Lead gluconic acid oxidation

When modifying the Pt catalyst by addition of bismuth or lead, a significant change in selectivity occurs. Oxidation of the primary terminal alcohol moiety in gluconic acid is no longer the dominating reaction. Instead oxidation of the a-hydroxy group, next to the carboxylic acid takes... 

A few polymerizations leading to nonhydrolyzable polysaccharides have been reported. The first was a base-catalyzed polymerization of 5,6-anhydro-l,2-0-isopropylidene-3-0-methyl-a-D-glucofuranose.u The polymerization was initiated most successfully with solid potassium or cesium hydroxide, and the d.p. achieved was —25. Hydrolysis gave a free, methylated, nonhydrolyzable polysaccharide, which was oxidized with hypoiodite to the poly(D-gluconic acid.)... 

Herzfeld reported a certain amount of oxidation on carbon atom six, as indicated by the formation of saccharic acid from D-glucose. The dicarboxylic acid was isolated from the normal oxidation mixture obtained in the preparation of D-gluconic acid from D-glucose or maltose. However, the reaction products were processed differently than usual following the procedure of Grieshammer, the acidic reaction mixture was neutralized with zinc carbonate instead of calcium or lead carbonate. Thus, the saccharic acid, which normally would be precipitated as an... 

The primary formation of o-gluconic acid and o-glucosone simultaneously with o-glucose and o-fructose may be accounted for by two types of oxidative scission of the disaccharide linkage, at a and b. The former leads to D-fructose and... 

While examining the effect of modified catalysts on aldaric acid formation it was found that Pt/C catalysts that were treated with lead salts were extremely selective for the oxidation of the hydroxy group next to the initially formed carboxylic acid to give 2-keto gluconic acid. 2.83 xhese catalysts also promote the selective oxidation of a number of other a-hydroxy acids. For example, lactic acid has been oxidized to pyruvic acid in greater than 95% yield (Eqn. 21.27).83 Similar results have been observed with lead doped Pd/C catalysts. 2,75... 

The main role of lead adatoms seems to be a decrease of the formation of byproducts, and the appearance of new centers for the adsorption of hydroxyl species, required for the oxidation of an alcohol group into a carboxylic group. Conversely, in the case of the oxidation of D-gluconic acid to 2-keto-D-gluconic add, the change in selectivity in presence of lead adatoms was attributed by... 

More drastic oxidation of aldoses with hypoiodite leads to keto acids and finally to cleavage of carbon-carbon bonds. Honig and Tempus 199) claimed to have oxidized glucose stepwise to gluconic acid, 2-ketogluconic acid, and n-arabonic acid. However, other workers claim that the main product is 5-ketogluconic acid 200),... 

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