1. Organic Halogen CompoundsBy
Dr. Nahed Nasser

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

3. STRUCTURE OF HALOGENOCOMPOUNDS
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: Halogenoalkanes are classified according to the type of carbon atom bearing the halogen into:
Primary alkyl halide CH3-X and R-CH2-X
Secondary alkyl halide (R)2-CH-X
Tertiary alkyl halide (R)3-C-X
PRIMARY 1° SECONDARY 2° TERTIARY 3°

4. Nomeclature OF HALOGENOALKANES
IUPAC 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
CH3-Cl CH3-CH2-Br (CH3)2-CH-F
Common Methyl Chloride Ethyl bromide Isopropyl fluoride
IUPAC Chloromethane Bromoethane Fluoropropane
Class ° ° °
Common Cyclohexyl Iodide t-Butyl bromide Methylcyclopentyl chloride
IUPAC Iodocyclohexane Bromo Chloro-1-methyl
methylpropane cyclopentane
Class ° ° °

5. Physical Properties
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.W bp / °C
1- Chloropropane
1- Bromopropane
Boiling point also increases for “straight” chain isomers.
i.e. Greater branching = lower boiling points bp / °C
1-bromobutane CH3CH2CH2CH2Br
2-bromobutane CH3CH2CHBrCH
2-bromo -2-methylpropane (CH3)3CBr

6. Preparation of Halogen Compounds
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. Reactions of Organic Halides
1- Nucleophilic Subtitution Reactions
Nu- = OH, OR, OCOR, NH2, RNH, SH, SR, RC=C, CN, acytilide anion, I-

10. 2- Elimination Reactions:
Alkyl halides can lose HX molecule to give an alkene.
e.g.1
e.g.2
If the haloalkane is unsymmetrical (e.g. 2-bromobutane or 2-bromopentane) a mixture of isomeric alkene products is obtained.
C3H7Br NaOH(alc) ——> C3H H2O NaBr

11. 3- Reactions of Grignared reagent
a) Formation of Grignard reagent
b) Reactions of Grignard reagent

12. 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

13. USES OF HALOALKANES
Synthetic The 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.
Polymers Many useful polymers are formed from halogeno hydrocarbons
Monomer Polymer Repeating unit
chloroethene poly(chloroethene) PVC (CH2 - CHCl)n –
USED FOR PACKAGING
tetrafluoroethene poly(tetrafluoroethene) PTFE (CF2 - CF2)n -
USED FOR NON-STICK SURFACES
Chlorofluorocarbons - CFC’s
dichlorofluoromethane CHFCl2 refrigerant
trichlorofluoromethane CF3Cl aerosol propellant, blowing agent
bromochlorodifluoromethane CBrClF2 fire extinguishers
CCl2FCClF2 dry cleaning solvent, degreasing agent
All are/were chosen because of their LOW REACTIVITY, VOLATILITY, NON-TOXICITY