Halates and Perhalates

Other oxoacid salts of the alkali metals are discussed in later chapters, e.g. borates (p. 205), silicates (p. 347), phosphites and phosphates (p. 510), sulfites, hydrogensulfates, thiosulfates, etc. (p. 706) selenites, selenates, tellurites and tellurates (p. 781), hypohalites, halites, halates and perhalates (p. 853), etc. 

Molecular halogen, halide, halate, and perhalate ions. The exchange rate between hahde ions and molecular halogens, namely Cl and CI2, Br and Br2 and also I and I2, in aqueous solutions is too large to be measured by an ordinary radiochemical method. 

The various reactions of bromates and iodates are summarized in the. schemes on p. 866. The oxidation of halates to perhalates is considered further in the next section. 

The exchange between molecular halogen or hahdes and halates or perhalates is slow. The iodine-iodate-exchange reaction was investigated in detail by Myers and Kennedy (1950). The reaction is complex and a possible mechanism was proposed, which involves two-electron transfer from a chemical species containing I to one containing 102 as a rate determining step. 

Finally, we must consider the possibility of production of perhalate ions by disproportionation of the halate ions. Since the acids H0X02 and HOXO3 are all strong, these equilibria are independent of pH. The reaction... 

Brown, D. Halides, Halates, Perhalates, Thiocyanates, Selenocyanates, Cyanates, and Cyanides. In Comprehensive Inorganic Chemistry Bailar, J. C., Emeleus, H. J., Nyholm, R. N., Trotman-Dickenson, A. F., Eds. Pergamon ... 

Halates are readily prepared by the base hydrolysis of the halogen. Bromates and iodates can also be synthesized by the oxidation of the halide. Only iodic acid can be isolated outside of aqueous solution. Chlorates are excellent oxidizing agents, lodate occurs naturally, is a source of elemental iodine, and is a primary standard for iodimetry. The perhalic acids of chlorine and iodine are much easier to prepare than that of bromine. Perchloric acid, like sulfuric and phosphoric acid in previous groups, has a tetrahedral structure around the central atom and involves dir-pir... 

---