Phosgene

Not to be confused with phosgene oxime.

Phosgene is the chemical compound with the formula COCl₂. Phosgene gas is colorless and was used as a weapon during World War I. It caused most of the deaths related to poison gas during the war.^[source?]

A phosgene tank.

Chemical note

Today, phosgene is used for organic synthesis. Small amounts of phosgene are produced when certain compounds of chlorine and carbon burn or break down.^[1]

Uses

Today, most phosgene is an ingredient in plastics. Phosgene reacts with bisphenol A or similar chemicals (diols) to make polycarbonates.^[1] Polycarbonates are an important class of engineering thermoplastic. They can be found in lenses in eyeglasses.

Phosgene also reacts with amines to make isocyanates, especially toluene diioscyanate (TDI) and methylene diphenyl diisocyanate (MDI).^[source?] These chemical compounds are used to make polyurethanes. These are a class of materials with many different uses, especially foams, fibers, and coatings.

WWII-era poster teaching soldiers how to identify phosgene gas attacks

Safety

Phosgene is a strong poison. As a gas, it is colorless. Humans cannot see phosgene gas until it reaches a concentration of 0.4 parts per million, which is four times the safe amount. Small amounts of phosgene gas smell like freshly cut hay, grass, or May Blossom.^[source?]

Signs of phosgene exposure sometimes appear slowly.^[2] People at risk of exposure may wear badges to identify themselves.^[1]

Sodium bicarbonate can make spills of phosgene harmless. Spills of phosgene gas can be made harmless with a special liquid spray.^[3]

Action

Phosgene damages the proteins in the pulmonary sac of the lungs, where oxygen passes into the bloodstream. This makes it hard for the blood and air to exchange oxygen and carbon. This makes breathing very hard.

Other websites

• Davy's account of his discovery of phosgene
• International Chemical Safety Card 0007
• NIOSH Pocket Guide to Chemical Hazards
• U.S. CDC Emergency Preparedness & Response Archived 2005-10-17 at the Wayback Machine
• U.S. EPA Acute Exposure Guideline Levels
• Regime For Schedule 3 Chemicals And Facilities Related To Such Chemicals Archived 2006-05-15 at the Wayback Machine, OPCW website
• CBWInfo website Archived 2008-12-02 at the Wayback Machine
• Use of Phosgene in WWII and in modern-day warfare Archived 2016-03-13 at the Wayback Machine (Refer to Section 4.C of the article)
• Phosgene -Citizendium