The electrochemical hydrogenolysis of glucose
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Abstract
Previous investigators have studied the hydrogenolysis of sugars under high pressures and temperatures. The purpose of this investigation was to study the possibilities of producing low molecular weight polyhydric alcohols from glucose by electrochemical methods.
A procedure was devised for the separation of low molecular weight polyhydric alcohols from a mixture of polyhydric alcohols which constituted extracting the mixture with acetone at a temperature of 130 ℉. The acetone proved to be a solvent for the low molecular weight polyhydric alcohols.
Acetone-soluble material was produced by the electrolysis of glucose at lead or zinc cathodes in the presence of 10 per cent sodium hydroxide at a temperature of 100-110 ℉, and a current density of 7.0 amperes per square decimeter.
The range of current density investigated was from 4.0 to 7.0 amperes per square decimeter. The temperature was 100-110 ℉; the cathode material was lead sheet which was given a Tafel activation; the electrolyte contained 10 per cent sodium hydroxide and 7.5 per cent sodium sulfate; and the catholyte was agitated. The effect of the current density on the reduction of glucose and the production of acetone-soluble material was negligible over this range and condition of electrolysis.
The amount of acetone-soluble material produced at a current density of 7.0 amperes per square decimeter in the presence of ten per cent sodium hydroxide at a temperature of 100-110 ℉ was 80.8 per cent by weight of the glucose reduced. The amount of current passed was 14 ampere-hours. The acetone-soluble material produced in the presence of five per cent sodium hydroxide was 70.8 per cent for the same conditions and time of electrolysis. With variation of the amount of current passed to 28 and 42 ampere-hours, the acetone-soluble material produced in ten per cent sodium hydroxide was reduced to 56.9 and 15.1 per cent. The acetone-soluble material produced in the presence of five per cent sodium hydroxide was 26.4 and 11.3 per cent.
The electrolysis of sorbitol in the presence of ten per cent sodium hydroxide at a lead cathode at 100-110 ℉ with the passage of 14 ampere hours of current produced no acetone-soluble material.
The fractionation of the acetone-soluble material resulted in a fraction which distilled at 109-110 ℃ at 8 mm of pressure. The residue polymerized which set up to a hard water soluble, acetone-insoluble mass upon cooling.
A summary of the known properties of the distillable compound, as indicated by tests performed in this investigation, is as follows: A polyhydric, methyl ketone, or aldehyde. Soluble in water, acetone, and ethanol. Insoluble in ether. Boils at 109-110 ℃ at 8 mm pressure. Forms a 2-4 dinitrophenylhydrazone derivative with an uncorrected melting point of 225-227 ℃. The compound could not be identified from the literature.