Oxidation by periodic acid

Cyclic diols give dicarbonyl compounds The reactions are faster when the hydroxyl groups are cis than when they are trans but both stereoisomers are oxidized by periodic acid... 

Several mechanisms34 have been proposed for this reaction. That of Weygand,36 in which an Amadori rearrangement is proposed, has considerable merit.37 Illustrations of unusual osazone formation are described by Bonner and Drisko.38 When phenyl /S-D-xylopyranosyl sulfone (XXII) or /J-D-glucopyranosyl sulfone (XXIV) is oxidized by periodic acid, a dialdehyde oxidation product (XXIII or XXV), which is susceptible toward further oxidation, is obtained. The reaction of XXIII or XXV with phenylhydrazine yields glyoxal phenylosazone and benzenesulfinic acid. Surprisingly, both XXII and XXIII react with phenylhydrazine to form D-xylosazone and D-glucosazone, respectively. 

Ethylene oxide in air may be measured directly in situ by a rapid colorimetric technique (Pritts et al., 1982). Air is drawn through a multipart detector tube consisting of three reactor tubes containing periodic acid, xylene, and cone. E12S04, respectively. Ethylene oxide is oxidized by periodic acid to formaldehyde... 

An aqueous solution of sulfuric acid and a salt of periodic add, trisodium paraperiodate, or one of the potassium periodates, has been used frequently as a substitute for pure periodic add. When the product of the oxidation reaction is to be isolated, the effect of the presence of metal ions on the yield should be considered. If the product is volatile or slightly soluble, or is isolated either as a slightly soluble derivative or by extraction with organic solvents, the presence of metal ions should not reduce the yield. In the Case of certain methylhexosides34 which were oxidized by periodic acid formed from potassium metaperiodate and an equivalent of sulfuric add in aqueous solution, the presence of potassium ions was found to cause a low yield of the crystalline strontium salt prepared by the strontium hypobromite oxidation of the dialdehyde resulting from the periodic add reaction. Oxidation by pure periodic add, a solution of which is prepared either from crystalline paraperiodic add or by the previously mentioned method from potassium metaperiodate, is desirable when the presence of difficultly removed metal ions affects the yield adversely. 

Most of the compounds that had been reported (before March, 1942) to show cleavage oxidation by periodic acid are recorded in the table the substances are listed alphabetically in the following groups of related compounds (1) carbocyclic compounds (2) carbohydrates (3) a-diketones and a-ketols (4) hydroxyamino compounds (5) polyhydroxy and hydroxyketo acids (6) polyhydroxy alcohols (7) steroids (8) miscellaneous compounds. French journals after May, 1940, and the majority of other foreign publications after June, 1941, were unavailable for the survey. 

When the methylenation of D-mannitol is carried out at a higher temperature and for a shorter time, there is produced a dimethylene-D-mannitol (m. p. 204-208°), in addition to the triacetal previously mentioned.68 The dimethylene compound is not oxidized by periodic acid and its ditosyl ester does not exchange with sodium iodide, even in acetic anhydride at 140°.62 Consequently it must be either 1,2,4,6- or 1,3,4,6-dimethylene-D-mannitol (the 1,2,4,6- and 1,3,5,6-structures are identical) the 1,3 4,6-structure was favored by Ness, Hann and Hudson40 in view of the rapidity of its conversion into 1,3 2,5 4,6-trimethylene-D-mannitol. 

Periodic acid is a versatile oxidant since, depending on pH, the redox potential for the periodate-iodate couple varies from 0.7 V in aqueous basic media to 1.6 V in aqueous acidic media.Based on this observation, Villemin and Ricard devised an oxidative cleavage of glycols, in which mcjo-l,2-diphenyl-1,2-ethanediol was oxidized by periodic acid on alumina to benzaldehyde in 82% yield in aqueous ethanol (90% ethanol) at room temperature in 26 h. The same supported oxidant converted aromatics into quinones. In the presence of transition metal complexes (Mn ), a-arylalkenes suffer oxidative cleavage to aldehydes. For example, tran.r-stilbene gives benzaldehyde at room temperature. 

The use of oxidation by periodic acid, sodium periodate, or lead tetraacetate in structural studies on carbohydrates is well known. These reagents act on a-glycols with the production of carbonyl groups and the consumption of one molecule of oxidant for each such glycol group. Where there is a primary amino group in the position a to a hydroxyl, similar oxidation... 

Action of Oxidizing Agents. Oxidizing agents attack pectin differently. En-diols in the presence of hydrogen peroxide are especially active (5). The oxidation by periodic acid is the smaller, the higher the acetyl content of the pectic substance (25). Sodium chlorite and chlorine dioxide, however, do not affect pectins (2S). 

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