Propiolactone

Propiolactone, or β-propiolactone, is an organic compound classified as a lactone containing a four-membered ring. It is a clear, colorless liquid with a slightly sweet odor. It is well soluble in water and miscible with ethanol, acetone, diethyl ether and chloroform. It will slowly react with water to hydrolize to produce 3-hydroxypropanoic acid (hydracryclic acid).

Propiolactone was once widely used in the manufacture of acrylic acid and its esters, but its use has been mostly phased out in favor of safer and less expensive alternatives. Propiolactone is a disinfectant and has been used to sterilize blood plasma, vaccines, tissue grafts, surgical instruments, and enzymes. The principle current use of propiolactone is an intermediate in the synthesis of other chemical compounds.

Propiolactone is "reasonably expected to be a human carcinogen." (IARC 1999)