Styrene is an organic compound formed by replacing one hydrogen atom in ethylene with a benzene ring. The conjugation between the electrons of the vinyl group and the benzene ring gives styrene its aromatic hydrocarbon characteristics. Its molecular formula is C₈H₈, and its structural formula is C₆H₅CH=CH₂. Naturally present in storax, styrene is a colorless, oily liquid with a characteristic aroma.

Styrene has a melting point of -30.6°C, a boiling point of 145.2°C, a relative density of 0.9060 (at 20/4°C), and a refractive index of 1.5469. Its viscosity is 0.762 cP at 68°F. Although it is insoluble in water, it is soluble in ethanol and ether. Upon exposure to air, styrene gradually undergoes polymerization and oxidation. To inhibit these processes during storage, stabilizers such as hydroquinone or tert-butyl catechol are added at concentrations ranging from 0.0002% to 0.002%. Styrene is an important monomer used in the manufacture of synthetic resins, ion-exchange resins, and synthetic rubber. It can also participate in addition reactions characteristic of olefins.

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Styrene is mainly used as a raw material in the manufacture of polystyrene, synthetic rubber, engineering plastics, and ion-exchange resins. One of its major applications is as a monomer for producing synthetic rubber and plastics, including styrene-butadiene rubber (SBR), polystyrene, and expanded polystyrene (EPS).

Styrene can also be copolymerized with other monomers to produce a variety of engineering plastics. For example, copolymerization with acrylonitrile and butadiene produces ABS resin, which is widely used in household appliances and industrial applications. When copolymerized with acrylonitrile, styrene forms SAN resin, which features high impact resistance and a glossy finish. Copolymerization with butadiene produces SBS, a thermoplastic rubber commonly used as a modifier for polyvinyl chloride (PVC) and polypropylene.

In addition, small amounts of styrene are used as intermediates in the synthesis of fragrances and other chemical compounds. Through chloromethylation, styrene can be converted into cinnamyl chloride, an intermediate used in the production of the non-narcotic analgesic “Qiangtongding,” a preparation containing proheptazine. Styrene is also used as a starting material for synthesizing “Yikeqin,” an antitussive and expectorant related to clobutinol derivatives, and “Weichangning,” an anticholinergic drug containing oxyphencyclimine.