Propanoic anhydride

Propanoic anhydride, also called propionic anhydride, is a simple acid anhydride. With the chemical formula (CH₃CH₂CO)₂O, it is a widely used reagent in organic synthesis.

Synthesis

Propionic anhydride has been prepared by dehydration of propionic acid using ketene:^[1]

2 CH₃CH₂CO₂H + CH₂=C=O → (CH₃CH₂CO)₂O + CH₃CO₂H

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 Agency as a List I chemical under the Controlled Substances Act.^[2]

References

↑ Williams, J. W. Krynitsky, J. A. “n-Caproic Anhydride” Organic Syntheses, Collected Volume 3, page 164ff (1955). http://www.orgsyn.org/orgsyn/pdfs/CV3P0164.pdf.
↑ http://www.dea.gov/pubs/abuse/2-chem.htm

Synthesis