The Research Of Electrochemical Synthesis Hydrazobenzene Compounds

In this article the author conclude the mechanism of electrochemical synthesis nitrobenzene compounds, then take a series of characteristics about the process of electrochemical reduction o-chloronitrobenzene(o-CNB), which include Cyclic Voltammetry(CV), Fourier Transform Infrared Spectroscopy(FTIR)and High Performance Liquid Chromatography(HPLC). Then the result was used to inference the mechanism of electrochemical reduction o-CNB. At first, o-CNB was reduced to1-chloro-2-nitrobenzene; second,1-chloro-2-nitrobenzene was reduced to1-chlorobenzene hydroxylamine; third, when1-chlorobenzene hydroxylamine was accumulated to a level, it will be condensation with1-chloro-2-nitrobenzene, then generate2,2’-dichloroazoxybenzene(DOB), at last, DOB was reduction to2,2’-dichlorohydrazobenzene(DHB). In these reactions, a important react condition is that before the reaction, all of the reactors must have a efficient adsorption on the surface of the cathode. Then the author uses the mechanism which received previously to direct the synthesis of another similar compound o-nitroanisole, and make choose for catalyst and current to get a good react result. The result show that when catalyst choose PbO and current choose2A, the productivity of2,2’-dimethoxyhydrideazobenzene can reach the highest as82.8%, and the reaction time is9.5h now.In order to reach a better load result of the catalyst which make the catalyst to be well distributed and the particle size of catalyst to be tiny, the author researched three methods about load catalyst. They are coating, electrostatic adsorption and CV surface crystallization. The result shows that when the catalyst was loaded by CV surface crystallization, the catalyst efficiency is best. The productivity of DHB is93%and the reaction time is5.5h now. Simultaneously, the result of catalyst which loaded by CV surface crystallization was characteristic by scanning electro microscope(SEM) and X-ray diffraction(XRD). As the data shows, the particle size of catalyst approch0.5um is smallest when it is loaded by CV surface crystallization and the character of catalyst was not changed. So CV surface crystallization is a effective method for catalyst loaded.At last, the author research the circulate experiment of o-CNB electrochemical reduction and take the catholyte to recycling use. After thirteen times circulate experiment, the author find that the productivity of DHB keeps stable in90%, the mass fraction of NaOH in catholyte keeps stable in15%and the reaction time keeps stable in6h. The result shows that the reaction condition now is suitble for the circulate experiment of electrochemical synthesis DHB. The author tests the property of proton exchange membrane and contrast with the property of proton exchange membrane before circulate experiment, then find that the moisture content and Ion Exchange Capacity of proton exchange membrane have a little decline. From the contrast of the result, we can see that the little decline of property about proton exchange membrane haven’t influence the efficiency of the synthesis reaction. So if the cycle times can be limited, the proton exchange membrane can satisfied the reaction’s condition now.