Alkyleeniyhdisteet

Alkyleeniyhdisteet, commonly known in English as alkenes or olefins, are unsaturated hydrocarbons characterized by the presence of at least one carbon-carbon double bond in their molecular structure. The general formula for a simple alkene with one double bond is CnH2n. This double bond consists of one sigma bond and one pi bond, making the molecule more reactive than its saturated counterpart, alkanes, which only contain single bonds. The pi bond is weaker and more accessible to attacking reagents, facilitating addition reactions.

Alkenes are widely used as building blocks in the petrochemical industry. For instance, ethene (ethylene) is a fundamental precursor for the production of polyethylene, a versatile plastic used in packaging, films, and containers. Propene (propylene) is another important alkene, used to create polypropylene, another common plastic found in textiles, automotive parts, and household goods. Other alkenes like butenes are used in the production of synthetic rubber and other polymers.

The presence of a double bond also allows for geometric isomerism (cis-trans isomerism) when each carbon atom of the double bond is attached to two different groups. This structural difference can significantly impact the physical and chemical properties of the alkene. Alkenes are typically nonpolar molecules and are insoluble in water but soluble in organic solvents. Their reactivity is primarily dictated by the double bond, undergoing reactions such as hydrogenation, halogenation, hydrohalogenation, and polymerization.