Petrochemicals are chemical products made from raw materials of petroleum (hydrocarbon) origin. (With regard to etymology, the name is incorrect, as the Greek root petro- means "rock"; the correct term is oleochemicals, from the Greek root oleo-, meaning "oil".) Although some of the chemical compounds that originate from petroleum may also be derived from other sources such as coal or natural gas, petroleum is a major source of many. This article is mainly intended to discuss organic compounds or materials that are not burned as fuel (see also Petroleum product).
World production of ethylene is around 110 million tonnes per annum, of propylene 65 million tonnes, and of aromatic raw materials 70 million tonnes. The largest petrochemical industries are to be found in the USA and Western Europe, though the major growth in new production capacity is in the Middle East and Asia. There is a substantial inter-regional trade in petrochemicals of all kinds.
The following is a partial list of the major commercial petrochemicals and their derivatives:
ethylene - the simplest olefin; used as a ripening hormone, a monomer and a chemical feedstock
1,3-butadiene - a diene often used as a monomer or co-monomer for polymerization to elastomers such as polybutadiene or a plastic such as acrylonitrile-butadiene-styrene (ABS)
synthetic rubbers - synthetic elastomers made of any one or more of several petrochemical (usually) monomers such as 1,3-butadiene, styrene, isobutylene, isoprene, chloroprene; elastomeric polymers are often made with a high percentage of conjugated diene monomers such as 1,3-butadiene, isoprene, or chloroprene
polyolefins such poly-alpha-olefins which are used as lubricants
alpha-olefins - used as monomers, co-monomers, and other chemical precursors. For example, a small amount of 1-hexene can be copolymerized with ethylene into a more flexible form of polyethylene.