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The Oxidation Of Cyclohexene To Prepare 1,2-diols Over Molybdenum Oxide And Quaternary Ammonium Salt Catalysts

Posted on:2016-05-08Degree:MasterType:Thesis
Country:ChinaCandidate:B XuFull Text:PDF
GTID:2311330473964696Subject:Chemical engineering
Abstract/Summary:PDF Full Text Request
1,2-cyclohexanediol is an important fundamental chemical feed-stock. It is widely used as feed stock to prepare polyesters, medicines, pesticides, a nd other fine chemicals.This thesis mainly studied the catalytic oxidation of cyclohexene with hydrogen peroxide to prepare 1,2-cyclohexanediol, and developed a new molybdenum oxide-quaternary ammonium salt(alkali) catalyst,which was simple, environmental friendly, and high selectivity.In this investigation, cyclohexene oxidation over molybdenum oxide-quaternary ammonium salt catalysts to prepare 1,2-cyclohexanediol was conducted. This reaction approach offers a inexpensive environmental friendly me thod to synthesize 1,2-cyclohexanediol in high selectivity.Firstly, molybdenium trioxide was used as the major catalyst and quaternary ammonium salt was used as phase transfer catalyst to catalyze the oxidation of cyclohexene in the investigation. The investigation work was focused on the influence of different phase transfer catalysts, reaction temperature, the amount of the catalyst, the dosage of sodium chloride and the solvent dosage of water on the reaction. It was found that quaternary ammonium chloride salts showed relatively higher efficience. Usually, the highest product yields could obtained at 75 ? over different quaternary ammonium chloride phase transfer catalysts. When running reactions at 75 ?, the order of the efficience of quaternary ammonium chlorides according to 1,2-cyclohexanediol yield and selectivity is: didodecyl dimethyl ammonium chloride > didecyl dimethyl ammonium chloride > dimethyl distearyl ammonium chloride > octadearyl dimethyl ammonium chloride > hexadecyl trimethyl ammonium chloride > tetradecyl trimethyl ammonium chloride > dodecyl trimethyl ammonium chloride > trimethyl octyl ammonium chloride. The investigations indicates that at the optimized reaction conditions, the reaction temperature is 75?, the mol ratio of cyclohexene to hydrogen peroxide is 2:1, the phase transfer catalyst is didodecyl dimethyl ammonium chloride, the amount of both Mo O 3 and phase transfer catalyst are 0.400 mmol, and the amount of H2 O is 5.00 g, the 1,2-cyclohexanediol yield and selectivity of 33.8% and 98.9% were obtained. There were also trace cyclohexenol and cyclohexenone formed as by-products.Afterwards, molybdenium trioxide was used as the major catalyst and quaternary ammonium hydroxide was used as the phase transfer catalyst to catalyze the oxidation of cyclohexene in the investigation. When running reactions at 75?, the order of the efficience of quaternary ammonium hydroxide according to 1,2-cyclohexanediol yield is: dimethyl distearyl ammonium hydroxide > didecyl dimethyl ammonium hydroxide > didodecyl dimethyl ammonium hydroxide > tetradecyl trimethyl ammonium hydroxide > octadearyl dimethyl ammonium hydroxide > dodecyl trimethyl ammonium hydroxide > hexadecyl trimethyl ammonium hydroxide > trimethyl octyl ammonium hydroxide.Under the optimized reaction conditions(the reaction temperature is 70?, the mol ratio of cyclohexene to hydrogen peroxide(30.0wt%) is 2:1, the phase transfer catalyst is didodecyl dimethyl ammonium chloride, the amount of both Mo O 3 and phase transfer catalyst are 0.500 mmol, and the amount of H2 O is 5.00 g), the 1,2-cyclohexanediol yield and selectivity of 29.4% and 98.2% were obtained.
Keywords/Search Tags:1,2-cyclohexanediol, cyclohexene, hydrogen peroxide, quaternary ammonium salt, molybdenum trioxide catalyst
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