Alkeeneiden

Alkeeneiden, the Finnish term for alkenes, denote a class of unsaturated hydrocarbons defined by the presence of one or more carbon–carbon double bonds. They are fundamental building blocks in organic chemistry and occur in a wide range of natural and industrial contexts. For acyclic alkeeneiden, the general formula is CnH2n (n ≥ 2). Cycloalkenes have the formula CnH2n−2. The carbon–carbon double bond restricts rotation, giving rise to geometric isomerism (cis/trans or E/Z) in many alkeeneiden, especially when each carbon of the double bond bears two different substituents.

Chemically, alkeeneiden are more reactive than alkanes due to the π bond. They readily undergo addition reactions across the double bond, including hydrogenation, halogenation, hydrohalogenation, and hydration. They also polymerize under suitable conditions to form polymers such as polyethylene and polypropylene, when used as monomers. Substituted and conjugated alkeeneiden display diverse reactivity patterns and are central to many synthetic routes in chemistry.

Occurrence and production are broad. Ethene (ethylene) and propene (propylene) are among the most important alkeeneiden in industry, produced mainly by steam cracking of naphtha or gas oil and by catalytic cracking. Ethene is also a plant hormone involved in growth and ripening processes. Alkeeneiden occur in small amounts in nature and as intermediates in petrochemical industries, where they serve as feedstocks for plastics, resins, and a wide range of chemical products.

In summary, alkeeneiden are a key class of reactive hydrocarbons with a characteristic carbon–carbon double bond, enabling versatile chemistry, polymerization, and a central role in both natural processes and industrial synthesis.