PHOSGENE – COCl2
Phosgene is an organic chemical compound with the molecular formula COCl2 (Carbonyl dichloride). Phosgene gas is very toxic and dangerous. Even in low concentrations, the colorless COCl2 gas has a characteristic sweetish, putrid smell of damp hay or grass. However, the odor threshold of COCl2 is already far above the permissible exposure limit values.
Due to its poor water solubility, phosgene reaches the pulmonary alveoli directly when inhaled. In contact with water, COCl2 gradually decomposes into CO2 and aggressive HCl (Hydrogen chloride). Furthermore, phosgene reacts with proteins and enzymes in the pulmonary alveoli area inside the lungs. Both processes damage the lungs and lead to pulmonary edema. The symptoms can be delayed for several hours or a few days and can lead to death. This effect characteristic of delayed symptoms poses a particular danger when accidents with phosgene happen, and phosgene was inhaled. The extent of the damage depends less on the concentration itself and more on the amount, dose of substance absorbed. Phosgene is also known as a chemical warfare agent from World War I.
Phosgene COCl2 is an industrial gas, which is mainly used for production of toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI). Both are important precursors in the manufacture process of polyurethanes and polycarbonates. Phosgene is also used as a precursor in the production process of pesticides.
The production of phosgene COCl2 takes place with suitable catalysts and with basic components CO (Carbon monoxide) and Cl2 (Chlorine). To avoid any dangers and risks when transporting or storing phosgene, it is typically produced as required and “on demand” directly in the plant in which it is further processed and consumed.
