CH2CH2

CH2CH2 denotes ethene, a hydrocarbon and the simplest alkene. Its molecular formula is C2H4, and its common name is ethylene; the IUPAC name is ethene. The molecule consists of two carbon atoms joined by a carbon–carbon double bond, with each carbon also bonded to two hydrogens, giving a planar, sp2-hybridized structure.

Ethene is a colorless, flammable gas at room temperature and pressure. It has a boiling point of -103.7°C and is less dense than air. The carbon–carbon double bond makes the molecule reactive toward addition reactions, enabling transformations to many derivatives.

Production and role: Industrially, ethene is produced chiefly by steam cracking of hydrocarbons such as ethane and naphtha. It is a major feedstock for the petrochemical industry, used to produce polyethylene and other plastics. In agriculture, controlled release of ethene speeds fruit ripening.

Common reactions and derivatives: Hydrogenation gives ethane; halogenation yields 1,2-dihaloethanes; hydrohalogenation yields ethyl halides; oxidation produces ethylene oxide, a precursor to further derivatives. Polymerization of ethene yields polyethylene, one of the world’s most widely produced polymers.

Safety and regulation: Ethene is flammable and forms explosive mixtures with air. It must be stored away from ignition sources and handled with proper ventilation and pressure controls. In the environment, ethene is reactive and relatively short‑lived, with effects largely tied to its role as a plant hormone and its participation in atmospheric chemistry.