Alkenne

Alkenne are a class of organic compounds characterized by the presence of at least one carbon-carbon double bond. The general formula for an alkene with one double bond is CnH2n, where n is the number of carbon atoms. This formula indicates that alkenes have two fewer hydrogen atoms than their corresponding alkane counterparts, which contain only single bonds. The presence of the double bond significantly impacts their chemical reactivity, making them more reactive than alkanes.

The simplest alkene is ethene (C2H4), also known as ethylene. Other common alkenes include propene (C3H6) and butene (C4H8). The carbon-carbon double bond consists of one sigma bond and one pi bond. The pi bond is weaker and more accessible, making it the primary site of reaction for alkenes. This allows alkenes to undergo addition reactions, where atoms or groups are added across the double bond, breaking the pi bond and forming new single bonds.

Key reactions of alkenes include hydrogenation, where hydrogen is added to form alkanes; halogenation, where halogens like bromine or chlorine are added; and hydration, where water is added to form alcohols. These reactions are fundamental in organic synthesis and are used to produce a wide range of chemicals, including plastics, solvents, and pharmaceuticals. Alkenes also participate in polymerization, a process where many small alkene molecules (monomers) join together to form long chains called polymers, such as polyethylene.