| Methods for the synthesis of aromatic fluorine compound has been attracted much attention by the industry and scientific community domestic and abroad.Electrochemical fluorination method with the advantages of mild reaction conditions,low toxicity,less pollution etc.,are gradually occupying an important position in the synthesis methods of organic fluoride.Based on the review of research and development about organic electrochemical fluorination,the electrochemical oxidation performance of aromatic compounds(take toluene for example)were investigated by different characterization methods and electrochemical techniques,such as gas chromatography-mass spectrum(GC-MS),gas chromatography(GC),cyclic voltammetry and electrochemical impedance spectroscopy.In this dissertation,the electrochemical oxidation performance of toluene,in the solution with TBAP as supporting electrolyte,was systematically investigated.Furthermore,the effects of the concentration of reactant,scan rates and reaction temperature and ultrasound-assisted reaction were studied using Et3N·3HF as fluorination agent and supporting electrolyte.On the other hand,the aromatic iodides were selected as the medium.The influencing factors of the electrochemical oxidation of aromatic iodide,such as solvent,concentration,supporting electrolyte,the type of the aromatic iodide etc.,were explored.The results are shown as fellows:(1)Toluene can be electro-oxided on the anode in TBAP-CH3CN and Et3N-3HF-CH3CN solutions.The optimal reaction conditions for electro-oxidation of toluene in Et3N·3HF-CH3CN system are as fellows:the concentration of toluene is 0.5mol·L-1;the concentration of Et3N·3HF is 1mol·L-1;the reaction temperature is 40℃.It is obtained from cyclic voltammetry that the anodic fluorination of toluene is controlled by diffusion step.The results of constant potential electrolys show that the electrochemical fluorination of toluene is blocked by the nonconducting polymer film formed rapidly at the Pt anode,as the electrochemical fluorinaton reacting in the solution of CH3CN.With ultrasound assisted,the electrode surface can be cleaned,and the rate of mass transfer in the solution is enhanced.So the surface of the electrode can be prevented from the nonconducting polymer film,increasing the the time space yield.(2)Based on the study of electrolyte systems of iodobenzene and p-iodoanisole,the electrochemical oxidation performance of them can be learned.Experimental results show that acetonitrile is a suitable solvent for the reaction system of electrochemical fluorination.The electrochemical oxidation of iodobenzene in platinum electrode is mainly controlled by diffusion.Electrochemical oxidation of p-iodoanisole in Et3N-3HF-CH3CN is easier to occur.In other words,it’s more suitable than the iodobenzene to be the medium of electrochemical fluorination reaction. |
