Immobilization of TEMPO Derivatives in Saponite and Use of These Novel Hybrid Materials as Reusable Catalysts

Roben C, Studer A, Hemme WL, Eckert H

Abstract

The letter describes a novel approach for immobilization of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives by cation-exchange reaction of TEMPO ammonium salts in a commercially available saponite. The organic-inorganic hybrid material is readily prepared and characterized by solid-state H-1 NMR spectroscopy. The hybrid material can be used as recyclable catalyst for oxidation of various alcohols. High catalytic activity for up to 10 runs is obtained. Leaching of the nitroxide salt out of the saponite occurs to a small extent. However, original high activity of the hybrid material can be restored by simply reloading the hybrid material with nitroxide salt by cation exchange.