Shock tube study of the pyrolysis kinetics of Di- and trimethoxy methane

The high potential of oxymethylene ethers (OMEs) and related compounds as fuels and fuel-additives motivated a multitude of experimental and theoretical investigations on, e.g., dimethoxy methane (DMM), the smallest member of the OME family. The present work adds to this research by providing combined experimental and theoretical rate coefficients for di- and trimethoxy methane (TMM) pyrolysis. For DMM pyrolysis, the branching ratios between the major dissociation pathways remained elusive in recent studies and is elucidated in the present work using four independent sets of shock tube experiments and master equation modeling. For TMM pyrolysis, the present work provides the very first detailed chemical kinetics model. A key consumption reaction of both compounds, DMM and TMM, is the methoxy-induced H-atom migration, which yields methanol and a singlet diradical. While for DMM this reaction is in direct competition to the C–O bond fission reactions, TMM is found to be a prime example for methoxy-induced H-atom migration, as its pyrolysis chemistry is exclusively governed by this reaction. With the present work, the details of DMM pyrolysis are elucidated and the foundation is laid for detailed chemical kinetics modeling of TMM.