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Abstract
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An effective heterogeneous nanocatalyst was successfully designed by immobilization of tungstate ions (WO4 2−) onto the modified surface of carbon quantum dots (CQDs) with the 1-aminopropyl-3-methyl-imidazolium chloride ([APMim][Cl]). In this work, for the first time, the synthesized CQDs@IL/Cl−, via a facile one-step hydrothermal method, was used as an adsorbent and stabilizing support for tungstate ions. Characterization of the synthesized nanoparticles (NPs) by various physicochemical techniques illustrated that tungstate ions have been immobilized on the surface of IL-modified CQDs. With this novel nanocatalyst, a variety of primary, secondary alcohols, and other alcohol substrates have been efficiently oxidized to their corresponding aldehydes and ketones in yields of ≥88% with high selectivity (100%). In the presence of CQDs@IL/WO4 2− as a recyclable nanocatalyst, all alcohol substrates without overoxidation to carboxylic acid were oxidized within 2 h, under a temperature of 70 °C with H2O2 as the oxidant. The above catalyst can be readily recycled using a simple extraction and reused consecutive runs under the described reaction conditions without a considerable decrease in the activity and selectivity. In conclusion, this Article offers a novel application for CQD chemistry.
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