Petrochemicals are chemical products made from raw materials of petroleum or other hydrocarbon origin. (Etymologically, the name is incorrect, as the Greek root petro- means "rock"; theoretically 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).

The two main classes of petrochemical raw materials are olefins (including ethylene and propylene) and aromatics (including benzene and xylene isomers), both of which are produced in very large quantities. At oil refineries, olefins are produced mainly from hydrocarbons by chemical cracking such as steam cracking and by catalytic reforming. At oil refineries, aromatic hydrocarbons are mainly produced by catalytic reforming or similar processes. From these basic building blocks is made a very wide range of chemicals and other materials used in industry - monomers, solvents, detergents, and adhesives. From the monomers, polymers or oligomers are produced for plastics, resins, fibers, elastomers, certain lubricants, and gels.

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
• polyethylenes - polymerized ethylene
• ethanol - made by hydration (chemical reaction adding water) of ethylene
• ethylene oxide - sometimes called oxirane; can be made by oxidation of ethylene
• ethylene glycol - from hydration of ethylene oxide or oxidation of ethylene
• engine coolant - contains ethylene glycol
• polyesters - any of several polymers with ester linkages in the backbone chain
• glycol ethers - from condensation of glycols
• ethoxylates
• vinyl acetate
• 1,2-dichloroethane
• trichloroethylene
• tetrachloroethylene - also called perchloroethylene; used as a dry cleaning solvent and degreaser
• vinyl chloride - monomer for polyvinyl chloride
• polyvinyl chloride (PVC) - type of plastic used for piping, tubing, other things
• propylene - used as a monomer and a chemical feedstock
• isopropyl alcohol - 2-propanol; often used as a solvent or rubbing alcohol
• acrylonitrile - useful as a monomer in forming Orlon, ABS
• polypropylene - polymerized propylene
• propylene oxide
• propylene glycol - sometimes used in engine coolant
• glycol ethers - from condensation of glycols
• isomers of butylene - useful as monomers or co-monomers
• isobutylene - feed for making methyl tert-butyl ether (MTBE) or monomer for copolymerization with a low percentage of isoprene to make butyl rubber
• 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
• higher olefins
• 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.
• other higher olefins
• detergent alcohols
• acrylic acid
• acrylic polymers
• allyl chloride -
• epichlorohydrin - chloro-oxirane; used in epoxy resin formation
• epoxy resins - a type of polymerizing glue from bisphenol A, epichlorohydrin, and some amine

• benzene - the simplest aromatic hydrocarbon
• ethylbenzene - made from benzene and ethylene
• styrene made by dehydrogenation of ethylbenzene; used as a monomer
• polystyrenes - polymers with styrene as a monomer
• cumene - isopropylbenzene; a feedstock in the cumene process
• phenol - hydroxybenzene; often made by the cumene process
• acetone - dimethyl ketone; also often made by the cumene process
• bisphenol A - a type of "double" phenol used in polymerization in epoxy resins and making a common type of polycarbonate
• epoxy resins - a type of polymerizing glue from bisphenol A, epichlorohydrin, and some amine
• polycarbonate - a plastic polymer made from bisphenol A and phosgene (carbonyl dichloride)
• solvents - liquids used for dissolving materials; examples often made from petrochemicals include ethanol, isopropyl alcohol, acetone, benzene, toluene, xylenes
• cyclohexane - a 6-carbon aliphatic cyclic hydrocarbon sometimes used as a non-polar solvent
• adipic acid - a 6-carbon dicarboxylic acid which can be a precursor used as a co-monomer together with a diamine to form an alternating copolymer form of nylon.
• nylons - types of polyamides, some are alternating copolymers formed from copolymerizing dicarboxylic acid or derivatives with diamines
• caprolactam - a 6-carbon cyclic amide
• nylons - types of polyamides, some are from polymerizing caprolactam
• nitrobenzene - can be made by single nitration of benzene
• aniline - aminobenzene
• methylene diphenyl diisocyanate (MDI) - used as a co-monomer with diols or polyols to form polyurethanes or with di- or polyamines to form polyureas
• polyurethanes
• alkylbenzene - a general type of aromatic hydrocarbon which can be used as a presursor for a sulfonate surfactant (detergent)
• detergents - often include surfactants types such as alkylbenzenesulfonates and nonylphenol ethoxylates
• chlorobenzene
• toluene - methylbenzene; can be a solvent or precursor for other chemicals
• benzene
• toluene diisocyanate (TDI) - used as co-monomers with diols or polyols to form polyurethanes or with di- or polyamines to form polyureas
• polyurethanes - a polymer formed from diisocyanates and diols or polyols
• benzoic acid - carboxybenzene
• caprolactam
• nylon
• mixed xylenes - any of three dimethylbenzene isomers, could be a solvent but more often precursor chemicals
• ortho-xylene - both methyl groups can be oxidized to form (ortho-)phthalic acid
• phthalic anhydride
• para-xylene - both methyl groups can be oxidized to form terephthalic acid
• dimethyl terephthalate - can be copolymerized to form certain polyesters
• polyesters - although there can be many types, polyethylene terephthalate is made from petrochemical products and is very widely used.
• purified terephthalic acid - often copolymerized to form polyethylene terephthalate
• polyesters