1-butylene, also known as 1-butene, is a colorless gas that belongs to the alkene family of hydrocarbons. It has the chemical formula C₄H₈ and features a double bond between the first and second carbon atoms. This structure makes it an important building block in the production of various chemicals and plastics. 1-butylene is commonly used in the manufacture of polyethylene, a widely used plastic, and in the production of synthetic rubber. It can also serve as a fuel additive and is involved in various chemical reactions, such as polymerization, to create more complex compounds.