ABSTRACT
The aerobic oxidation of 5-hydroxymethylfurfural, a versatile biomass-derived chemical, is examined in water with a titania-supported gold-nanoparticle catalyst at ambient temperature (30 °C). The selectivity of the reaction towards 2,5-furandicarboxylic acid and the intermediate oxidation product 5-hydroxymethyl-2-furancarboxylic acid is found to depend on the amount of added base and the oxygen pressure, suggesting that the reaction proceeds via initial oxidation of the aldehyde moiety followed by oxidation of the hydroxymethyl group of 5-hydroxymethylfurfural. Under optimized reaction conditions, a 71% yield of 2,5-furandicarboxylic acid is obtained at full 5-hydroxymethylfurfural conversion in the presence of excess base.
Subject(s)
Dicarboxylic Acids/chemical synthesis , Furaldehyde/analogs & derivatives , Furans/chemical synthesis , Gold/chemistry , Catalysis , Dicarboxylic Acids/chemistry , Furaldehyde/chemistry , Furans/chemistry , Oxidation-Reduction , Temperature , Water/chemistrySubject(s)
Acetic Acid/chemical synthesis , Air , Ethanol/chemistry , Gold/chemistry , Catalysis , Oxidation-ReductionABSTRACT
We present the angular variation of the resonance magnetic fields as well as the angular variation of the linewidths obtained from single-crystal electron paramagnetic resonance spectra of Delta+ [Cr((-)chxn)(3lambda lambda lambda)]3+ (chxn = trans-1,2-cyclohexanediamine) doped into the nitrate salt of the isostructural Rh(III) ion Delta+ [Rh((-)chxn)(3lambda lambda lambda](NO3)3)3.H2O. An analysis of the angular variation of the resonance magnetic fields indicates axial symmetry for the cation. An analysis of the angular variation of the linewidths, on the other hand, reveals that not all the paramagnetic sites have perfect axial symmetry.
