Synthesis Of Sorbitol Mannitol And Gluconic Acid By Electrolysis Of Glucose In Pairs

Organic electrosynthesis is a kind of green technology according with "atomic economy". Sorbitol mannitol and gluconic acid that are widely used can be obtained with this method from glucose. In this letter, glucose was paired electrolyzed to sorbitol mannitol and gluconic acid using Raney Ni as cathode. A new kind of electrode with Raney Ni surface was prepared from Ni-Al alloy by activating in hot sodium hydroxide solution. Using this electrode as cathode, electrolyzing glucose with constant current in plane electrode cell, the optimum experiment condition was as follows: current density 2.0A/dm~2, temperature 35℃, PH=11,1.2 times of theoretical coulombs, in the electrolyte containing 0.6mol/L glucose and 0.5mol/L sodium sulfate. Under this condition, the current efficiency and the glucose reduction ratio were 60% and 71.7%, much higher than that on Pb cathode while there was 19.7% mannitol in the product. Then, the glucose reduction ratio the current efficiency, and mannitol ratio in the product were improved to 82.2%, 68.5% and 28.7% by ameliorating technics. At last, the paired electrolysis of glucose was studied with indirect oxidation of glucose as anodic reaction, obtaining 81.1% reduction ratio and 67.6% current efficiency on cathode, 82.7% and 68.9% on anode. The total glucose conversation ratio and current efficiency were 163.8% and 136.5%, which increased high compared with single electrode reaction.In course of using, Raney Ni cathode were poisoned by mannitol and sorbitol adsorbing on the electrode, which could be activated again in hot sodium hydroxide solution. Besides, the on-line monitoring of paired electrolysis of glucose was studied using Spectrophotometry method for the first time, which could exactly, fast determine the reducing sugar and gluconic acid in the electrolytes. It was of great significance for the development of paired electrolysis of glucose.