Preparation of Haloalaknes
1. From Alkanes
A. Direct Halogenation (Chlorination)
When methane react with chlorine gas in presence of sunlight, green radical substitution takes place and results in the formation of halogen substituent product.
This method is not used in laboratory to produce haloalkane, but can be used in industries by controlling the reaction.
B. Bromination
Reaction Proceeds in same manner as chlorination.
C. Iodination
Here HI reacted with strong oxidising agent such as concentrate Nitric Acid.
2. From Alkenes
When any unsymmetrical alkene take participate in Markovnikov's Addition Reaction results in the formation of alkene.
According to Markovnikov's Addition Reaction principal product formation always take place by a more stable carbocation.
3. Allylic Substitution Reaction
Reagents:
- Halogen at high temp (400°c to 500°c).
- NBS ( n-Bromosuccinamide) only for Br.
- SO²Cl² (only for Cl).
4. From Alcohol
5. By Halogen Exchange Method
Finkelstein Reaction is used for the preparation of alkyle iodide.
