Baeyer-Viiliger Oxidation Of Cyclic Ketones Using Aqueous Hydrogen Peroxide As Oxidant

Baeyer-Villiger oxidation using aqueous hydrogen peroxide as oxidant in organic unit process is considerable interest to the preparation of lactone and ester intermediates in perfumes, agrochemicals, pharmaceuticals etc. The catalytic activity of different catalysts in the Baeyer-Villiger oxidation of cyclic ketones with aqueous hydrogen peroxide as oxidant was studied. The reaction mechanism of Baeyer-Villiger oxidation of cyclic ketones under different catalytic systems was studied.Research progress of Baeyer-Villiger reaction using peracid, dioxygen or aqueous hydrogen peroxide as oxidant was reviewed. The opportunities and challenges remained in the Baeyer-Villiger reaction were elaborated. Significance of the research topic and research contents were summarized.The catalytic activity of transition metal oxides were compared in the Baeyer-Villiger oxidation of 2-heptylcyclopentanone using aqueous hydrogen peroxide as oxidant. The catalytic activity of MoO3 and WO3 was higher than TiO2, Fe2O3, CO3O4, ZnO and ZrO2. The differences in the catalytic activity of the studied transition metal oxides were obviously related to the differences in their catalytic mechanisms. UV/visible absorption spectra were used for detecting the interaction of MoO3/H2O2, MoO3/H2O and MoO3/2-heptylcyclopentanone. The influences of reaction temperature, molar ratio of hydrogen peroxide to 2-heptylcyclopentanone, concentration of aqueous hydrogen peroxide, amount of catalyst and solvents to the Baeyer-Villiger oxidation were studied. The reactivity of cyclic ketones is notably different, the cyclic ketones (2-adamantanone, 2-methyl cyclohexanone) with tertiary carbon bonded to the carbonyl carbon have higher selectivity to the corresponding lactones than those with secondary carbon, the yield of corresponding lactones were higher than 91%. Additionally, the reaction mechanism of Baeyer-Villiger oxidation of cyclic ketones on MoO3 and WO3 was proposed.A metal tin modified diatomaceous earth was prepared, its structure was characterized by IR spectra and X-ray diffraction spectra. The catalytic activity of SnCl2, SnCl4 and tin modified diatomaceous earth were compared in the Baeyer-Villiger oxidation of 2-heptylcyclopentanone using aqueous hydrogen peroxide as oxidant. The catalytic activity of tin modified diatomaceous earth was lower than SnCl2 and SnCl4. the catalytic mechanism in the Baeyer-Villiger oxidation catalyzed by tin modified diatomaceous earth was different from the catalytic mechanism in the Baeyer-Villiger oxidation catalyzed by SnCl2 and SnCl4. The influences of reaction temperature, molar ratio of hydrogen peroxide to 2-heptylcyclopentanone, concentration of aqueous hydrogen peroxide, amount of catalyst and solvents to the Baeyer-Villiger oxidation were studied. The cyclic ketones (2-adamantanone,2-methyl cyclohexanone) with tertiary carbon bonded to the carbonyl carbon have higher selectivity to the corresponding lactones than those with secondary carbon, the yield of corresponding lactones were higher than 76%.The catalytic activity of different Brcpnsted acid were compared in the Baeyer-Villiger oxidation of 2-heptylcyclopentanone to δ-dodecalactone using aqueous hydrogen peroxide as a clean oxidant.12-Tungstophosphoric acid seems to be a rather efficient and highly selective catalyst for the Baeyer-Villiger reaction of 2-heptylcyclopentanone to δ-dodecalactone. The influences of reaction temperature, molar ratio of hydrogen peroxide to 2-heptylcyclopentanone, amount of catalyst and solvents to the Baeyer-Villiger oxidation were studied. The cyclic ketones with tertiary carbon bonded to the carbonyl carbon have higher selectivity to the corresponding lactones than those with secondary carbon, the yield of corresponding lactones were higher than 70%.12-tungstophosphoric acid was immobilized on different clay via impregnation in aqueous solution. For characterization of the catalysts, FT-IR and XRD were employed, which showed that there was no decomposition of the HPW Keggin structure during material preparation. The prepared catalysts were tested in the Baeyer-Villiger oxidation of 2-heptylcyclopentanone using aqueous hydrogen peroxide as oxidant. The 12-tungstophosphoric acid supported diatomaceous earth was found to be the best catalyst, based on high conversion of 2-heptylcyclopentanone (98.3%). It was observed that the catalytic activity increases with the ratio of Al2O3:SiO2 decreases. The influences of reaction temperature, molar ratio of hydrogen peroxide to 2-heptylcyclopentanone, amount of catalyst and solvents to the Baeyer-Villiger oxidation were studied. The cyclic ketones (2-adamantanone,2-methyl cyclohexanone) with tertiary carbon bonded to the carbonyl carbon have higher selectivity to the corresponding lactones than those with secondary carbon, the yield of corresponding lactones were higher than 72%.The salts of 12-tungstophosphoric acid catalysts are prepared with varying potassium content. For characterization of the catalysts, FT-IR and XRD were employed, which showed that there was no decomposition of the HPW Keggin structure during material preparation. The prepared catalysts were tested in the Baeyer-Villiger oxidation of 2-heptylcyclopentanone using aqueous hydrogen peroxide as oxidant. K2.5H0.5PW is the preferred catalyst in the reaction, based on its reusability, environmental benefits and high conversion of 2-heptylcyclopentanone. The influences of reaction temperature, molar ratio of hydrogen peroxide to 2-heptylcyclopentanone, amount of catalyst and solvents to the Baeyer-Villiger oxidation were studied. The cyclic ketones (2-adamantanone,2-methyl cyclohexanone) with tertiary carbon bonded to the carbonyl carbon have higher selectivity to the corresponding lactones than those with secondary carbon, the yield of corresponding lactones were higher than 81%. Additionally, the reaction mechanism of Baeyer-Villiger oxidation of cyclic ketones on K2.5H0.5PW was proposed.A briefly summary and prospect of Baeyer-Villiger oxidation using aqueous hydrogen peroxide as oxidant were given.