| RTECS = SY5600000 | EINECS = 200-870-3 | UNNumber = 1076 | PubChem = 6371 }} | Section2 = | Section3 = | Section7 = | SPhrases = | NFPA-H = 4 | NFPA-F = 0 | NFPA-R = 1 | FlashPt = non-flammable }} | Section8 = }} Phosgene's the chemical compound with the formula COCl2. This colorless gas gained infamy as a chemical weapon during World War I, but it's also a valued industrial reagent and building block in organic synthesis. In low concentrations, its odor resembles freshly cut hay or grass. So… (More on Phosgene)