There are several methods for preparing haloalkanes:
1) Direct halogenation of hydrocarbons and halogens. The disadvantages are poor selectivity, poor combustion efficiency, and complex products.
2) Addition reaction of alkenes with hydrogen halides.
3) Substitution reaction of alcohols with hydrogen halides.
4) Byproducts of other reactions, such as chloromethane as a byproduct of organosilicon production.