Oxidation of Methylidene Groups to Carbonyl Groups
Oxidation of Methylidene Groups to Carbonyl Groups: Industrial Application:
The Wacker process is used in industry to manufacture acetone from ethylene and acetaldehyde from propylene.
Continuous manufacture of acetaldehyde is accomplished by passing a gaseous mixture of ethylene and oxygen at 90-95 through an aqueous solution of 1.78 palladium(II) chloride, 150 copper(II) chloride and 24 copper(II) acetate per liter contained in a packed-column reactor. To reduce the danger of an explosion, the gaseous mixture consists of 84% ethylene and 16% oxygen. A stream of unreacted gas is used to remove the mixture of acetaldehyde and steam from the reactor. Condensation yields 90% or more of the desired product and small amounts of chloracetaldehyde as side product.
Using the same process, acetone can be manufactured in 92 - 94% yield by air oxidation of propylene at 110-120 and 10-14 in the presence of an aqueous solution of palladium(II) chloride and copper(II) chloride. Today, acetone is produced mostly from petrochemicals.
- Oxidation reactor (solution of catalysts reacts with atmospheric oxygen, unreacted air is removed)
- Reaction vessel (propenyl reacts at 110 - 120 , 10-14 )
- Depressurizing column (using a valve to depressurize the reaction mixture, refilling spent volume of catalyst-solution with water, steam distilling and condensing of products)
- Low-temperature distillation column (distillation and subsequent condensation of propylaldehyde ( 49 ) takes place in this column)
- High-temperature distillation column (distillation and subsequent condensation of acetone ( 56 ) takes place in this column, waste water is purified and reused )
Manufacture of other carbonyl compounds (e.g. butanone) on an industrial scale is carried out in a series of steps involving reaction of 80% sulfuric acid with the alkene, hydrolysis of the sulfuric acid ester and catalytical dehydrogenation of the alcohol.