Glucose electroreduction

D-Mannitol is much less soluble in ethanol/water than sorbitol (glucitol) because it is symmetrical and therefore crystallizes more easily. Separation by crystallization is simple. Electroreduction of D-glucose under alkaline conditions gives a mixture of 80% glucitol and 20% mannitol (10 g 0.80). 

Acyclic alditols.-Studies of the vitreous transition in maltitol glasses and the thermal behaviour of four conunercially available hexitols during crystallization and vitrefication have appeared. Reports on the water sorption and solubility of polyols, and on the kinetics of mercury-mediated electroreduction of glucose, galactose and lactose have also been published. 

Park K, Pintauro PN, Baizer MM, Nobe K (1985) Flow rate studies of the paired electro-oxidation and electroreduction of glucose. J Electrochem Soc 132 1850-1855... 

D-Mannitol has been synthesized by several methods. The commercial methods have been the electroreduction and more recently catalytic reduction of D-glucose, under more or less alkaline conditions sorbitol is formed simultaneously. Depending on the alkalinity, over 20 % of the glucose can be converted to D-mannitol in this manner. Catalytic hydrogenation of invert sugar to give a similar mixture of D-mannitol and sorbitol would appear to be a method capable of commercial exploitation. 

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