Oxidized single-walled carbon nanotubes (SWCNs-COOH) as a newcatalyst for the Oxidation of alcohols

Nano-materials are considered as suitable heterogeneous catalysts for manyorganic reactions. Herein oxidized carbon nanotube (SWCNTs-COOH) has been reported as a heterogeneous catalyst, for oxidation of alcohol in EtOH at 700C. The+Y59 reactions proceed smoothly with good to excellent yields, and the SWCNTs-COOH used can be recycled.1. Introduction Compounds containing the ketone or aldehyde functional group are important in organic chemistry. They are common in nature and are often key intermediates in organic synthesis . Useful methods for preparation of ketones include the coupling of acid chlorides with organozinc reagents, addition of organomagnesium reagents to Weinreb amides and the hydration of alkynes. Aldehydes can be prepared by reduction of acid chlorides or esters withcertain metal hydrides or by catalytic hydrogenation. Despite numerous methods forpreparation, the single most important method for preparation of both ketones and aldehydes is the oxidation ketones and aldehydes is the oxidation of alcohols. Alcohols are among the most readily available organic compounds, and therefore, this method for preparation of aldehydes and ketones is extremely usefulOn the other hand, materials with nano-sized tubular structures including carbon and metal have been developed.15 Among the nano-structured, carbon nanotube has been a focus of extensive research due to its chemical stability, large surface area, non-toxicity, small dimensions and remarkable physical properties of these materials.16 Carbon nanotubes have showed their potential in many fields.17-19 Along with our previous research on carbon nanotubes,20-22 we now describe another application for carbon nanotubes. Although SWCNTs-COOH has been considered as a suitable heterogeneous catalyst, there are in our opinion no reports for catalytic activity of SWCNTs-COOH. Hence, in this context, wereported a mild and convenient procedure for protection of carbonyl groups by usingSWCNTs-COOH as catalyst. The major advantages of the SWCNTs-COOH as catalyst are: (1) ease of separation from reaction mixture by filtration; and (2) catalyst recycling.