In a process developed by Celanese and operated in the USA from 1943 to 1980, propane or propane/butane mixtures are oxidized in the gas phase to produce mixtures containing . The noncatalytic, free-radical reaction takes place at 425-460 °C and 7-20 bar. One version of the Celanese butane oxidation process is conducted in the liquid phase. Either oxygen or air can be used as the oxidizing agent. About 15-20% of the hydrocarbon is completely oxidized. The remaining complex reaction mixture contains, besides acetaldehyde, mainly formaldehyde, methanol, acetic acid, n-propanol, methyl ethyl ketone, acetone, and numerous other oxidation products.

After decomposing any peroxide, the separation of the oxidized products takes place in an involved, and therefore costly, combination of extractions and distillations.