Insight to pyrolysis behavior of three aromatic ethers by pyrolysis coupled with single-photon ionization molecular-beam mass spectrometry

The pyrolytic behaviors of three aromatic ethers were investigated by a self-developed pyrolysis coupled with single-photon ionization molecular-beam mass spectrometry at pressure of pyrolysis chamber 3–6 Pa and temperature from 200 °C to 1100 °C. The results showed that the homolysis of C-O/C-C bridged bonds results into the formation of phenyl, benzyl, phenethyl and phenoxyl radicals. The cracking of benzyl and phenoxyl radicals generates cyclopentadienyl radical around 800 °C. The reaction route of cyclopentadienyl radical to methylcyclopentadiene to benzene existed in all three aromatic ethers pyrolysis process, and two reaction paths for the formation of styrene were also observed. Furthermore, a lot of new polycyclic compounds, such as phthalan, naphthalene, biphenylene, fluorene, dibenzofuran, phenanthrene, 9,10-dihydro-phenanthrene and 9-ethylidenefluorene, are formed through dehydrocyclization and rearrangement of partial thermal cracking species. A reasonable thermal cracking pathway was proposed. Partial experimental results were supported by the density functional theory calculation at the B3LYP level.