Propionic anhydride

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]

Propionic anhydride

Names
Preferred IUPAC name Propanoic anhydride
Other names Propionic anhydride Propanoyl propanoate
Identifiers
CAS Number	123-62-6 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3186472
ChemSpider	29003 Y
ECHA InfoCard	100.004.218
EC Number	204-638-2
PubChem CID	31263
RTECS number	UF9100000
UNII	E3A2VV18E6 Y
UN number	2496
CompTox Dashboard (EPA)	DTXSID1027007
InChI InChI=1S/C6H10O3/c1-3-5(7)9-6(8)4-2/h3-4H2,1-2H3 N Key: WYVAMUWZEOHJOQ-UHFFFAOYSA-N 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). N verify (what is YN ?) Infobox references

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

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 Administration as a List I chemical under the Controlled Substances Act.^[3]