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Propanoic anhydride

Propanoic anhydride

General
Systematic name	Propanoyl propanoate
Other names	Propionic anhydride
Molecular formula	C₆H₁₀O₃
SMILES	?
Molar mass	130.14 g/mol
Appearance	Clear liquid, with a strong smell similar to vinegar
CAS number	[123-62-6]
Properties
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
Structure
Dipole moment	? D
Hazards
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.

Additional recommended knowledge

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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]