Periodic acid, reaction with 1,2-diols

Diols are oxidized to ketones and/or aldehydes by periodic acid (HIO4). Periodic acid reacts with the diol to form a cyclic intermediate. The reaction takes place because iodine is in a highly positive oxidation state (+7), so it readily accepts electrons. When the intermediate breaks down, the bond between the two carbons bonded to the OH groups breaks. If the carbon that is bonded to an OH group is also bonded to two... 

A reaction characteristic of vicinal diols is their oxidative cleavage on treatment with periodic acid (HIO4) The carbon-carbon bond of the vicinal diol unit is broken and two carbonyl groups result Periodic acid is reduced to iodic acid (HIO3)... 

Periodic acid oxidation (Section 15 12) finds extensive use as an analytical method m carbohydrate chemistry Structural information is obtained by measuring the number of equivalents of periodic acid that react with a given compound and by identifying the reaction products A vicinal diol consumes one equivalent of penodate and is cleaved to two carbonyl compounds... 

The oxidative cleavage of the central carbon-carbon bond in a vicinal diol 1, by reaction with lead tetraacetate or periodic acid, yields two carbonyl compounds 2 and 3 as products. 

The cleavage of 1,2-diols 1 by periodic acid is associated with the name of the French chemist Malaprade. The reaction mechanism is related to that outlined above, and is likely to involve a five-membered ring periodate ester intermediate 7 ... 

Aqueous periodic acid can be used to achieve glycol cleavage, combined with anodic oxidation of the iodate, which is formed, back to periodate [70]. Oxidation of iodate is catalysed at a lead dioxide anode [71] but at the potentials required, aldehydes are oxidised to the corresponding acids. Due to this further reaction, the redox-mediated cleavage of diols to form an aldehyde may be difficult to achieve witli a catalytic amount of periodic acid. Cleavage using a stoichiometric amount of periodic acid, followed by recovery of the iodic acid and then its electochemical oxidation, has been achieved [72]. 

The Malaprade Periodic Acid Oxidation Reaction oxidizes 1,2 diols or 2-amino alcohols with periodic acid ... 

Among examples of applications of polarography to the study of homogeneous kinetics, the oxidation of 1,2-diols with periodic acid (21) can be mentioned. In this reaction the decrease in the concentration can be followed (Fig. 10). Furthermore, it can be confirmed, whether all the... 

This reaction pathway is suitable for cis as well as tram diols. In principle, the oxidative cleavage is achieved by lead tetraacetate as well. However, these reagents are complementary, since periodic acid compounds are best used in water and lead tetraacetate in organic solvents. The last step is the reduction of the aldehyde with three equivalents of sodium borohydride to provide alcohol 5. 

Mechanism of staining Periodic acid opens the sugar rings at cis-diol bonds (i.e., the C-2—C-3 bond of glucose) to form two aldehyde groups and iodate (IOJ). Then the =+NH2 group of the dye reacts to form a so-called Schiff base bond with the aldehyde, thus linking the dye to the carbohydrate. The basic reaction is ... 

In addition to the oxidative scission of 1,2-diols, the reaction can be extended to related 1,2-bifunc-tional compounds such as oxiranes, 1,2-dicarbonyl compounds, 2-hydroxy aldehydes, ketones and acids, a-amino alcohols, 1,2-diamines and also to polyols. LTA cleaves a-hydroxy acids much more readily than do periodates and both reagents oxidize 2-hydroxy aldehydes and 1,2-dicarbonyl compounds relatively slowly. Only periodic acid in water reacts with oxiranes via the corresponding diols. 

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