The Study On Indirect Electrochemical Oxidation To Prepare Anthraquinone Dye Intermediates In Liquid Phase

1,4-naphthoquinone and1-aminoanthraquinone are the significant dye intermediates, both of them are very popular in market. However, the traditional synthesis methods are high pollution and the products are low purity. So it is necessary to find a new way that is pollution-free to synthetize them. In this paper, we think the indirect electrochemical oxidation is a suitable technology that comply the requirement of green chemical, it is safe, pollution-free, low energy consumption and better quality of products.Firstly, many researches have been done to find the best conditions of electrolysis. Through the experiments we found that the film A could be used as diaphragm and the ruthenium-plated titanium mesh be used as electrodes, the distance between two neighbor electrodes was3mm, in the temperature of10℃～15℃, Ce3+was oxidized to Ce4+under the current density of100A/m2, the current efficiency been maintained at80%and the voltage at2.5V after20times of circulation.Researched the synthesis of1,4-naphthoquinone, we changed the factors such as the initial concentration of Ce4+, solvent, the rate of charge, reaction temperature, reaction time one by one to discuss the influence on the production rate and purity. Finally, we confirmed the rational and feasible oxidizing conditions:Naphthalene was used as the raw material and1,2-dichloroethane as the solvent, the initial concentration of Ce4+was0.50mol/L, the mole ratio of Ce4+to naphthalene was7:1,the reaction was kept stirring for1.0hour at the temperature of50℃. The product was characterized by HPLC,1H-NMR and MS, it was reported that we got the1,4-naphthoquinone. The productivity was above96%, the purity was99%. The content of ash was lower than0.1%, so the quality achieved the level of the import product.In the researches of1-aminoanthraquinone, the synthesis of5-nitro-1,4-naphthoquinone was studied firstly. We changed the parameters such as the initial concentration of Ce4+, solvent, the rate of charge, reaction temperature and reaction time to optimize the synthesis conditions, the results showed as follow:1-nitronaphthalene was used as raw material and petroleum ether as solvent, the initial concentration of Ce4+was1.00mol/L, the mole ratio of Ce4+to1-nitronaphthalene was9:1, the reaction was kept stirring for1.4hours at the temperature of70℃. The product was characterized by HPLC,1H-NMR and MS, it was reported that we got the5-nitro-1,4-naphthoquinone. The productivity was above76%, the purity was98%. Then5-nitro-1,4-naphthoquinone reacted with1,3-butadiene, methanol was used as a solvent, after the reactant stirred for24hours under the temperature of90℃in a autoclave,5-nitro-1,4-naphthoquinone was totally transformed into5-nitro-1,4,4a,9a-tetrahydroanthraquinone. At the last step5-nitro-1,4,4a,9a-tetrahydroanthraquinone was reduced by urea in N-methyl-pyrrolidone, the reaction was refluxed for4.0hours at160℃-170℃. The product was characterized by HPLC,’H-NMR and MS, it was reported that we got the1-aminoanthraquinone. The productivity is above96%, the content of carbonization impurity is about30%. So the synthesis of1-aminoanthraquinone doesn’t meet the requirement of industrialization because of the low purity.