Group Additive Kinetics for Hydrogen Transfer Between Oxygenates.

Hydrogen abstraction reactions involving oxygenates in gaseous phase play an important role in many biomass-related conversion processes. In this work, group additivity is used to provide Arrhenius parameters in a temperature range of 300-2500 K for hydrogen abstractions between oxygenate compounds such as alcohols, ethers, esters, acids, ketones, diketones, aldehydes, hydroxyperoxides, alkyl peroxides, and unsaturated ethers and ketones. The group additive values for Arrhenius parameters of hydrogen transfer reactions of the type O--H--C and O--H--O are derived from CBS-QB3 calculations in the high-pressure limit. From a total set of 118 reactions, 43 group additivity values are determined. Inclusion of an additional 37 corrections accounting for cross-resonance effects in the transition state further improves the accuracy of the model. For a set of 25 ab initio calculated and 60 experimental rate coefficients, group additive modeling reproduces rate coefficients within a mean factor of deviation of ∼3. Hence, the developed group additive models can be reliably used for an accurate and fast prediction of the kinetics of hydrogen abstractions involving oxygenates.