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Selective allylic oxidation of cyclohexene was investigated over nanostructured CeO2/SiO2 and CeO2–Sm2O3/SiO2 catalysts synthesized by a feasible deposition precipitation method. The CeO2–Sm2O3/SiO2 catalyst showed excellent catalytic efficiency with ~89 % cyclohexene conversion and ~90 % selectivity for allylic products (i.e., 2-cyclohexen-1-ol and 2-cyclohexene-1-one), while only ~50 and ~35 % cyclohexene conversion was observed, respectively, over CeO2/SiO2 and CeO2 catalysts. Systematic characterization of the designed catalysts was undertaken to correlate their catalytic activity with the physicochemical properties using X-ray diffraction (XRD) analysis, Brunauer–Emmett–Teller (BET) surface area measurements, Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and NH3-temperature programmed desorption (TPD) techniques. The results revealed that doping of Sm3+ into the ceria lattice and simultaneous dispersion of resultant Ce–Sm mixed oxides on the silica surface led to improved structural, acidic, and catalytic properties. The better catalytic efficiency of CeO2–Sm2O3/SiO2 was due to high specific surface area, more structural defects, and high concentration of strong acid sites, stimulated by synergistic interaction between various oxides in the catalyst. The cyclohexene conversion and selectivity for allylic products depended on the reaction temperature, nature of solvent, molar ratio of cyclohexene to oxidant, and reaction time. Possible reaction pathways are proposed for selective allylic oxidation of cyclohexene towards 2-cyclohexen-1-ol and 2-cyclohexene-1-one products. SiO2-supported CeO2–Sm2O3 nanocatalyst exhibited outstanding catalytic performance with superior selectivity for allylic products in liquid-phase selective oxidation of cyclohexene under mild reaction conditions.

The oxidation of cyclohexene was studied using nanostructured CeO2, CeO2/SiO2, CeO2-Sm2O3, and CeO2-Sm2O3/SiO2 catalysts. The CeO2-Sm2O3/SiO2 catalyst shows ~ 96% cyclohexene conversion and ~ 91% selectivity to allylic products, namely, 2-cyclohexen-1-one (~ 53%) and 2-cyclohexen-1-ol (~ 38%) owing to favorable redox (oxygen vacancies) and acid sites stimulated by synergistic interactions of dopant (Sm) and support (SiO2) with CeO2. In contrast, only ~ 40, ~ 55, and ~ 78% of cyclohexene conversions were observed, respectively, over CeO2, CeO2/SiO2, and CeO2-Sm2O3 catalysts. With the increase of reaction time, temperature, and molar ratio of cyclohexene/oxidant, the conversion of cyclohexene and the selectivity of 2-cyclohexen-1-one are increased considerably.

Iron(III)-ethylenediaminetetraacetic acid in aqueous methanol offers a simple, environmentally acceptable synthetic tool to oxidize α-hydroxyketones α-diketones with molecular oxygen, in excellent yields and under mild conditions and without any side reactions.

A variety of tertiary nitrogen compounds have been oxidized to corresponding N-oxides in near quantitative yields by molecular oxygen/2-methylpropanal system in the absence of metal catalyst.

A variety of tertiary nitrogen compounds have been oxidized to corresponding N-oxides in near quantitative yields by molecular oxygen/2-methylpropanal system in the absence of metal catalyst.

The Fe(III)-EDTA complex reacts with sulfide ion in a fast electron transfer reaction, oxidising the latter to elemental sulfur and getting itself reduced to Fe(II). The reaction has been developed for the quantitative estimation of sulfide ion by titration against the Fe(III)-EDTA complex, measuring the redox potential of the system. Repeated use of a given quantity of the complex solution by the process of regeneration has been demonstrated. The possibility of its practical application in liquid phase oxidation processes of recovering sulfur from H2S is emphasized.

Metal phthalocyanines have been found to catalyze the oxidation of sulphides to sulphones at room temperature by molecular oxygen (1 atm) in the presence of isobutyraldehyde as sacrificial aldehyde. Among the metal phthalocyanines studied those of Fe(II), Mn(II) and Co(II)tetrasulphonato- showed excellent activity, followed by VO, while those of Ni(II) and Cu(II) were found to be least active for sulfide oxidation. Mn(II)phthalocyanine catalyzed epoxidation of olefins with molecular oxygen - isobutyraldehyde systems is also reported.

Fe(III)-EDTA in aq. MeOH offers a simple environmentally acceptable synthetic tool to oxidize 2,6-di- t -butylphenol to 3,3′,5,5′-tetra- t -butyl-4,4′-diphenoquinone by molecular oxygen with 100% selectivity and several alkyl-substituted hydroquinones to their quinones, in excellent yields, under mild conditions.