Styrenes

Styrenes are a family of aromatic alkenes characterized by a vinyl group attached to a benzene ring. The parent compound, styrene (also called vinylbenzene), has the formula C8H8 and structure C6H5-CH=CH2. The term “styrenes” also covers substituted styrenes in which the benzene ring bears various substituents or the vinyl group is modified.

The styrene skeleton consists of a benzene ring conjugated with a vinyl group. This arrangement makes the molecule reactive toward radical, ionic, and addition reactions. Styrenes are typically liquids at room temperature, have relatively low polarity, and are relatively hydrophobic. They readily undergo polymerization, especially in the presence of radical initiators, and their derivatives can alter polymer properties.

Industrial production of styrene is primarily by dehydrogenation of ethylbenzene over catalysts at high temperature, producing styrene and hydrogen. This route feeds the large global demand for polystyrene and related copolymers. Substituted styrenes (for example, 4-myd, 4-chlorostyrene, or methylstyrenes) are prepared to tailor polymer properties or to serve as monomers for specialty polymers and fine chemicals.

Styrenes are most notable as monomers for polymer synthesis. Radical polymerization of styrene yields polystyrene, a widely used plastic. Copolymers such as styrene-butadiene rubber (SBR), acrylonitrile-styrene (SAN), and acrylonitrile-styrene-acrylate (ASA) broaden applications in tires, adhesives, coatings, and impact-resistant materials. Handling requires care: styrene is flammable and can pose health risks; polymerization inhibitors are used to control runaway reactions.

The discovery of styrene dates to the 1830s, with industrial relevance rising in the 20th century as plastics became ubiquitous.