The pyrolysis of anisole (C6H5OCH3) using a hyperthermal nozzle

We have investigated the pyrolysis of anisole (C6H5OCH3), a model compound for methoxy functional groups in lignin. An understanding of the pyrolysis of this simple compound can provide valuable insight into the mechanisms fo r the thermal decomposition of biomass. Our emphasis in this study is the f ormation of polynuclear aromatic hydrocarbons (PAHs) and in particular we i nvestigate the formation of naphthalene. The route to the formation of naph thalene from anisole follows the simple unimolecular decomposition of aniso le, which leads to the phenoxy radical and then cyclopentadienyl radical. T his chemical pathway has been demonstrated before, but the subsequent react ion of two cyclopentadienyl radicals to give naphthalene has only been the subject of theoretical investigations. We have used matrix isolation FTIR s pectroscopy together with photoionization time-of-flight (TOF) mass spectro metry to identify intermediates in this reaction mechanism. Using this tech nique, we have trapped phenoxy and cyclopentadienyl radicals and measured t heir IR spectra. The formation of these species is confirmed in our TOF mas s spectrometer. We have also identified the formation of 9,10-dihydrofulval ene, the adduct from the reaction of two cyclopentadienyl radicals. Finally , we have used molecular beam mass spectrometry (MBMS) and factor analysis to demonstrate the formation of naphthalene from the pyrolysis of anisole. (C) 2001 Elsevier Science Ltd. All rights reserved.