction, Zaitsev rule – statement, example taking 2-bromopentane. Reaction with metals – organo – metallic compounds – Grignard reagent, (RMgX), general reaction, its preparation fromCH3Br and C2H5Br, importance of dry ether. Haloarenes: Nucleophilic substitution reactions: reasons for haloarenes to be less reactive, replacement of Cl by hydroxyl group in chlorobenzene and nitro substituted chlorobenzenes to compare the reactivity when NO2 group/s are in o- and p- positions . Electrophilic substitution reactions for chlorobenzene – chlorination, nitration, sulphonation, Friedel-Crafts reaction (alkylation, acetylation). Reaction with metals – Wurtz-Fittig reaction – statement – general reaction, example (R= CH3 and C2H5). Fittig reaction – statement, example – formation of biphenyl.
Polyhalogen Compounds Uses and environmental effects of dichloromethane, trichloromethane, tetrachloromethane, iodoform, freons and DDT.