Aerobic alcohol oxidation catalyzed by CuO-rectorite/TEMPO in water

An environmentally benign CuO-rectorite was prepared by calcining the co-precipitation product of Cu 2+ with an acid-activated rectorite at pH 6. It could be well dispersed in water and used as a co-catalyst with TEMPO to selectively aerobically oxidize alcohols to aldehydes. The conversion of most primary benzylic alcohols was very high under optimized conditions. Interestingly, the oxidation protocol also allowed highly selective transformation of benzylic alcohols containing a phenolic hydroxyl group into the corresponding aldehydes. Additionally, very little copper was leached from the catalyst during the catalytic reaction. CuO-rectorite could be reused by centrifugation and washed with acetonitrile and water. At the same time, its catalytic activity remained high.