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Propanoic anhydride

Propanoic anhydride
Systematic name Propanoyl propanoate
Other names Propionic anhydride
Molecular formula C6H10O3
Molar mass 130.14 g/mol
Appearance Clear liquid, with a strong smell similar to vinegar
CAS number [123-62-6]
Density and phase 1.015 g/cm³, liquid
Solubility in water Reacts to give propionic acid
Melting point -42 °C
Boiling point 167 - 170 °C
Viscosity 1.144 cP at ?°C
Dipole moment  ? D
MSDS External MSDS
Main hazards flammable
NFPA 704
Flash point 63 °C
R/S statement R: R34
S: S26-45
RTECS number UF9100000
Related compounds
Related compounds Acetic anhydride
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

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.



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

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


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]


  1. ^ Williams, J. W. Krynitsky, J. A. (1955). "n-Caproic Anhydride". Org. Synth.; Coll. Vol. 3. 
  2. ^
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Propanoic_anhydride". A list of authors is available in Wikipedia.
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