Please note that the content of this book mainly consists of articles that are available online from Wikipedia or other free sources. Acetyl chloride or acetic acid chloride is the functional chlorine derivative of acetic acid, in which the hydroxy group of the acid is substituted by chlorine. Acetyl chloride is produced by the reaction of calcium chloride with acetic anhydride. Alternatively, it can be obtained by the reaction of acetic acid with phosphorus(III) chloride. The synthesis from acetic acid and thionyl chloride or phosphorus(V) chloride is also possible, but yields are poorer.