Direct Electrooxidation Synthesis Of Anisaldehyde Dimethyl Acetal In A Quasi Capillary Gap Cell

Anisaldehyde dimethyl acetal?p-MBDMA?is an important fine chemical,due to widely used as a precursor and fragrance addition,including pharmaceuticals,dye-stuffs,plating additives,pesticides and flavor ingredients.Because of the complex process,long reaction time and serious pollution for the traditional chemical synthesis of p-MBDMA,many foreign and domestic researchers are gradually focusing on the electrochemical synthesis method,which is environmental friendly and clean productional.Electrochemistry can provide valuable cost efficient and environmental friendly contributions to industrial process development with a minimum of waste production and toxic material.The electrochemical reactions serve as powerful methods for the synthesis of organic compounds because highly reactive species can be easily generated under mild conditions.At present,the industrial electrooxidation synthesis ofp-MBDMA is achieved by BASF company with a production rate of 3,500 tons per year.While the foreign core technology is secret,few studies on direct electrooxidation of p-methoxytoluene have been reported and the aspect of this field remains blank.The electrochemical behaviors of p-methoxytoluene and p-methoxybenzaldehyde dimethyl acetal in methanol solution were studied by cyclic voltammetry and linear sweep voltammetry.The influences of the concentration of p-MT and the scanning rate on electrochemical test were investigated.The influence of operation condition,such as anodic electrode materials,supporting electrolyte and current density on direct electrochemical oxidation synthesis of p-MBDMA in a quasi capillary gap cell were investigated by galvanostatic method.The determination of p-MBDMA in the process of electrolysis was established by high performance liquid chromatography.And the electrolytic performance was evaluated by the conversion,yield and current efficiency of the reaction.The experimental results showed the best chromatogram condition was as follows:acetonitrile-methanol-water?2:3:5?as mobile phase with pH 3?4 adjusted by phosphoric acid,flow rate 1.0 mL·min-1,column temperature 30?,methanol as dilute solution,injection volume 20 ?L.The production was detected at wavelength of 283 nm.Under the optimum operation condition of 0,8?1.0 mol·L-1 p-MT 1.0%?mass?sodium 2,4,6-trimethylbenzenesulphonate as supporting electrolyte,the yield and current efficiency could reach 75%and 47%at 1.5?1.6 Q*.During the process of electrolysis,the current density was changed from 3.0 to 2.0 A·dm^-2 at 0.8 Q*and the operation condition was under the electrolyte solution flow rate of 20 L·h^-1 at temperature 40?.The research provided an important basis for industrialization of electrochemical oxidation synthesis of p-MBDMA.