Propionic anhydride

Propionic anhydride
Names
	Preferred IUPAC name Propanoic anhydride
	Other names Propionic anhydride; Propanoyl propanoate
Identifiers
CAS Number	123-62-6 ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL3186472;
ChemSpider	29003 ;
ECHA InfoCard	100.004.218
EC Number	204-638-2;
PubChem CID	31263;
RTECS number	UF9100000;
UNII	E3A2VV18E6 ;
UN number	2496
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 (−44 °F; 231 K)
Boiling point	167 to 170 °C (333 to 338 °F; 440 to 443 K)
Solubility in water	Reacts to give propanoic acid
Viscosity	1.144 cP at ?°C
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	flammable
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
Flash point	63 °C (145 °F; 336 K)
Safety data sheet (SDS)	External MSDS
Related compounds
Related compounds	Acetic anhydride Propanoyl chloride
	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

Propionic 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 as well as for producing specialty derivatives of cellulose.^[1]

Synthesis

Industrial route to propionic anhydride involves thermal dehydration of propionic acid, driving off the water by distillation:

2 CH₃CH₂CO₂H → (CH₃CH₂CO)₂O + H₂O

Another routes is the Reppe carbonylation of ethylene with propionic acid and nickel carbonyl as the catalyst:^[1]

CH₂=CH₂ + CH₃CH₂CO₂H + CO → (CH₃CH₂CO)₂O

Propionic anhydride has also been prepared by dehydration of propionic acid using ketene:^[2]

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.^[3]

^ ^a ^b Samel, Ulf-Rainer; Kohler, Walter; Gamer, Armin Otto; Keuser, Ullrich (2005). "Propionic Acid and Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a22_223. ISBN 978-3527306732.
^ Williams, J. W. Krynitsky, J. A. (1941). "n-Caproic Anhydride". Organic Syntheses. 21: 13. doi:10.15227/orgsyn.021.0013{{cite journal}}: CS1 maint: multiple names: authors list (link).
^ Drugs of Abuse Publication, Chapter 2 Archived 2007-12-20 at the Wayback Machine