Cyclopentadienic compounds as intermediates in the thermal degradation of phenols. Kinetics of the thermal decomposition of cyclopentadiene

The thermal degradation of phenol and some methylphenols was followed by pyrolysis gas chromatog. An important step in the thermolysis is the decarbonylation of the phenols yielding cyclopentadienic compds. Thermal cracking of cyclopentadiene and its Me deriv., in fact, yield pyrograms similar to those of the phenolic parents. The kinetics of the thermal degradation of cyclopentadiene in the gas phase were studied by means of a tubular flow reactor with continuous feed of reactant. The decompn. reaction obeys second order reaction kinetics; the activation energy is 20.9 kcal/mole. A reaction mechanism is proposed including the dimerization of cyclopentadiene to exo-dicyclopentadiene as the first step. [on SciFinder (R)