Reduction of iodate

The appearance of free iodine during the periodate oxidation of compounds having an active hydrogen atom (27) or an ene-diol structure (1,39) has frequently been observed, and this implies that further reduction of iodate, formed from periodate during the main reaction, takes place. It has, in fact, been shown that, in acid solution, iodate is fairly readily reduced by such compounds as triose reductone (27), dihydfoxy-fumaric (39), and tartronic (32) acids. 

Reduction of iodates by ene-diols. . 100 Reduction of unsaturated acetates. 153 Replacement of a sulfonate ester... 

The "iodine clock" reaction Rate of reduction of iodate by sulfite was increased... 

Iodine water is added to an acetic acid sodium acetate buffered sample to reoxidise to iodate any iodine-containing substances produced by reduction of iodate by naturally occurring reducing substances present in the sample. Total iodate (i.e., iodate present in the original sample as iodate plus additional iodate produced by iodine water treatment) is then reacted with phenol solution at... 

The iodine produced intially by the reduction of iodate [Eq. (h) undergoes solvolysis in a polar solvent as expressed in the following reaction ... 

Councell TB, Lada ER, Lovley DR. 1997. Microbial reduction of iodate. Water Air Soil Pollution 100 99-106. 

Bassam Z. Shakhashiri, "Color Variations of the Landolt Reaction," Chemical Demonstrations, A Handbook for Teachers of Chemistry, Vol. 4 (The University of Wisconsin Press, Madison, 1992), pp. 26-28. Three pairs of colorless solutions are mixed. After 10 seconds the three mixtures turn red, yellow, and blue, respectively. Each clock reaction is the reduction of iodate by bisulfite. The observed colors are related to the amount of triiodide produced, which depends on the relative amounts of iodate and bisulfite reacted, and whether or not starch is present. 

The solution must be maintained slightly alkaline by adding a buffer such as sodium bicarbonate or borax. This prevents any further reduction of iodate. 

Oxidation may be a problem only prior to closure of the waste form canister since the earth s crust is predominantly reducing. However, reduction of iodates becomes possible after water intrusion and oxidation of iodides can occur on reaching atmospheric environment. Allard et al. (11) predict that any released Iodine in the groundwater will be as iodide. 

Until recently no anhydrous iodites were known. In 1965 Harmelin and Duval3 reported a general method for the preparation of iodites the solid-state reduction of iodates by metallic lead. Since the reaction occurs without loss of weight, it was postulated to occur according to... 

As discussed in Section 3, the EC mechanism is a common electrode reaction route. An example of an EC reaction studied by RDE techniques is (87), the iodide mediated reduction of iodate anions in acidic aqueous media (Beran and Bruckenstein, 1968). Iodide is formed at the electrode surface through reduction of iodine in the aqueous solution. 

Farrenkopf, A. M., Dollhopf, M. E., Chadhain, S. N., Luther, G. W. I., and Nealson, K. H. (1997). Reduction of iodate in seawater during Arabian Sea shipboard incubations and in laboratory cultures of the marine bacterium Shewanella puterfaciens strain MR-4. Mar. Chem. 57, 347-354. 

In alkaline aqueous solution, reduction of iodate ion by tetrahydroborate ion has been found to compete with hydrolysis, the rate law being of the form... 

The preparation of iodine involves reduction of iodate ion from NaI03 with sodium hydrogen sulfite, NaHSOj. 

The reduction of iodate with aqueous sulfiir dioxide would be far cheaper than reduction with because sulfur dioxide costs less than tin. One reason this is so is because sulfuric acid, for which SOj is an mtermediate, is prepared worldwide on an enormous scale. 

IIIA) 1931-1 Liebhafsky, H. A. Reactions involving Hydrogen Peroxide, Iodine, and Iodate. III. The Reduction of Iodate ion by Hydrogen Peroxide, J. Amer. Chem. Soc. vol. 53, 896-911... 

In the presence of concentrated HCl (>4N), hydrazine can be titrated directly with standard iodate solution. The addition of iodate is continued until the iodine color is discharged. Actually, the initial reaction involves reduction of iodate to iodine chloride, resulting in the disappearance of the iodine eolor. A few milliliters of chloroform or carbon tetrachloride are added to dissolve the iodine, and the endpoint is reached when the solvent layer is decolorized. 

In a slightly basic solution (ca. pH 8) such as seawater, both iodate and iodide are present, but iodate is more stable than iodide under oxic conditions (Wong, 1991). However, direct oxidation of iodide to iodate is very slow due to the kinetic barrier, and thus iodide is stable for a long time in seawater once it is formed by biological and/ or abiological process. On the other hand, as iodate is thermodynamically stable, the reduction of iodate to iodide does not occur spontaneously. 

In addition, hypoiodous acid HOI can be formed by radiolytic oxidation of iodide in aqueous solution saturated with nitrous oxide or by radiolytic reduction of iodate in hydrogen-saturated aqueous solution (Fletcher and Miller, 1985). 

Bromate and iodate salts are prepared on a much smaller scale than chlorates. Under appropriate conditions, these ions undergo oscillating chemical reactions known as chemical clocks. The best known clock reaction is observed when an acidified solution of sodium sulfite (Na2S03) is mixed with an excess of iodate in the presence of starch indicator. After a suitable induction period allowing for sodium sulfite reduction of iodate to iodide [Eq. (44)], the blue, starch-iodine color periodically appears and disappears as the iodide is oxidized to iodine [Eq. (45)], and the iodine is reduced back to iodide [Eq. (46)]. 

Reductions of iodate and bromate by and have also been reported in a... 

Reduction of iodate to iodide before total iodine analysis was necessary because the species had different sensitivities by ICP-MS. Gradient elution with 5 mM KNO3... 

A simple and quick method in FIA using a glassy carbon disk electrode modified with a molybdenum oxide film has been proposed for the quantification of iodate in commercial salt samples [48]. In this study, the film actuated as a catalytic agent in the reduction of iodate and a linear response was observed (from 1.0 x 10 to 1.0 x 10 mol r ). Other amperometric method coupled to FIA exploring the electrochemical reduction of iodate was also described [49]. Here, the authors used a more favorable working potential (+0.2 V vs. Ag/AgCl) in the presence of a solution of 1.0% w/v NaCl, 0.02% w/v KI, and 0.1 mol 1 HCl as carrier. 

Gupta YK, Bhargave AP (1965) The oxidation of iodide to iodite and the reduction of iodate to iodite in iodine solutions of permanganate and some of the carboxylic acids. Bull Chem Soc Jpn 38 12-16... 

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