Industrial Importance of Alkenes
Ethylene as Industrial Feedstock
Ethylene is an important monomeric feedstock in the chemical industry. It is used among other things for the production of industrial intermediates. Ethylene is obtained by pyrolysis of naphtha or other hydrocarbons such as ethane or propane. At temperatures between 750°C and 900°C, the pyrolysis of naphtha yields 20 to 30 percent ethylene.and other
Ethylene is used not only as a monomeric raw material for polymerization but also as a starting material for the synthesis of important industrial chemicals, e.g. which is obtained from the reaction of ethylene and acetic acid on exposure to air in the presence of a palladium(II) catalyst and copper(II) chloride .
If water is used instead of acetic acid, the reaction yields vinyl alcohol which almost completely tautomerizes to acetaldehyde. The catalytic production of acetaldehyde from ethylene and water is called the Wacker process.
Vinyl chloride, prepared by chlorination and subsequent dehydrochlorination of ethylene, is the monomeric starting material for the synthesis of the frequently used(PVC). Instead of using expensive chlorine, the chlorination is carried out with hydrogen chloride and copper(II) chloride in the presence of oxygen to yield the desired intermediate 1,2-dichloroethane, which subsequently is converted into vinyl chloride by thermal elimination of hydrogen chloride.
Ethylene oxide (1,2-epoxyethane, oxirane) is synthesized by the oxidation of ethylene with oxygen in the presence of a silver catalyst. Hydrolysis of ethylene oxide yields ethylene glycol.