Synthesis Of Phenanthrenequinone By Electrochemical Oxidation

Phenanthrenequinone is a product after phenanthrene is oxidated. It is a new high efficiency and low toxicity pesticide and an important intermediate. It has very extensive applications. Its keen demand makes demand exceed supply in the market at home and abroad.There have been much researches about synthesis of phenanthrene- quinone all the time. But at present, great tonnage production do not come true because of technic, cost, pollution and so on. Investigation of synthesis of phenanthrenequinone at home and abroad was overviewed in this thesis. The research actuality of this task was known. ; The methods of high valency metal salts are the characteristics of simple operation, easy control and higher yield, but the prices of oxidants are expensive,the pollution of waste residures is severious. The prices of oxidants are cheap for peroxide methods and it has no pollution, but production process is complex, instability and easy explosion. The others have toxicity, and are not fit for industrialization. In PTC-RuO4-NaClO method, the catalyst and organic solvent may be recovered and reused, and the yield is highness, but it is only fit for high purity phenanthrene. For crude phenanthrene, the result is not too good because of the effect of residure cumulation. The disadvantage of gas phase catalysis and oxidation is no a good selectivity. At present, a good selectivity catalyst is not found. Considering these problems of synthesis of phenanthrenequinone, a new technic of low cost and no pollution was brought forward in this thesis.Organic electrosynthesis is one of the high-speed developing organic synthesis techonologys. Its characteristics are good selectivity, high purity product, simple technology and no pollution. There are many reports about organic electrosynthesis, but reports about oxidation of phenanthrene for the preparation of phenanthrenequinone by electrosynthes have not been foundso far. The task will research synthesis of phenanthrenequinone by indirect electric oxidation.The purification of crude phenanthrene by using potassium hydroxide- precipitated, component solvent precipitation and melting point are studied in the first part of the thesis, and the purity of the product is analysed qualitatively and quantitatively. The results indicate that the component solvent precipitation is a good method, the purity increasing from 65.19% to 83.63%, and it can provid the raw materials for the synthesis of phenanthrenequinone. But for the potassium hydroxide precipitation, the purity decreases because of charing of crue phenanthrene.The oxidation of phenanthrene for the preparation of phenanthrene- quinone by indirect electric oxidation was studied in the second part of the thesis. Cr(III) is oxidated to Cr(VI) by bielectrode system and constant current electrolysis mode at acidic condition. Then the oxidation liquid and phenanthrene are mixed according to certain proportion, phenanthrene is oxidatated to phenanthrenequinone at stirring. At first, electricoxidation of Cr(III) was studied, the chief factors of this technology was discussed, and the optimum processing condition was found by orthogonal design as follows: reaction time 4h, concentration of sulfuric acid in electrolyte 30% and current density 67mA/cm2, the Cr2O72- yield is 95%. Secondly, oxidation of phenanthrene for the preparation of phenanthrene-quinone was studied. Using above oxidation liquid as oxidant, the influences of proportion of phenanthrene and oxidant, reaction temperature, quantity of catalyst and acidity on the produvtivity were investigated. And the optimum processing condition was found by homogeneous design. The result indicate: the synthesis of phenanthrenequinone by indirect electric oxidation, in which process the demand is not strict to phenanthrene purity and the product yield is high to 98.6%, purity is high to 90.8%. Simultaneous, the circulation utilization of electrolyte was studied, having found that decline of electrolysis efficiency is not too obvious when extracted electolyte is reoxidized.In a word, the technology has many advantages such as mild condition, simplicity of operation, reuse of oxidant, low cost andno pollution. So it has better commercialization foreground.