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The Catalytic Oxidation Of Alcohols And Olefins With Hydrogen Peroxide Using Peroxo Mo And W Complexes

Posted on:2004-11-14Degree:MasterType:Thesis
Country:ChinaCandidate:X Y ShiFull Text:PDF
GTID:2121360092491608Subject:Organic Chemistry
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The oxidation reaction is one of the most frequently used synthetic reactions in laboratory and chemical manufacturing. The hypervalent metal compounds, such as sexivalent chromium compounds, permanganate, etc. are common oxidizing agents for their excellent oxidative ability. However, these oxidants are expensive, especially, chromium compounds are toxic to human and environment. In this age of advocating green chemistry, clean production and atomic economy, those drawbacks have become more and more unacceptable and intolerant. Hydrogen peroxide is considered as a typical green oxidant because water is the sole expected side product. Consequently, hydrogen peroxide as oxidant has attracted considerably attention. But the oxidation activity of hydrogen peroxide using directly is lower, so the main aim and task of this field is to look for the active and effective catalyst including co-catalyst system. The previous research shows that the Peroxotungstate and Peroxomolybadate have more effective catalytic ability to the oxidation reaction using hydrogen peroxide as oxidant. All the work included this dissertation are based on the idea mentioned above.In the second section, we described the oxidation of cyclohexanol to cyclohexanone with 30% aqueous hydrogen peroxide by using peroxotungstate complexes formed in situ from sodium tungstate dihydrate and various bidentate organic ligands as the catalysts without organic solvents, halide and phase transfer catalyst. The influence of 13 ligands on the oxidation was investigated. The maximum yields of cyclohexanone were obtained when using 1,10-phenanthroline (96%) and oxalic acid (95%) as the ligands. Very good yields (around 90%) were also obtained for the instances of salicylic acid, 3,5-dibromosalicylic acid, and 8-hydroxylquinoline as ligands. A research to improve the reaction condition using cheap oxalic acid as the ligand indicated that the optimum condition is that the reaction mixture in a molar ratio of cycohexanol, tungstate dihydrate, oxalic acid and 30% H2O2 of 100:2:2:120 was stirred at 85-90℃ for 12 oxalic acid as the ligand indicated that the optimum condition is that the reaction mixture in a molar ratio of cycohexanol, tungstate dihydrate, oxalic acid and 30% H2O2 of 100:2:2:120 was stirred at 85-90℃ for 12 hours.DABCO can extract dianion from the aqueous containing monoanion and dianion. The basic reason is that DABCO possesses two positive charges, which make up double identification center that shows special identifiable ability. In the point of electrostatic attraction, it is obvious that the connection between the bivalent cation and dianion is so closely that bivalent cation in the organic layer can extract dianion in the water layer easily. This principle was applied to the peroxomolybate and pcroxotungstate of dianion and organic complexes. The peroxo anion portable active oxygen can be extracted to organic layer effectively. According to this thoughts, the catalytic oxidation was prospected to be carried out perfectly in water-oil two phase system.In third section, eleven novel kinds of bis-quaternary phosphonium (ammonium) salts of peroxotungstate and peroxomolybdate have been synthesized and character! -zed by elemental analysis, IR and Raman spectroscopy. Their catalytic properties in oxidation of cyclohexanol, benzyl alcohol, the derivatives of benzyl alcohol and cyclohexene were investigated with aqueous 30% hydrogen peroxide without organic solvent, halide and phase transfer catalytst. The results show that the bis-quaternary phosphonium peroxotungstates have excellent catalytic ability to the oxidation reaction of benzyl alcohol, cyclohexanol and cyclohexene by hydrogen peroxide under moderate condition. However, the catalytic ability of bis-quaternary phosphonium and ammonium peroxomolybadates is less than that of peroxotungstates. The highest yield of benzaldehyde, benzyl acid, cyclohexanone and adipic acid is 93.89%. 93.04%, 92.70% and 86.16% respectively.
Keywords/Search Tags:Peroxotungstate, peroxomolybadate, bis-quaternary phosphonium, bis-quaternary ammonium, clean catalytic, hydrogen peroxide, cyclohexanol, benzyl alcohol, cyclohexene
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