60] - Selective Catalytic Oxidations of Carbohydrates

Abstract

This chapter discusses selective catalytic oxidations of carbohydrates. The catalytic oxidation of primary and secondary hydroxyl groups with oxygen brought into contact with platinum is highly selective. Reaction conditions are comparatively mild and, as a rule, isolation of the reaction products is simple. Unlike many other oxidation methods, this selective method does not require the blocking of hydroxyl groups. Of the hydroxyl groups, the primary ones are attacked preferentially and are oxidized in neutral or slightly acidic solution to the aldehyde and in alkaline solution to a carboxylic acid. Thereby, it is possible to convert glycitols to mixtures of aldoses, aldonic acids, and aldaric acids with one component predominating. Axial hydroxyl groups are oxidized in preference to equatorial hydroxyl groups. If several axial groups are present in a molecule, only one is oxidized.