Organic chemistry demands much from chlorine, both as an oxidizing agent and in substitution, since it often brings desired properties in an organic compound when substituted for hydrogen, as in one form of synthetic rubber. Chlorine is a respiratory irritant. The gas irritates the mucous membranes and the liquid burns the skin. As little as 3.5 ppm can be detected as an odor, and 1000 ppm is likely to be fatal after a few deep breaths. It was used as a war gas in 1915.
Natural chlorine contains two isotopes.
Sixteen other isotopes and isomers are known. Manufacture of carbon tetrachloride, ethylene and propylene oxides, glycols, trichloroethylene, perchloroethylene, chloroform, vinylidene chloride, polychloroprene, hydrogen chloride, metal chlorides, chloracetic acid, chloral, synthetic glycerine, methyl chlorides, chlorinated benzenes, tetraethyl lead, fluorine compounds, titanium tetrachloride, monochloroacetic acid, phosgene, chloroisocyanuric acid, phosphorus chloride, dichlorobutene, and chlorinated paraffins. Agent used to control biofouling in cooling systems. Fungicidal foot baths, root canal or tooth extraction, irrigation, or wound sterilization. Cleaning dairy equipment.