Synthesis of Benzaldehyde and Succinic Acid by Paired Electrosynthesis with On-line Ultrasound

Abstract

In the electrolytic process of out-cell indirect electrosynthesis of benzaldehyde,electrolytic yield of electrooxidating Ce3+ to Ce4+ in an undivided electrolytic cell was lower,while in diaphragm electrolytic cell would cause a high energy consumption.Based on this,a research with a combination of indirect electrosynthesis benzaldehyde and direct electroreduction maleic acid to succinic acid was carried out,and a new paired electrosynthesis system was constructed,that was,ion membrane paired electrolysis for preparations of Ce4+ on PbO2/Pb anode coupling with succinic acid on Pb cathode using sulfuric acid solution as medium under ultrasonic radiation,then oxidizing toluene to benzaldehyde with the Ce4+ solution prepared in the first step.Experimental results showed that the synthesis of benzaldehyde and succinic acid by paired electrosynthesis with on-line ultrasound was feasible,and a high current efficiency could be obtained in both cathode and anode,which was 92.71% and 87.81% in average,respectively.Thus the total current efficiency was up to 180.52%.The percent conversion of maleic acid reached 92.09%,and the bath potential decreased 0.25 V.Besides,a good result was also obtained in oxidating toluene to benzaldehyde using the Ce4+ solution with on-line ultrasound,the yield of benzaldehyde was 95.78% in average.