Polyoxometalate-based Ionic liquid as thermoregulated and environmentally friendly catalyst for starch oxidation

Abstract A new kind of polyoxometalate (POM) ionic liquid ([(CH 3 ) 3 NCH 2 CH 2 OH] 5 PV 2 Mo 10 O 40 ) (abbreviated as Ch 5 PMo 10 V 2 O 40 ) has been synthesized by a precipitation/ion exchange method with choline chloride and H 5 PMo 10 V 2 O 40 as precursors. The produced salt turned out to be an original ionic liquid (IL) catalyst and exhibited a novel switchable property based on temperature variation. In this regard, it refers to a thermoregulated feature that elevated temperature leads to the miscibility of catalyst and substrate. As decreasing the temperature, the catalyst precipitates and becomes heterogeneous form to be separated automatically from the reaction mixture. The combination of POMs with choline chloride was also proved to be effective in catalyzing the oxidation of starch, which showed higher or nearly identical performance with traditional catalysts, such as FeSO 4 . Results demonstrated the catalyst was easily separated from the products and the retrieved Ch 5 PMo 10 V 2 O 40 could be repeatedly used without appreciable loss of its performance, which highlighted the practical application of this important biomass.