Propionyl chloride explained

Propionyl chloride (also propanoyl chloride) is the organic compound with the formula CH₃CH₂C(O)Cl. It is the acyl chloride derivative of propionic acid. It undergoes the characteristic reactions of acyl chlorides.^[1] It is a colorless, corrosive, volatile liquid.

It is used as a reagent for organic synthesis. In derived chiral amides and esters, the methylene protons are diastereotopic.^[2]

There have been efforts^[3] to schedule Propionyl chloride as a DEA List 1 Chemical as it can be used to synthesize fentanyl.

Synthesis

Propionyl chloride is industrially produced by chlorination of propionic acid with phosgene:

CH₃CH₂CO₂H + COCl₂ → CH₃CH₂COCl + HCl + CO₂

Notes and References

1. Book: Michael B Smith. Organic Synthesis. 22 November 2016. Elsevier Science. 978-0-12-800807-2. 165.
2. Diastereoselective Aldol Condensation Using a Chiral Oxazolidinone Auxiliary: (2S,3S)-3-Hydroxy-3-phenyl-2-methylpropanoic Acid. James R.. Gage. David A.. Evans. Org. Synth.. 1990. 68. 83. 10.15227/orgsyn.068.0083.
3. https://www.federalregister.gov/documents/2023/10/12/2023-22570/propionyl-chloride