Cyclopentadiene is a colorless liquid organic compound with the formula C5H6. It consists of a five-membered carbon ring with two double bonds, making it a diene. This compound is known for its reactivity and is often used in the synthesis of various chemicals, including resins and plastics. Cyclopentadiene can be produced through the thermal cracking of petroleum or by the dimerization of butadiene. It has a distinctive odor and is flammable, requiring careful handling. Due to its unique structure, it can participate in various chemical reactions, including Diels-Alder reactions, which are important in organic chemistry.