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Studies On The Synthesis Of Epoxycyclohexane Using Electrochemical Method

Posted on:2004-06-15Degree:MasterType:Thesis
Country:ChinaCandidate:M Q XuFull Text:PDF
GTID:2121360095450297Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
The reaction of epoxidation of cyclohexene is one kind of explorer reaction of epoxidation of olefin, which can conduct us effectively for investigating the reactionof epoxidation of other kind of olefin. Epoxycyclohexane, the production of this reaction, has very active characteristic of reaction and perfect physical performance. It can be used as solvent of resin made of epoxide because of its excellent performance of dissolution and, it is being attached importance gradually for its ability of alcoholysis, hydrolyze,aminating especially for the material to produce Comite which is one kind of new pesticide. It is obvious that this research has significant values in academic and commercial application.The conventional method of producing epoxide is halogen-alcohol method and Halcon method. Halogen-alcohol method causes great waste water, and polluted environment seriously by using Cl2-H2O at low concentration which has been made in advance. While, another method, Halcon, could y may cause explosion by using RCOOH or ROOH as material, and unfits projects with middle/small scale for its large fund needing and complicated process. The epoxidation of olefin using O2 is thought much of for economical oxidant. In this field, some work such as the preparation and token of catalyst, the investigation of mechanism of the reaction, the chose of solvent is being done in the near ten years, but still exists many difficulties. The emphases on the epoxidation of olefin are about the preparation of electrode, the chose of process and the treatment of mediator after synthesizing.To preparation epoxycyclohexane by using Br2/Br- as mediator through indirect electro-synthesis is our aim. Its mechanism is as follow. First, Br2 producing during electrolysis in non-diaphragm cell turns into BrO3- and stores as active bromine; second, BrO3- turns back into Br2 through changing the acidity of mediator during synthesis and 1-bromine, 2-hydroxyl-cyclohexane is the next result; and then, epoxycyclohexane prepares through changing the acidity again at last.Based on the mechanism, the research are divided into two parts, the electrolysis of NaBr and the synthesis of epoxycyclohexane.In the first part, theefficiency of electrolysis can be determined by analyzing the quantity of active bromine in the mediator which is set out by the method of indirect iodine-quantity.With this method, Na2S2O4 is oxidated by iodine what is oxidated by bromine.In the second part, the epoxycyclohexane is determined the nature and the quantity by the method of Gas-chromatogram, in which cyclohexaone is exterior normal substance.During all experiment, the electrolysis is worked in the electrobath made by ourselves and the synthesis in flask with three outlets. Firstly, the electrolysis of NaBr was carefully investigated at constant current in non-diaphragm electrolytic cell. Through discussing effects of all kinds of factors on current efficiency such as the concentration of electrolyte, time of electrolysis, temperature, etc, the optimum conditions were determined. Secondly, the optimization of synthesis of epoxycyclohexane was carried out by reviewing the effects of factors on the yield of epoxycyclohexane through orthogonal tests and single-factor tests. Finally, how to recycle the mediator was discussed simply through stewing the mediator and adsorption the organic composition with active carbon in the mediator.Based on the research work, some conclusions have been made.1. The current efficiency was up to 90% with PbO2/Pb anode and stainless steel cathode during NaBr electrolysis great more than with PbO2/Ti anode and iron cathode.2. The optimization condition of electrolysis : the density of current is 68A/m2, the temperature of electrolysis is 293-303 K, the concentration of electrolyte is 0.625 mol/1, the pH of electrolyte is 6.63, the quantity of Na2Cr2O7 is 3 g/1.3. The current efficiency was greatly influenced by the first pH of electrolyte.4. The current efficiency was also greatly influenced by the quantity of additive Naa...
Keywords/Search Tags:cyclohexene, epoxycyclohexane, indirect electro-synthesis, Br2/Br- electrolyesis
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