olefiny

Olefiny, or olefins, are a class of hydrocarbons defined by the presence of at least one carbon–carbon double bond. The term olefin is older and more common in industrial contexts, while alkene is the preferred IUPAC designation in modern chemistry. Olefins are foundational to the petrochemical industry as both reactive intermediates and monomers for polymer production.

Most olefins are unsaturated hydrocarbons with varying chain lengths. For acyclic monoalkenes, the general formula is CnH2n, though exact formulas depend on branching and ring structures. They exhibit cis–trans (geometric) isomerism when the double bond is internal. Common examples include ethene (ethylene), propene (propylene), and butenes. Terminal olefins have the double bond at the end of the chain, while internal olefins have it within the carbon skeleton.

Olefins participate in a wide range of reactions across the double bond. They readily undergo hydrogenation to form alkanes, halogenation, hydrohalogenation, and hydration to alcohols. They also polymerize to give polyolefins, such as polyethylene from ethene and polypropylene from propene, through various catalytic systems (including Ziegler–Natta and metallocene catalysts). Oxidation and epoxidation are other important transformations for producing diverse functionalized products.

Production and industrial relevance: olefins are primarily derived from petroleum feedstocks via steam cracking or catalytic cracking. Ethene and propene are among the most important olefins, serving as key building blocks for plastics, synthetic fibers, solvents, and numerous chemical intermediates.

Safety and handling: olefins are generally flammable and must be handled with appropriate safety measures to prevent fires and exposures in industrial and laboratory settings.