Insights into the Benign, Selective Catalytic Oxidation of HMF to HMFCA in Water Using [Mn<sup>IV</sup><sub>2</sub>(μ-O)<sub>3</sub>(tmtacn)<sub>2</sub>]<sup>2+</sup> and Hydrogen Peroxide
J. O. P. Broekman, Peter J. Deuss
Abstract
High Resolution Image Download MS PowerPoint Slide 5-Hydroxymethylfurfural (HMF) is a biobased platform chemical with a lot of potential to be a key chemical in a future chemical industry. Oxidized derivatives of HMF are explored in many emerging chemical products. However, selective oxidation toward 5-hydroxymethyl-2-furan carboxylic acid (HMFCA) is challenging. Furthermore, this conversion has been hardly explored with homogeneous catalysts. We show here the selective oxidation toward HMFCA using the industrially relevant catalyst [Mn IV 2 (μ-O) 3 (tmtacn) 2 ][(X) 2 ] ( Mncat, X = CH 3 COO/PF 6 /SO 4 ). Moreover, this is achieved in water, under mild conditions (room temperature, pH 11), using low loadings of a nonprecious metal catalyst and hydrogen peroxide, reaching TONs of up to 200 mol HMFCA /mol Mncat . We show that the oxidation under these conditions behaves distinctively from the oxidation with Mncat in MeCN and allows selective oxidation of aldehydes in the presence of alcohols. Kinetic and ESI-MS studies were used to study the change in selectivity and to give an explanation for changes in catalytic behavior.