Halate anions

Bromocresol purple (5.2...6.8) glutamic and ketoglutaric acids [217], halide and halate anions [91,218, 219] preservatives [220, 221] products of pyrolysis of epoxy resins [222] 5-aminodibenzocyclo-heptane derivatives [223] phenylalkanolamines, eph-edrine [224]... 

Habituating drugs 76 Halate anions 45 Halide anions 45 Halogen anions 231, 232 Halogen acids 189... 

Introducing a halogen into a hot basic solution causes a disproportionation process. Part of the halogen is reduced to the halide anion and another part of it is oxidized to the halate anion (equation 117). 

Reaction (11.4) is really a disproportionation reaction of the halate(I) anion 3XO 2X -E XO. ) Reaction (11.3) is favoured by the use of dilute alkali and low temperature, since the halate(I) anions, XO are thermally unstable and readily disproportionate (i.e. reaction (11.4)). The stability of the halate(I) anion, XO , decreases from chlorine to iodine and the iodate(I) ion disproportionates very rapidly even at room temperature. 

The trivalent [P04] and [As04] ions react similarly. Examples of anions that give insoluble Hg(I) compounds in this way include halides, pseudohalides, halates, carboxylates and sulfate. A trace of HNO3 or HCIO4 is often added to the solution of the Hg(I) nitrate or perchlorate to prevent disproportionation induced by alkali. Table 1 lists common Hg(I) derivatives prepared in this way and includes values of the solubility products of the sparingly soluble Hg(I) compounds where these are measured. A similar reaction is used to prepare HgjCO, from a soluble bicarbonate ... 

The chlorate, bromate, and iodate ions are stable in solution, and many salts derived from these anions are familiar compounds. Although, as we have seen, the halate ions result from basic hydrolysis of the elemental halogens in warm solution, such a hydrolysis is generally not the method of choice for preparation of pure halates, since five sixths of the halogen... 

Chlorate is the most important halate and is produced, on an industrial scale, by electrolysis of a halide solution in a diaphragmless cell, which promotes efficient mixing. This arrangement allows the chlorine produced at the anode to react with the hydroxyl anion at the cathode, forming the hypochlorous anion, which is then further oxidized to chlorate, whether by oxidation at the anode or through... 

The oxidation of a halide anion with its own halate is sometimes qnantitative and is used in the quantitative analysis of bromide and iodide (equation 119). 

The thermodynamic data for complexation of trivalent lanthanide and actinide cations with halate and haloacetate anions are reported. These data are analyzed for estimates of the relative amounts of inner (contact) and outer (solvent separated) sphere complexation. The halate data reflected increasing inner sphere character as the halic acid pKa increased. Use of a Born-type equation with the haloacetic acid pKa values allowed estimation of the effective charge of the carboxylate group. These values were, in turn, used to calculate the inner sphere stability constants with the M(III) ions. This analysis indicates increasing the inner sphere complexation with increasing pKa but relatively constant outer sphere complexation. 

Trivalent lanthanide and actinide cations form labile, ionic complexes of both inner and outer sphere character. Consequently, they are useful probes to study inner-outer sphere complexation competition due to ligand properties. Two earlier papers have reported complexation of these cations by two series of related anions, the halates (9) and the chloroacetates (10). In this paper we offer a more extensive analysis of the inner-outer sphere competition in these complexes. 

With hot alkaU, however, the same reactants give different products. The hypohalite anions, the initial products of the reaction, disproportionate on warming to halate (XO ) and halide (X , X = Cl, Br, I) ... 

For hypochlorous acid, 172) the minimum stability exists at pH 6.7 and the maximum stability at pH 13. Various anions exert a catalytic effect. For hypobromite solutions, these positions of maximum and minimum stability are shifted to more alkaline conditions. The velocity of halate formation increases greatly in the order CIO3 < BrOs < IO3. 

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