Propionic anhydride

Propionic anhydride

Names
IUPAC name Propanoic anhydride
Other names Propanoic acid, anhydride Propanoyl propanoate
Identifiers
Jmol-3D images	Image
SMILES CCC(=O)OC(=O)CC
Properties
Chemical formula	C6H10O3 (CH3CH2CO)2O
Molar mass	130.14 g/mol
Appearance	Colorless liquid
Odor	Pungent, rancid odor
Density	1.015 g/cm3 (20 °C)
Melting point	−42 °C (−44 °F; 231 K)
Boiling point	167–170 °C (333–338 °F; 440–443 K)
Solubility in water	Slowly hydrolyzes
Solubility	Miscible with chloroform, diethyl ether, ethanol, isopropanol, methanol Slightly soluble in CCl4
Vapor pressure	1.36 mm Hg at 25 °C
Hazards
Safety data sheet	Sigma-Aldrich
Flash point	63 °C (145 °F; 336 K)
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	2,360 mg/kg (rat, oral)
Related compounds
Related compounds	Acetic anhydride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Propanoic anhydride or propionic anhydride is an organic compound with the formula (CH₃CH₂CO)₂O.

Properties

Chemical

Propanoic anhydride slowly hydrolyzes in water to propionic acid.

Physical

Propionic anhydride is a colorless liquid, with a strong pungent smell, which is insoluble in water, but slowly hydrolyzes upon contact. It is miscible with most organic solvents.

Availability

Propionic anhydride is sold by chemical suppliers.

In the US, is it classified as a List I compound, due to its use in the illicit manufacturing of fentanyl and its analogues. As such it cannot be acquired by private individuals, and a license is required to purchase and use the compound.

Preparation

Propionic anhydride can be easily prepared by dry distilling a mixture of dry calcium propionate and propionyl chloride.

Alternatively, distilling a mixture propionic acid and oxalyl chloride will produce propionic anhydride, with a yield of 51%.

Propanoic anhydride can also be obtained by dehydration of dry propionic acid using ethenone.

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

Another route is the Reppe carbonylation of ethylene with propionic acid and nickel carbonyl as the catalyst:

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

Projects

• Make esters

Handling

Safety

Propanoic anhydride is strong smelling and corrosive and will cause burns on contact with skin. Vapors can burn the eyes and lungs.

Storage

In closed bottles, away from moisture.

Disposal

Can be neutralized by adding it in a diluted NaOH or KOH solution, which causes it to hydrolyze to propionic acid and finally sodium or potassium propionate, respectively, which is harmless and can be poured down the drain or dumped in soil.

References

Relevant Sciencemadness threads

• propionic anhydride
• proprionic anhydride new rt synthesis