Perbromate

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Perbromate

Space-filling model of the perbromate anion, BrO−
4
Identifiers
3D model (
JSmol
)
ChEBI
ChemSpider
  • InChI=1S/BrHO4/c2-1(3,4)5/h(H,2,3,4,5)/p-1
    Key: LLYCMZGLHLKPPU-UHFFFAOYSA-M
  • [O-]Br(=O)(=O)=O
Properties
BrO4−
Molar mass 143.901 g·mol−1
Related compounds
Related compounds
bromite
bromate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

In

conjugate base of perbromic acid, in which bromine has the oxidation state +7.[1] Unlike its chlorine (ClO−4) and iodine (IO−4) analogs, it is difficult to synthesize.[2] It has tetrahedral molecular geometry.[3]

The term perbromate also refers to a compound that contains the BrO−
4 anion or the –OBrO
3 functional group.

The perbromate ion is a strong oxidizing agent.[2] The reduction potential for the BrO−
4/Br− couple is +0.68 V at pH 14. This is comparable to selenite's reduction potential.

Synthesis

Attempted syntheses of perbromates were unsuccessful until 1968, when it was finally obtained by the

selenium-83 in a selenate salt:[4][5]

83
SeO2−
4 → 83
BrO−
4 + β−

Subsequently, it was successfully synthesized again by the electrolysis of LiBrO
3, although only in low yield.[5][6] Later, it was obtained by the oxidation of bromate with xenon difluoride.[3][7] Once perbromates are obtained, perbromic acid can be produced by protonating BrO−
4.[2]

One effective method of producing perbromate is by the oxidation of bromate with fluorine under alkaline conditions:[2][8]

BrO−
3 + F
2 + 2 OH−
 → BrO−
4 + 2 F−
 + H
2O

This synthesis is much easier to perform on a large scale than the electrolysis route or oxidation by xenon difluoride.[8]

In 2011 a new, more effective synthesis was discovered: perbromate ions were formed through the reaction of hypobromite and bromate ions in an alkaline sodium hypobromite solution. The reaction (and its perchlorate analogue) occurs naturally, but very slowly, requiring several days to complete.[9]

Diperiodatonickelate anions in alkaline solution can oxidise bromate to perbromate. This is a relatively lower cost and fluorine free synthesis.[10]

See also

Other bromine anions:

Bromine oxidation state −1 +1 +3 +5 +7
Name bromide hypobromite
bromite
 bromate perbromate
Formula Br− BrO− BrO−
2 		BrO−
3 		BrO−
4
Structure The bromide ion The hypobromite ion The bromite ion The bromate ion The perbromate ion

References

  1. ISBN 0-12-352651-5
    .
  2. ^
    ISBN 0-85404-617-8
    .
  3. ^
    ISBN 0-8493-0256-0
    .
  4. doi:10.1021/ar50064a001
    .
  5. ^ a b Appelman, E. H. (1968). "Synthesis of perbromates". Journal of the American Chemical Society. 90 (7): 1900–1901.
    doi:10.1021/ja01009a040
    .
  6. ISBN 0-7487-6420-8
    .
  7. ISBN 0-12-352651-5
    .
  8. ^
    doi:10.1021/ic50072a008
    .
  9. ^ Pisarenko, Aleksey N.; Young, Robert; Quiñones, Oscar; J. Vanderford, Brett; B. Mawhinney, Douglas (2011). "Two New Methods of Synthesis for the Perbromate Ion: Chemistry and Determination by LC-MS/MS". Inorg. Chem. 50 (18): 8691–8693.
    PMID 21780765
    .
  10. doi:10.1080/1028662021000020244
    .
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