The thermal decomposition of cis-2,6-dimethyl-3,6-dihydro-2H-pyran

Abstract

The pyrolysis of the title compound has been studied in the gas phase, in the temperature range 300–351°C. The decomposition yields acetaldehyde and trans-penta-1,3-diene by a homogeneous process which is kinetically first order and probably unimolecular. The rate constants fit the Arrhenius equation (i). log k/s^–1= 13.91 ± 0.10 –(196 300 ± 1 200 J mol^–1)/RTIn10 (i) Consideration of the energetics of the process as well as the stereospecific nature of the products lead to the conclusion that the decomposition is a concerted process.