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

Abstract

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, CH 2 =CH−O−C 2 H 5 →CH 3 CHO+C 2 H 4 . The simple bond fission path (2) with the higher critical energy height, CH 2 =CH−O−C 2 H 5 →CH 2 CHO+C 2 H 5 , did not compete with path 1, at least in the temperature region below 1140 K. Ab initio MO calculations were performed on the 3-21 G 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