GB365414A - Process for the electrolytic oxidation of aldoses - Google Patents

Abstract

365,414. Electrolytic oxidation of aldoses. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Rohm & Haas Co. ; 222, West Washington Square, Philadelphia, U.S.A.) March 27, 1931, No. 9412. [Class 41.] Aldoses are oxidized by electrolysis with an insoluble anode in the presence of a suitable base such as calcium hydroxide, calcium carbonate, magnesium hydroxide or sodium carbonate and of a bromide or iodide to form a salt of the corresponding monocarboxylic acid. The anode may be of copper, lead, iron or nickel. No diaphragm is necessary. The electrolyte should be agitated to keep the base in suspension. The halogen salt is not consumed and may be used again. In an example 40 parts of glucose, 4 parts of potassium iodide and 9 parts of calcium hydroxide are mixed in 200 parts of water and electrolyzed in a copper cup serving as cathode with a rotating graphite anode at a temperature of 10-15‹ C. and current density 25 amps. per sq. ft. When the theoretical amount of current has passed, the solution is filtered and evaporated. Calcium gluconate crystallizes out. In another example sodium carbonate is employed as the base and sodium gluconate is precipitated from the electrolyzed solution by addition of alcohol. In other examples lactose is treated for production of calcium lactobionate and galactose for the production of calcium galactonate. Mixtures of aldoses and ketoses may be separated by the process, the ketoses not being oxidized. In an example, a solution containing 54 gms. of invert sugar to which is added 2 gms. of potassium iodide and 5.5 gms. of lime is. electrolyzed. After electrolysis excess lime is neutralized with sulphuric acid and the solution partially evaporated. A precipitate of calcium gluconate is centrifuged off. The filtrate is concentrated and added slowly to 6 gms. of lime in 40 c.c. of water kept at 2‹ C. Calcium fructosate crystallizes out. A suspension of this is treated with carbon dioxide to remove calcium carbonate, and fructose is precipitated from the filtrate by alcohol.