Large scale use of chloromethane is for the production of dimethyldichlorosilane and related organosilicon compounds. These compounds arise via the direct process. The relevant reactions are (Me = CH):
:x MeCl + Si → MeSiCl, MeSiCl, MeSiCl, MeSiCl, ...
Dimethyldichlorosilane (MeSiCl) is of particular value as a precursor to silicones, but trimethylsilyl chloride (MeSiCl) and methyltrichlorosilane (MeSiCl) are also valuable.
Smaller quantities are used as a solvent in the manufacture of butyl rubber and in petroleum refining.
Chloromethane is employed as a methylating and chlorinating agent, e.g. the production of methylcellulose. It is also used in a variety of other fields: as an extractant for greases, oils, and resins, as a propellant and blowing agent in polystyrene foam production, as a local anesthetic, as an intermediate in drug manufacturing, as a catalyst carrier in low-temperature polymerization, as a fluid for thermometric and thermostatic equipment, and as a herbicide.