11.3.Methods of Preparation : Alkyl Halides and Aryl Halides- from Alcohols, from Hydrocarbons (a) By Free Radical Halogenations – (b) By Electrophilic Substitution (c) By replacement of Diazonium Group (Sand-Meyer Reaction) (d) By the Addition of Hydrogen Halides and Halogens to Alkenes - By Halogen Exchange (Finkelstein reaction)