PdCl2-catalyzed hydrodeoxygenation of 5-hydroxymethylfurfural into 2,5-dimethylfuran at room-temperature using polymethylhydrosiloxane as the hydrogen donor

A facile and mild method for the catalytic production of 2,5-dimethylfuran (DMF) from 5-hydroxymethylfurfural (HMF) was developed, which utilized commercial PdCl2 as the catalyst together with the green, non-toxic and low-cost hydride source, polymethylhydrosiloxane (PMHS). A synergistic effect among hydrogen donor, in situ generated metallic Pd-0 species and acid site HCl in the reaction played a key role in DMF formation. Gratifyingly, the desirable yield of hydrodeoxygenation product DMF as high as 89.7% from HMF was attained at room temperature (298 K) in 0.5 h. Meanwhile, biomass derived sugars also could be converted into DMF in relative high efficiency via a one-pot reaction in the present system. A plausible pathway for the hydrodeoxygenation of HMF into DMF in the present system was also proposed. The study thus highlights a new perspective for a simple, green, and efficient hydrodeoxygenation of biomass derivatives under milder conditions, employing a readily available, inexpensive and practical catalytic system of PdCl2-PMHS-ethanol, but without any external hydrogen supplies and pre-reduction treatments. (C) 2019 Elsevier Ltd. All rights reserved