Question

Write the equations for the preparation of ethyl chloride using

1. Hydrogen halide
2. ethene
3. Thionyl chloride

Which of these methods is preferred and why?

Answer 1

1. Hydrogen halide:
   \[\ce{\underset{\text{Ethanol}}{CH3CH2 - OH + HCl} ->[anhydrous][ZnCl2] \underset{\text{Ethyl chloride}}{CH3CH2 - Cl} + H2O}\]
2. Ethene:
   \[\ce{\underset{\text{Ethene}}{CH2 = CH2} + HCl -> \underset{\text{Ethyl chloride}}{CH3 - CH2 - Cl}}\]
3. Thionyl chloride:
   
4. The preparation of ethyl chloride using thionyl chloride will be the most preferred method.
   1. Thionyl chloride reacts with straight-chain primary alcohols to give unrearranged alkyl chloride.
   2. The byproducts (SO₂ and HCl) obtained during the course of the reaction are in a gaseous state thus, there is no need to put extra effort for its separation. Hence, this method is preferred for the preparation of ethyl chloride.