The allyl radical, also known as the allyl cation, is a molecular species that contains an unpaired electron, making it highly reactive and unstable. This chemical group has several synonyms, including allyl carbocation, 2-propenyl radical, 2-propenyl cation, and CH2=CH-CH2+ ion. Allyl radicals are commonly found in organic reactions, such as polymerization and oxidation. They are also used in the synthesis of various compounds, such as in the production of plastics, solvents, and pharmaceuticals. Despite its chemical instability, the allyl radical is a valuable tool in chemical research and has played a significant role in the development of modern technology.