Cyclooctatetraeeni

Cyclooctatetraene, often abbreviated as COT, is an organic chemical compound with the formula C8H8. It is a cyclic hydrocarbon featuring an eight-membered ring with four alternating double bonds. This structure gives it a unique electronic configuration, distinguishing it from aromatic compounds. Unlike benzene, which is planar and aromatic, cyclooctatetraene is non-planar and exhibits tub-like conformations.

The discovery of cyclooctatetraene is attributed to Richard Willstätter in 1908. His synthesis of this molecule was a significant achievement, as it challenged existing theories about chemical bonding and aromaticity at the time. Cyclooctatetraene is not aromatic in the Hückel sense, as it has 4π electrons, which would be antiaromatic if it were planar. However, its non-planar structure allows it to avoid this unfavorable state.

Cyclooctatetraene is a colorless liquid at room temperature and is generally insoluble in water but soluble in organic solvents. It can undergo various chemical reactions, including addition reactions and polymerization. Its derivatives are of interest in organometallic chemistry and materials science. The compound can be synthesized through several methods, with the Reppe synthesis, involving the cyclization of acetylene under high pressure and temperature in the presence of nickel catalysts, being a notable historical route.