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2. CONTENTS Structure and classes of halocompounds Nomenclature Physical properties Preparation of halocompounds Reactions of halocompounds Uses of haloalkanes THE CHEMISTRY OF Organic halide compounds 2

3. Halocompounds: Halocompounds: contain the functional group C-X where X is a halogen (F,Cl,Br or I) The halogen atom may be attached to an aliphatic skeleton - alkyl group; Halogenoalkanes or to a benzene (aromatic) ring Classes of haloalkanes: Classes of haloalkanes: Halogenoalkanes are classified according to the type of carbon atom bearing the halogen into: Primary alkyl halide CH 3 -X and R-CH 2 -X Secondary alkyl halide (R) 2 -CH-X Tertiary alkyl halide (R) 3 -C-X STRUCTURE OF HALOGENOCOMPOUNDS PRIMARY 1° SECONDARY 2° TERTIARY 3°

4. IUPAC namesIUPAC names derived from original alkane with a prefix indicating halogens and their positions. While common names derived from the corresponding alkyl group followed by the name of halogen atom CH 3 -Cl CH 3 -CH 2 -Br (CH 3 ) 2 -CH-F Common Common Methyl Chloride Ethyl bromide Isopropyl fluoride IUPAC IUPAC Chloromethane Bromoethane 2-Fluoropropane Class Class 1° 1° 2° Common Common Cyclohexyl Iodide t-Butyl bromide Methylcyclopentyl chloride IUPAC IUPAC Iodocyclohexane 2-Bromo-2- 1-Chloro-1-methyl methylpropane cyclopentane Class Class 2° 3 ° 3 ° Nomeclature OF HALOGENOALKANES

5. Physical Properties 5 Solubility : All organic halides are insoluble in water and soluble in common organic solvents. Boiling point : The boiling points increases with increasing in molecular weights. Therefore, the boiling points increases in the order F<Cl<Br<I. M.Wbp / °C 1- Chloropropane78.5 47 1- Bromopropane124 71 Boiling point also increases for “straight” chain isomers. i.e. Greater branching = lower boiling points bp / °C 1-bromobutaneCH 3 CH 2 CH 2 CH 2 Br 101 2-bromobutaneCH 3 CH 2 CHBrCH 3 91 2-bromo -2-methylpropane(CH 3 ) 3 CBr 73

6. 1- Direct halogenation of hydrocarbons a) Halogenation of alkanes b) Halogenation of alkenes

7. d) Halogenation of alkyl benzene and aromatic compounds c) Halogenation of alkynes

8. 2- Halogenation of alcohols

9. 3- Reactions of Grignared reagent a) Formation of Grignard reagent b) Reactions of Grignard reagent

10. 4- Reduction of alkyl halides a- Reduction by Znic metal and acids or by metal hydrides b- Reduction by sodium metal (coupling reaction) c- Reduction using lithium dialkyl cuprate

11. USES OF HALOALKANES SyntheticThe reactivity of the C-X bond means that halogenoalkanes play an important part in synthetic organic chemistry. The halogen can be replaced by a variety of groups via nucleophilic substitution. PolymersMany useful polymers are formed from halogeno hydrocarbons Monomer PolymerRepeating unit chloroethene poly(chloroethene) PVC - (CH 2 - CHCl) n – USED FOR PACKAGING tetrafluoroethene poly(tetrafluoroethene) PTFE - (CF 2 - CF 2 ) n - USED FOR NON-STICK SURFACES Chlorofluorocarbons - CFC’s dichlorofluoromethane CHFCl 2 refrigerant trichlorofluoromethane CF 3 Cl aerosol propellant, blowing agent bromochlorodifluoromethane CBrClF 2 fire extinguishers CCl 2 FCClF 2 dry cleaning solvent, degreasing agent All are/were chosen because of their LOW REACTIVITY, VOLATILITY, NON-TOXICITY