<unk> , also called Methyl chloride, or simply R-40 or HCC 40, is a chemical compound of the group of organic compounds called haloalkanes. It was once widely used as a refrigerant.  It is a colorless extremely flammable gas with a slightly sweet odor, which is, however, detected at possibly toxic levels.  Due to concerns about its toxicity, it is no longer present in consumer products.
Methyl chloride was first synthesized by the French chemists Jean-Baptiste Dumas and Eugene Peligot in 1835 by boiling a mixture of methanol, sulfuric acid, and sodium chloride.  This method is similar to that used today.
Chloromethane
Ethanol 
Ethanol
Iodomethane
Bromomethane
Diazomethane
Dichloromethane
Chlorobutanol