The preparation of ethyl chloride from ethyl alcohol with thionyl chloride is carried in the presence of pyridine. Here, pyridine is used because:
The thionyl chloride method is preferred over hydrogen chloride or phosphorous chloride method for the preparation of haloalkanes because both the by-products (SO2 and HCl) in this case are gases and escape leaving behind pure chloroalkane. This reaction takes place in the presence of