Superparamagnetic nanoparticles (SPNs) are excellent supports for synthetic catalysts because of their high surface area, superb dispersability, and ability to be rapidly removed from suspensions by magnetic fields. We report here a simple method for immobilizing TEMPO, an air stable organic oxidant, on magnetite (Fe3O4) SPNs. TEMPO is coupled by azide/alkyne click chemistry to a phosphonate linker that is chelated to the Fe3O4 surface. This approach yields particles with excellent catalytic activity for oxidizing 1� and 2� alcohols to aldehydes and ketones under either acidic aerobic conditions with MnII/CuII co-catalysts, or biphasic basic conditions using NaOCl/KBr. The catalystic SPNs can be recycled > 20 times under the acidic conditions and up to eight times under the basic conditions, with good-to-excellent substrate conversions and product selectivities. These results with TEMPO suggest that phosphonates may be good linkers for immobilizing other catalysts for use under neutral or acidic conditions.

TEMPO-coated Fe<sub>3</sub>O<sub>4 </sub>superparamagnetic nanoparticles: A recyclable catalyst for selective oxidation of alcohols

240th National Meeting (2010)

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TEMPO-coated Fe3O4 superparamagnetic nanoparticles: A recyclable catalyst for selective oxidation of alcohols

TEMPO-coated Fe₃O₄superparamagnetic nanoparticles: A recyclable catalyst for selective oxidation of alcohols