title: Mechanistic Investigation of Molybdate-Catalysed Transfer Hydrodeoxygenation.
abstract: The molybdate-catalysed transfer hydrodeoxygenation (HDO) of benzyl alcohol to toluene driven by oxidation of the solvent isopropyl alcohol to acetone has been investigated by using a combination of experimental and computational methods. A Hammett study that compared the relative rates for the transfer HDO of five para-substituted benzylic alcohols was carried out. Density-functional theory (DFT) calculations suggest a transition state with significant loss of aromaticity contributes to the lack of linearity observed in the Hammett study. The transfer HDO could also be carried out in neat PhCH2OH at 175 °C. Under these conditions, PhCH2OH underwent disproportionation to yield benzaldehyde, toluene, and significant amounts of bibenzyl. Isotopic-labelling experiments (using PhCH2OD and PhCD2OH) showed that incorporation of deuterium into the resultant toluene originated from the α position of benzyl alcohol, which is in line with the mechanism suggested by the DFT study.
authors.affiliation: Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800, Kgs. Lyngby, Denmark.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Larsen
authors.affiliation: Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800, Kgs. Lyngby, Denmark.
authors.forename: Allan R
authors.initials: AR
authors.lastname: Petersen
authors.affiliation: Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800, Kgs. Lyngby, Denmark.
authors.forename: Johannes R
authors.initials: JR
authors.lastname: Dethlefsen
authors.affiliation: Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800, Kgs. Lyngby, Denmark.
authors.forename: Ayele
authors.initials: A
authors.lastname: Teshome
authors.affiliation: Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800, Kgs. Lyngby, Denmark. pf@kemi.dtu.dk.
authors.forename: Peter
authors.initials: P
authors.lastname: Fristrup
keywords: Hammett; density functional calculations; deoxygenation; homogeneous catalysis; molybdenum