A switchable-oxidative cellulose filter paper bearing immobilized Mn^(III)-salen complex for alcohol oxidation

Abstract

Surface modifications of polysaccharide filter papers can alter their catalytic properties significantly. In particular, polysaccharides have gained increasing interest in the development of heterogeneous catalysts. This wok introduces a new approach to the heterogeneous/ sustainable catalytic system preparation based on a catalytic filter paper modified by silylation followed by immobilization of a Mn(III)-salen complex as a novel “catalytic filtration” or “portable catalysis”. Oxidation of alcohols as well as direct conversion of alcohols to Schiff bases and oximes were performed by filtration and passing the reactants through the modified filter paper. Oxidation of benzyl alcohol in the presence of molecular oxygen and NaOCl, selectively leads to aldehydes and carboxylic acids, respectively. The direct conversion of alcohols to Schiff bases and oximes resulted in the formation of insoluble products on the filter paper. Another advantage of the modified filter paper was its stability and reusability for several times with preservation of the catalytic activity and swellability, which no shrinkage during consecutive wetting–drying cycles was observed. Also, a deep study was conducted over mechanism, reusability/stability, and control experiments of the alcohol oxidation. This study gave new insights into the catalytic propensities of a cellulose filter paper via filtration of reactants.