One carbon-carbon double bond (-C=C-) at least characterizes alkenes, a class of hydrocarbons. Because of this double bond, alkenes have unique chemical characteristics that make them indispensable in a variety of commercial and natural processes.Alkenes are distinguished by their unsaturation, which means that they have fewer hydrogen atoms than equivalent alkanes with the same amount of carbon atoms. Alkenes can easily perform addition reactions across the double bond and establish new chemical bonds because of their unsaturation. Polymerization, hydration, halogenation, and hydrogenation are examples of common reactions. The process of hydrogenation entails adding hydrogen gas (H2) across the double bond, usually with the help of a catalyst like palladium or platinum. Alkenes are changed into alkanes by this process, which essentially saturates the molecule with hydrogen atoms.The process of adding halogen elements (such chlorine or bromine) across a double bond to generate dihalides is known as halogenation. The halogen molecule breaks its bond with the alkene's carbon atoms to produce two new ones as this reaction moves forward via electrophilic addition.Alcohols are created when water (H2O) is added across a double bond, a process known as hydration. For this reaction to proceed effectively, a catalyst—such as sulfuric acid or mercuric sulfate—is frequently needed. Large polymer chains are created during polymerization, which is the process of adding monomer units with double bonds repeatedly. For instance, ethylene (ethene) monomers are polymerized to create polyethylene. In the production of synthetic rubber, plastics, and other materials, this procedure is essential.Alkenes are also important components of biological systems. For example, they are used as building blocks for the production of several important substances, including as steroids, plant hormones, and fatty acids. Furthermore, some alkenes—like ethylene—have signaling properties that control the ripening of fruit and the growth of plants. Alkenes are adaptable substances with a wide range of uses in both biological and industrial environments, to sum up. Because of the carbon-carbon double bond, which gives them a special reactivity, they may undergo a variety of chemical transformations and are hence essential to many processes and products.
