Thermo-kinetic theoretical studies on the homolytic bond cleavages and H-abstractions of 1-methoxy butan-2-one, a keto-ether fuel additive

Abstract

A keto-ether compound, 1-methoxy butan-2-one (MB2O), represents a novel biofuel. Understanding the pyrolysis chemistry of MB2O in its entirety is crucial. H-abstraction reactions by H-atoms and CH₃-radicals are commonly involved in combustion mechanisms. Our study involves the computation of kinetic parameters, emphasizing the contribution of thermodynamic factors to determine the rate coefficient for homolytic bond cleavage reactions and H-abstraction reactions initiated by H atoms and CH₃ radicals. The thermodynamic parameters were obtained using the G3B3 quantum composite method and were compared with the results obtained using the M06-2X/aug-cc-pVTZ method and the CBS-QB3 method. A detailed study was conducted on the potential energy surface (PES) for homolytic bond cleavages and H-abstraction reactions. Canonical transition state theory (CTST) and variational transition state theory (VTST) were used to theoretically determine the rate coefficient values for H-abstraction and homolytic bond cleavage reactions, respectively, in the 500–2000 K temperature range. A key aspect of this work is comparing MB2O to the well-studied biofuel methyl butanoate (MB), its structural isomer. MB2O was found to combust faster than MB. The site-specific reactivity of MB2O was also explored by calculating the various local descriptors such as Fukui functions ($f_r^0$) and local softness ($s_r^0$).