Oxygen Bridged Bimetallic CuMoO₄Nanocatalyst for Benzylic Alcohol Oxidation; Mechanism and DFT Study

Abstract

Though concept of oxygen bridged bimetallic catalyst for organic reaction is not well understood. Herein, we have tried to explain the concept by experimental as well as its support by full DFT study. We report here a competent protocol for dehydrogenative oxidation of benzylic alcohol using an oxygen bridged bimetallic CuMoO 4 nano catalyst. Careful demonstration reveals that oxidation is not effective either with mono-metallic Cu (II) or Mo(VI); instead combination of both the metals through the oxygen bridge [CuÀ OÀ Mo] unexpectedly and interestingly catalyzed the reaction efficiently. The new concept is strongly supported by computational DFT study. DFT study reveals dehydrogenative oxidation is preferred at copper centre over molybdenum and aromatic benzyl alcohols are greatly stabilised. Interaction barrier energy of monometallic CuO and MoO 3 catalyst is much higher than bimetallic CuMoO 4 . Hydrogen transfer has larger barrier heights for CuO (31.5 kcal/mol) and MoO 3 (40.3 kcal/mol) than bimetallic CuMoO 4 .

Mechanochemical NaCl–Mediated Synthesis of Porous CuxMo1–xOy Catalyst for Knoevenagel Condensation

“…Metal molybdates are crucial inorganic materials, because of their unique physical and chemical properties. In recent years, molybdate materials have attracted more and more attention, because of the applications in various fields, including industrial catalysis, , energy storage devices, , scintillator materials, gas sensors, , and photoluminescence. , Among the transition-metal molybdates, copper molybdate has demonstrated good catalytic activity in various processes, such as photodegradation, benzylic alcohol oxidation, the combustion of carbon black, the cross-coupling reaction, , the esterification of oleic acid, and ammonia borane hydrolysis. , However, the state-of-the-art copper molybdate catalysts are bulky with limited porosity (<15 m 2 /g), which restricts the performance for heterogeneous catalysis.…”