1. Organics: Level 3
Haloalkanes

2. Name used in Haloalkane
Haloalkanes –yr12 recap
Also called ALKYL HALIDES
one hydrogen atom replaced with a halogen (substitution reaction)
Named the same way as alkanes with a prefix for the halogen
The position on the parent chain
Names in alphabetical
Order if more than one
type of halogen
Use prefixes di, tri if more
than one halogen
Atom
Name used in Haloalkane
bromine
bromo
chlorine
chloro
fluorine
fluoro
iodine
iodo

3. Draw and Name: CH3CBr(CH3)CHBrCH3 Parent chain Halogen atoms
Side chain

4. Haloalkanes- yr12 recap

5. Haloalkane properties
Slightly polar molecules
Low polarity slightly soluble in water
MP and BP depend on molar mass and shape of the molecule as these affect the strength of intermolecular bonding
Chloromethane and chloroethane are gases
Most of the other up to C6 are liquid

6. Haloalkane - uses
Uses
Solvents eg tetrachloromethane for drycleaning, 1,1,1 trichloroethane is twink
Chloroform is an anaesthetic
Used as monomers ie chloroethene for PVC, teflon from tetrafluromethane
CFC’s as aerosol propellants but now banned.

7. Haloalkane - preparation
FAST:- Alkene + HX ----> haloalkane (Addition ) Requires heat/Pt
SLOW: Alkane + Halogen( X2) --- haloalkane + HX ( substitution) requires UV light
Alcohol + Lucas Reagent -- haloalkane + H2O zinc chloride catalyst
Alcohol with PCl3, PCl5 SOCl2

8. Haloalkanes- preparation
Also addition reaction
When hydrohalogenation rxn with an alkene occurs,
Remember Markovnikov’s rule
Minor product
Major product

9. Haloalkanes - Elimination
Major product
Minor product

10. Haloalkanes - Elimination
The halogen can also be removed (eliminated) from the haloalkane leaving an alkene behind
The reagent used in this process is KOH or NaOH dissolved in alcohol (not dilute which is used for substitution -> alcohol)

11. Haloalkanes- Substitution
Substitution and elimination are due to the C-X bond that gives the carbon atom in a haloalkane has a slight positive charge, which attracts nucleophiles
These are molecules or ions characterised by having a lone pair of electrons and which seeks a positive centre

12. Haloalkanes – Substitution
Halogen is replaced by a group that is negatively charged or carries a lone pair nucleophile
Hydroxide ion replaces a halogen forming an alcohol (dilute KOH is used)

13. Haloalkanes – Substitution
Using conc ammonia forms an aminoalkane (amine) –NH2 replaces the halogen, require high pressure and conc ammonia to be dissolved in ethanol
1o amine formed can further react with chloroalkane to form 2o aminoalkane