Propionic anhydride

Propanoic anhydride
Names
	IUPAC name Propanoyl propanoate
	Other names Propanoic anhydride
Identifiers
CAS Number	123-62-6 ;
3D model (JSmol)	Interactive image;
ChemSpider	29003;
ECHA InfoCard	100.004.218
PubChem CID	31263;
RTECS number	UF9100000;
CompTox Dashboard (EPA)	DTXSID1027007 ;
	InChI InChI=1S/C6H10O3/c1-3-5(7)9-6(8)4-2/h3-4H2,1-2H3 Key: WYVAMUWZEOHJOQ-UHFFFAOYSA-N; InChI=1/C6H10O3/c1-3-5(7)9-6(8)4-2/h3-4H2,1-2H3 Key: WYVAMUWZEOHJOQ-UHFFFAOYAJ;
	SMILES CCC(=O)OC(=O)CC;
Properties
Chemical formula	C6H10O3
Molar mass	130.14 g/mol
Appearance	Clear liquid, with a strong smell similar to vinegar
Density	1.015 g/cm³, liquid
Melting point	−42 °C
Boiling point	167–170 °C
Solubility in water	Reacts to give propanoic acid
Viscosity	1.144 cP at ?°C
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	flammable
Flash point	63 °C (145 °F; 336 K)
Related compounds
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Propanoic anhydride is an organic compound with the formula (CH₃CH₂CO)₂O. This simple acid anhydride is a colourless liquid. It is a widely used reagent in organic synthesis.

Synthesis

Propanoic anhydride has been prepared by dehydration of propanoic 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.

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.^[2]

^ Williams, J. W. Krynitsky, J. A. (1955). "n-Caproic Anhydride". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 3.
^ Drugs of Abuse Publication, Chapter 2