The Eletrosynthesis Of N-methylhydroxylamine Hydrochloride

Organic electrosynthesis combined organic synthesis with electrochemical technology is a frontier subject.Aiming for green synthesis,it plays an important par't in the development of the green chemical synthesis industry in the future.The nano-TiO2 electrode is a new type of nanometer materials.Due to its good performance for electro-catalytic hydrogenation of unsaturated compounds and electrochemical reduction of nitro compounds,it has the widespread application prospects.In this paper,N-methylhydroxylamine hydrochloride was synthesized by electrochemical method and the electrochemcial properties of nitromethane on Ti/Ti02 film electrode was studied.Ti/TiO2 film electrode was prepared by anodic oxidation at constant voltage.(electrolyte:1mol/L sulfuric acid solution,Electrode:polished Ti anode and Pt cathode electrode,oxidation temperature:20 ?,oxidation voltage:20V,oxidation time:1.5h).The prepared electrode was charaterized by X-ray diffraction(XRD),scanning electron microscope(SEM)and X-ray photoelectron spectroscopy(XPS)for phase structure,surface topography,surface elements and distribution of the valence state of the Ti/TiO2 film electrode.The analysis results showed that the electorode prepared has the rough surface with irregular particles,the surface of the electrode containing only two elements of Ti and O,and Ti(IV)in the form of positive and no other valence states,these indicates the formation of TiO2 film on the surface of the electrode.TiO2 film increases the surface area of the electrodes so that it is helpful to improve the electrochemical properties.The electrocatalytic properties of Ti/TiO2 film electrode towards the electrocatalytic reduction of nitromethane to N-MHA were evaluated by CV,LSV,in situ FTIR and preparative electrolysis experiments.Experimental evidence was presented that Ti/Ti02 film electrode had good heterogeneous electrocatalytic activity for the reduction of nitromethane and the reduction process was a rapid and irreversible reaction.The mechanism of electrocatalytic reduction of nitromethane to N-MHA was obtained.The prepared Ti/Ti02 film electrode was used as cathode to electrosynthesis N-MHA.The results are as follows:The undivided cell was not suitable for the electrosynthesis experiment,so the divided cell with Ti/Ti02 film electrode as the cathode,DSA as the anode was adopted,under the conditions of temperature 30 ?,current density 4000 A/m2 and 80%of the theory time,the yield and the current efficiency of N-MHA were highest,up to 60.02%and 74.99%.Compared with the bright Ti as the cathode,the yield of N-MHA increased at least 10%.Recycling of the electrolyte(1?5 cycles)was an effective way to improve the product yield and current efficiency up to 67.8%and 84.86%,respectively.7.8%and 9.87%higher than that of the original process.