Thermal dissociation of ethylene glycol vinyl ether

Abstract

The pyrolysis of ethylene glycol vinyl ether (EGVE), an initial product of 1,4-dioxane dissociation, was examined in a diaphragmless shock tube (DFST) using laser schlieren densitometry (LS) at 57 ± 2 and 122 ± 3 Torr over 1200–1800 K. DFST/time-of-flight mass spectrometry experiments were also performed to identify reaction products. EGVE was found to dissociate via two channels: (1) a molecular H atom transfer/C–O scission to produce C₂H₃OH and CH₃CHO, and (2) a radical channel involving C–O bond fission generating ˙CH₂CH₂OH and ˙CH₂CHO radicals, with the second channel being strongly dominant over the entire experimental range. A reaction mechanism was constructed for the pyrolysis of EGVE which simulates the LS profiles very well over the full experimental range. The decomposition of EGVE is clearly well into the falloff region for these conditions, and a Gorin model RRKM fit was obtained for the dominant radical channel. The results are in good agreement with the experimental data and suggest the following rate coefficient expressions: k_2,∞ = (6.71 ± 2.6) × 10²⁷ × T^−3.21exp(−35512/T) s⁻¹; k₂(120 Torr) = (1.23 ± 0.5) × 10⁹² × T^−22.87exp(−48 248/T) s⁻¹; k₂(60 Torr) = (2.59 ± 1.0) × 10⁸⁸ × T^−21.96exp(−46283/T) s⁻¹.