Magnetically Recoverable Heterobimetallic Co₂Mn₃O₈: Selective and Sustainable Oxidation and Reduction Reactions

Abstract

The present work reports an efficient, sustainable, and cost-effective chemical route for gram-scale synthesis of heterobimetallic Co–Mn oxide (Co2Mn3O8) from the redox reaction between in situ-generated zero-valent cobalt nanomaterial and KMnO4 in water. The magnetically recoverable Co2Mn3O8 nanomaterial showed promising catalytic activity and good selectivity (>99%) for the oxidation of alcohols to aldehydes/ketones both in the presence of air and hydrogen peroxide for a variety of alcohols including benzyl, aliphatic, cinamyl, pyridine, and thiophene moieties. The inexpensive Co2Mn3O8 furnishes excellent catalytic activity and chemoselectivity (>99%) for the reduction of a wide range of aromatic and heteroaromatic nitro substrates to corresponding amines and various dyes under relatively milder reaction conditions with high turnover frequency (TOF). The high catalytic performance and durability in the Co2Mn3O8 nanomaterial for both reactions in comparison to their monometallic oxide (MnO2 and Co3O4) is further attributed to the synergistic effects between each component. Easy synthesis, large-scale application, excellent selectivity, effortless separation of the catalyst using an external magnet, and efficient recycling make the catalyst and the protocol economical and sustainable.

Reduction of Nitro Compounds Using 3d-Non-Noble Metal Catalysts

“…Finally, Co-Mn oxide catalysts should be mentioned here, which have been prepared by treatment of in situ synthesized cobalt nanoparticles with aqueous KMnO 4 at 120 °C. They catalyzed the reduction of nitroarenes with NaBH 4 or hydrazine . Co and Mn in the catalytic material were mainly present in the oxidation states +2 and +4, thus affording the composition Co 2 Mn 3 O 8 .…”

“…They catalyzed the reduction of nitroarenes with NaBH 4 or hydrazine. 412 Co and Mn in the catalytic material were mainly present in the oxidation states +2 and +4, thus affording the composition Co 2 Mn 3 O 8 . The authors compared the activity of the catalyst in the reduction of 4-NP with that of MnO 2 and Co 3 O 4 NPs, prepared with the same procedure, noticing a higher activity.…”

Nanoscale Ni–NiO–ZnO Heterojunctions for Switchable Dehydrogenation and Hydrogenation through Modulation of Active Sites

“…However, we were not able to identify any intermediate except reactants and products. Notably, ZN–R promoted hydrogenation of azobenzene under standard reaction conditions failed to produce any product, which confirms that the reaction proceeds through the direct route in the present case (Figure C) . Further, to check the reactivity difference between ZN–R and ZN–O–A-7 , a few initial rate kinetics were monitored under the specified condition mentioned in Figure A.…”

“…Notably, ZN−R promoted hydrogenation of azobenzene under standard reaction conditions failed to produce any product, which confirms that the reaction proceeds through the direct route in the present case (Figure 7C). 67 Further, to check the reactivity difference between ZN−R and ZN−O−A-7, a few initial rate kinetics were monitored under the specified condition mentioned in Figure 8A. Initially, to perform the kinetic experiments through UV−vis, 3 mL of a solution of 4nitrophenol (250 μM) was taken in a UV-cuvette and to it, 300 μL of 5 × 10 −2 (M) NaBH 4 and 3 mg of catalyst were added.…”

Reusable and Highly Active Copper-Based Lacunary-type Polyoxometalate (LPMo-Cu) as an Effective Catalyst for Nitroarene Reduction in Aqueous Solution

“…So, catalytic reduction of nitroaromatic compounds is a hot research topic because not only do they cause severe health hazards, but also, the obtained anilines are significant intermediates for preparing agricultural chemicals, explosives, dyes, pesticides, pharmaceuticals, and rubber chemicals. , Therefore, utilizing different metal-based catalysts for the reduction of nitroarenes has gained remarkable interest. Recently, many researchers have focused on developing environmentally friendly reduction and oxidation systems to preserve our planet from industrial wastes. − Thus, utilizing efficient catalysts is a key point in order to increase both the conversion and selectivity of these processes . In this context, expensive noble metals and, of course, their alloys are the most frequently utilized catalysts. − So, designing cost-effective catalysts working under mild conditions is promising for the efficient hydrogenation of nitroarenes.…”