title: Bimolecular decomposition pathways for carboxylic acids of relevance to biofuels.
abstract: The bimolecular thermal reactions of carboxylic acids were studied using quantum mechanical molecular modeling. Previous work1 investigated the unimolecular decomposition of a variety of organic acids, including saturated, α,β-unsaturated, and β,γ-unsaturated acids, and showed that the type and position of the unsaturation resulted in unique branching ratios between dehydration and decarboxylation, [H2O]/[CO2]. In this work, the effect of bimolecular chemistry (water-acid and acid-acid) is considered with a representative of each acid class. In both cases, the strained 4-centered, unimolecular transition state, typical of most organic acids, is opened up to 6- or 8-centered bimolecular geometries. These larger structures lead to a reduction in the barrier heights (20-45%) of the thermal decomposition pathways for organic acids and an increase in the decomposition kinetics. In some cases, they even cause a shift in the branching ratio of the corresponding product slates.
authors.affiliation: National Bioenergy Center, National Renewable Energy Laboratory , 15013 Denver West Parkway, Golden, Colorado 80401, United States.
authors.forename: Jared M
authors.initials: JM
authors.lastname: Clark
authors.forename: Mark R
authors.initials: MR
authors.lastname: Nimlos
authors.forename: David J
authors.initials: DJ
authors.lastname: Robichaud
mesh_terms: D056804:Biofuels; D002264:Carboxylic Acids / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D013696:Temperature
chemical_list: D056804:Biofuels; D002264:Carboxylic Acids