fosgene

Phosgene (chemical formula COCl₂) is a highly toxic and colorless gas with a faint, sweet odor, often compared to newly mown hay or fresh fruit. It belongs to the class of compounds known as carbonyl chlorides and is primarily used in the production of organic chemicals, particularly polycarbonate plastics and polyurethane foams. Phosgene is synthesized industrially through the reaction of carbon monoxide with chlorine, typically in the presence of an activated carbon catalyst.

Due to its extreme toxicity, phosgene poses significant health risks. Inhalation of even small amounts can cause severe respiratory distress, leading to symptoms such as coughing, chest pain, and pulmonary edema. Prolonged exposure may result in fatal outcomes. Historical accounts note its use as a chemical weapon during World War I, where it was deployed in gas attacks due to its ability to linger in the air and cause delayed effects.

Phosgene is highly reactive and decomposes in the presence of moisture, forming hydrochloric acid and carbon dioxide. This property contributes to its instability and necessitates careful handling in industrial settings. Proper ventilation, protective equipment, and strict safety protocols are essential when working with phosgene to minimize exposure risks.

The compound is regulated under international chemical safety agreements, including the Rotterdam Convention, which restricts its trade to countries with adequate safety measures. Research into safer alternatives and improved handling techniques continues to reduce its use in industrial applications.