Tsüklopentadieen

Tsüklopentadieen is a colorless liquid with the chemical formula C5H6. It is a cyclic diene with five carbon atoms in a ring and two double bonds. At room temperature, it readily undergoes a Diels-Alder dimerization reaction, forming ditsüklopentadieen. This dimerization is reversible at higher temperatures. Tsüklopentadieen is a flammable substance and has a distinct, somewhat unpleasant odor.

It is an important starting material in organic synthesis, particularly in the production of polymers and fine chemicals. Its ability to form stable cyclopentadienyl anions (Cp anions) makes it valuable in organometallic chemistry. These anions can coordinate to metal atoms, forming metallocene complexes, which have applications in catalysis, materials science, and as fuel additives. Tsüklopentadieen can be obtained from coal tar or by cracking petroleum fractions. It is typically stored and handled in its dimerized form to prevent premature polymerization.