Iodate oxidant

Hanna, A., Saul, A., and Showalter, K. (1982). Detailed studies of propagating fronts in the iodate oxidation of arsenous acid. J. Am. Chem. Soc., 104, 3838-44. 

In an acidic solution, iodate oxidizes trivalent antimony to the pentavalent state. This reaction may be used to estimate the antimony in solution. A typical procedure consists of the following steps ... 

It will be appreciated that iodate is incompatible with both iodide (cf. Section IV.21, reaction 6) and with thiocyanate (Section IV.21, reaction 9) since iodine is liberated in acid solution. Also sulphide is incompatible with both bromate and iodate (oxidation to sulphate occurs), and an arsenite is oxidized by iodate in acid solution. These facts should therefore be borne in mind when interpreting Table V.30. An independent test for iodate (test 11) is provided below this can be performed before the silver nitrate tests. 

Gribshaw et al. (1981) studied the chemical waves in the acidic iodate oxidation of... 

Iodate oxidizes iodide to Ij (which is volatile), thus increasing the instability of iodide. This interaction has important practical consequences when iodized with a mixture of potassium iodate and iodide, bread loses 34% of its iodine over one week of storage, while with either iodide or iodate alone its iodine content remains stable (Anke et al., 1998). 

Biichi and Kamikawa reinvestigated the earlier work of Bu Lock and Harley-Mason and showed that potassium iodate oxidation of racemic dopa esters 93 (R = Me, Et) followed by dithionite reduction and acetylation gives the 5,6-diacetoxy-7-iodo esters 95 (R = Me, Et) (Scheme 21) (77JOC4153) (51JCS2248). Catalytic reduction removes the 7-iodo substituent and the esters 96 can then be hydrolysed to cyclodopa using known methods (Scheme 20). The 2,3-dihydroindoles 96 were fully characterized by conversion to the salts 97. The intermediate aminochrome 94 (R = Me) was isolated and characterized. See Section IVB for further details on the mechanism of iodination during this oxidation. 

The iodate oxidation of arsenous acid is conveniently described in terms of two component processes (De Kepper et al., 1981a Hanna et al., 1982) process A, the Dushman reaction (Dushman, 1904), and process B, the Roebuck reaction (Roebuck, 1902). 

When arsenous acid is in stoichiometric excess ([As(III)]o > 3[IOJ]o), the stoichiometry of the iodate oxidation of arsenous acid is given by... 

In acid solution, iodates oxidize pyrogallol to purpurogallin. Strong oxidizing agents, such as iodine and chromate, act in the same way. Persulfate, nitrate, and bromate give similar colors, which can be distinguished if parallel tests are made. 

Potassium iodate oxidizes iodide ions for pH values weaker than about 7 (see Fig. 18.1 in Chap. 18). The liberated iodine is detected by its partitioning into carbon... 

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