Phosgene is the
chemical compound with the
formula COCl
2. This colorless gas gained infamy as a
chemical weapon during
World War I where it was responsible for about 85% of the 100,000 deaths caused by chemical weapons. It is also a valued industrial reagent and building block in
synthesis of pharmaceuticals and other
organic compounds. In low concentrations, its odor resembles freshly cut hay or grass. In addition to its industrial production, small amounts occur naturally from the breakdown and the
combustion of
organochlorine compounds, such as those used in
refrigeration systems. The chemical was named by combining the Greek words 'phos' (meaning light) and genesis (birth); it does not mean it contains any
phosphorus (cf.
phosphine).