Unimolecular Thermal Decomposition of Ethyl Vinyl Ether and the Consecutive Thermal Reaction of the Intermediary Product Acetaldehyde: Shock Wave Experiment and ab Initio Calculation

Article abstract of DOI:10.1021/j100154a032

The thermal decomposition of ethyl vinyl ether has been investigated behind reflected shocks over the temperature range from 890 to 1300 K and at a total gas density of approximately 1.0*10^-5 mol cm^-3 by spectroscopic and gas chromatographic analyses.It was confirmed that the main process of the decomposition was the molecular elimination path (1) to form acetaldehyde and ethylene, CH2=CH-O-C2H5 -> CH3CHO + C2H4.The simple bond fission path (2) with the higher critical energy height, CH2=CH-O-C2H5 -> CH2CHO + C2H5, did not compete with path 1, at least in the temperature region below 1140 K.Ab initio MO calculations were performed on the 3-21G level for four conformations of reactant and several transition states and products.The calculated Arrhenius parameters showed that the initial unimolecular step proceeded via the rigid six-center transition state; these parameters were in good agreement with the observed.In addition, evidence for a "chemical activation" effect in the thermal system was presented by the consecutive reactions.