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. 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.

There have been efforts to schedule propionyl chloride as a DEA List 1 Chemical as it can be used to synthesize fentanyl.[United States-centric]

Synthesis

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

CH3CH2CO2H + COCl2 → CH3CH2COCl + HCl + CO2