Introduction of Alkenes

In organic chemistry, an alkene is an unsaturated chemical compound containing at least one C=C. The simplest acyclic alkenes, with only one C=C and no other functional groups, form an homologous series of hydrocarbons with the general formula C_n H_2n.

Unsaturated hydrocarbons contain either double or triple bonds. Since the compound is unsaturated with respect to hydrogen atoms, the extra electrons are shared between 2 carbon atoms forming double bonds in alkenes.

The simplest alkene is ethylene (C₂H₄), which has the International Union of Pure and Applied Chemistry (IUPAC) name ethene. Alkenes are also called olefins (an archaic synonym, widely used in the petrochemical industry).

                                                                   Ethene

Propene

Butene

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Manufacture of alkenes

Alkenes are produced by hydrocarbon cracking. Raw materials are mostly natural gas condensate components. Alkanes are broken apart at high temperatures, often in the presence of a zeolite catalyst, to produce a mixture of primarily aliphatic alkenes and lower molecular weight alkanes. The mixture is feedstock dependent and separated by fractional distillation. This is mainly used for the manufacture of small alkenes (up to six carbons).