Propionic anhydride


Propanoic anhydride is an organic compound with the formula 2O. This simple acid anhydride is a colourless liquid. It is a widely used reagent in organic synthesis as well as for producing specialty derivatives of cellulose.

Synthesis

Industrial route to propionic anhydride involves thermal dehydration, driving off the water by distillation:
Another routes is the Reppe carbonylation of ethylene with propionic acid and nickel carbonyl as the catalyst:
Propionic anhydride has also been prepared by dehydration of propionic acid using ketene:

Safety

Propanoic anhydride is strong smelling and corrosive, and will cause burns on contact with skin. Vapour can burn eyes and lungs.

Legal Status

Due to its potential use as a precursor in the synthesis of fentanyl and fentanyl analogs, propanoic anhydride is regulated by the United States Drug Enforcement Administration as a List I chemical under the Controlled Substances Act.