Halogens periodic acid oxidations

Green, John W., The Halogen Oxidation of Simple Carbohydrates, Excluding the Action of Periodic Acid, III, 129-184... 

Bromic acid, 0248 Chloric acid, 3996 Hypochlorous acid, 3995 Iodic acid, 4424 Orthoperiodic acid, 4542 Perchloric acid, 3998 Periodic acid, 4425 See also HALOGEN OXIDES... 

Lhe elemental halogens as well as NCS and NBS, N-ehloroben-zotriazole. chloramine-T. MCPBA, periodic acid, and such hea-vy-mctal oxidants as thallium(IIl) nitrate or CAN... 

THE HALOGEN OXIDATION OF SIMPLE CARBOHYDRATES, EXCLUDING THE ACTION OF PERIODIC ACID... 

Gottfried, J. B. See Dean, G. R. Gottschalk, Alfred, Principles Underlying Enzyme Specificity in the Domain of Carbohydrates, V, 49-78 Green, John W., The Halogen Oxidation of Simple Carbohydrates, Excluding the Action of Periodic Acid, III, 129-184... 

Complex side-reactions, including overoxidation, are likely to occur in the oxidations, and information on the mechanism of periodate oxidation and the periodate-oxidation products of starch, cellulose, xylan, and other polysaccharides have been discussed. Thus, the limit of periodate oxidation is not always that expected, and the formation of interresidue hemiacetal structures during the oxidation can cause an early halt. - It is not until these structures have been reduced that oxidation can proceed once more. Other oxidants, such as dichromate-sulfuric acid, dichromate-oxalic acid, and sodium hypochlorite (which cause more extensive reactions), have been investigated with respect to cellulose and periodate-oxidized cellulose. Further oxidation of 2,3-dialdehydocel-lulose with halogen peroxy acids gives 2,3-dicarboxycellulose. ... 

Some catalyzed reactions involve an induction period, defined as the interval between addition of the last reactant (i.e., the start of the catalyzed reaction) and the appearance of a reaction product, during which the reaction appears not to develop. This phenomenon was first observed by Landolt in the reaction between iodate and sulfite ions in an acid medium, which releases iodine after an induction period. This is known as the Landolt effect and is chiefly exhibited by redox reactions involving halogens in various oxidation states. Thus, a slow reaction [VO] is coupled to a fast one [VIll] via the reaction product of the former ... 

Co2(CO)g] and [Co4(CO)i2] are air-sensitive however, large crystals of these compounds do not undergo noticeable oxidation in a short period of time. Solutions of these carbonyls rapidly undergo decomposition. The halogens quantitatively oxidize [Co2(CO)g] and [ 04(00)12] to Co(II) salts. Oxidizing acids oxidize [Co2(CO)g] to Co(II) compounds and nonoxidizing acids react with this carbonyl only slowly and partially. 

The halogens and their oxyacids probably are the most important oxidants used in the carbohydrate field. They are widely used as bleaching agents, but the mechanism of this action remains to be clarified. As reagents for preparatory purposes (particularly for aldonic acids and lactones) and for analytical procedures, they are very important. Periodic acid, discussed in a later section, has an important application for the elucidation of structures of carbohydrates. A number of valuable commercial products are made by treatment of polysaccharides with halogens, particularly chlorine or hypochlorous acid, but the nature of these actions, such as the modification of starch, has not been clarified. 

The determination of halogens at oxidation states -l-ni, - -V, -i-VII may be achieved by indirect iodometry. We just mentioned that for the chlorate ions case in which chlorine is at oxidation state -l-V. We have also already seen that iodate ions quantitatively oxidize iodide ions in acidic medium. That was for the standardization of thiosulfate solutions. Likewise, periodate ions and periodic acids quantitatively oxidize iodide ions into iodine (see the next chapter). 

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