Acetone by Dry Distillation of Acetate of Lime

Before the cumene process, acetone was made from "acetate of lime", calcium acetate. Limestone (calcium carbonate) soaked in vinegar gives calcium acetate; when the dry salt is heated it breaks down into calcium carbonate and acetone: Ca(CH₃COO)₂ → CaCO₃ + (CH₃)₂CO. Charles Friedel reported this dry distillation in 1858, and until World War I it was the main commercial way to make acetone. The calcium carbonate is left behind in the retort and the acetone distils over.