Propionyl chloride (also propanoyl chloride) is the organic compound with the formula CH<sub>3</sub>CH<sub>2</sub>C(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.
Propionyl chloride is industrially produced by chlorination of propionic acid with phosgene: