Perbromate
{{Short description|Ion}}
{{Chembox
|ImageFile=Perbromate-3D-vdW.png
|ImageCaption=Space-filling model of the perbromate anion, {{chem2|BrO4-}}
|Section1={{Chembox Identifiers
| CASNo = 16474-32-1
| CASNo_Ref = {{Cascite|changed|PubChem}}
| ChEBI = 29246
| ChemSpiderID = 4574125
| PubChem = 5460630
| StdInChI=1S/BrHO4/c2-1(3,4)5/h(H,2,3,4,5)/p-1
| StdInChIKey = LLYCMZGLHLKPPU-UHFFFAOYSA-M
| SMILES = [O-]Br(=O)(=O)=O
}}
|Section2={{Chembox Properties
| Formula_Charge=−
| Br=1|O=4
}}
|Section8={{Chembox Related
|OtherCompounds=bromide
hypobromite
bromite
bromate
}}
}}
In chemistry, the perbromate ion is the anion with the chemical formula {{chem2|BrO4-}}. It is an oxyanion of bromine, the conjugate base of perbromic acid, in which bromine has the oxidation state +7.{{Cite book
| title = Inorganic chemistry
| author1 = Egon Wiberg
| author2 = Nils Wiberg
| author3 = Arnold Frederick Holleman
| publisher = Academic Press
| year = 2001
| isbn = 0-12-352651-5
| page = 439
}} Unlike its chlorine ({{chem2|link=perchlorate|ClO4-}}) and iodine ({{chem2|link=periodate|IO4-}}) analogs, it is difficult to synthesize. It has tetrahedral molecular geometry.
The term perbromate also refers to a compound that contains the {{chem2|BrO4-}} anion or the {{chem2|\sOBrO3}} functional group.
The perbromate ion is a strong oxidizing agent. The reduction potential for the {{chem2|BrO4-}}/bromide 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 beta decay of selenium-83 in a selenate salt:{{Cite journal | doi = 10.1021/ar50064a001 | title = Nonexistent compounds. Two case histories | year = 1973 | last1 = Appelman | first1 = E. H. | journal = Accounts of Chemical Research | volume = 6 | issue = 4| pages = 113–117 }}
:{{chem|83|SeO|4|2−}} → {{chem|83|BrO|4|−}} + β−
Subsequently, it was successfully synthesized again by the electrolysis of {{Chem|LiBrO|3}}, although only in low yield.
{{Cite journal
| doi = 10.1021/ja01009a040
| title = Synthesis of perbromates
| year = 1968
| last1 = Appelman
| first1 = E. H.
| journal = Journal of the American Chemical Society
| volume = 90
| issue = 7
| pages = 1900–1901
| title = Introduction to modern inorganic chemistry
| author1 = Kenneth Malcolm Mackay
| author2 = W. Henderson
| editor = Rosemary Ann Mackay
| edition = 6th
| publisher = CRC Press
| year = 2002
| isbn = 0-7487-6420-8
| page = 488
}} Later, it was obtained by the oxidation of bromate with xenon difluoride.{{Cite book | title = High temperature properties and thermal decomposition of inorganic salts with oxyanions | author = Kurt H. Stern | publisher = CRC Press | year = 2001 | isbn = 0-8493-0256-0 | page = 224}}{{Cite book | title = Inorganic chemistry | author1 = Egon Wiberg | author2 = Nils Wiberg | author3 = Arnold Frederick Holleman | publisher = Academic Press | year = 2001 | isbn = 0-12-352651-5 | page = 395 }} Once perbromates are obtained, perbromic acid can be produced by protonating {{Chem|BrO|4|-}}.
One effective method of producing perbromate is by the oxidation of bromate with fluorine under alkaline conditions:{{Cite book
| title = Main group chemistry (Volume 3 of Tutorial chemistry texts)
| author = W. Henderson
| publisher = Royal Society of Chemistry
| year = 2000
| isbn = 0-85404-617-8
| pages = 136–137
:{{Chem|BrO|3|-}} + {{Chem|F|2}} + 2 {{Chem|OH|-}} → {{Chem|BrO|4|-}} + 2 {{Chem|F|-}} + {{Chem|H|2|O}}
This synthesis is much easier to perform on a large scale than the electrolysis route or oxidation by xenon difluoride.{{cite journal | last1 = Appelman | year = 1969 | first1 = E. H. | title = Perbromic acid and perbromates: synthesis and some properties | journal = Inorg. Chem. | volume = 8 | issue = 2 | pages = 223–227 | doi = 10.1021/ic50072a008 }}
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.
{{cite journal
|first1=Aleksey N.|last1=Pisarenko|first2=Robert |last2=Young|first3=Oscar |last3=Quiñones|first4=Brett |last4=J. Vanderford|first5=Douglas |last5=B. Mawhinney
|title=Two New Methods of Synthesis for the Perbromate Ion: Chemistry and Determination by LC-MS/MS| journal = Inorg. Chem.|year=2011|volume=50|issue=18|pages=8691–8693|doi=10.1021/ic201329q |pmid=21780765
}}
Diperiodatonickelate anions in alkaline solution can oxidise bromate to perbromate. This is a relatively lower cost and fluorine free synthesis.{{cite journal|last1=Bilehal|first1=Dinesh C.|last2=Kulkarni|first2=Raviraj M.|last3=Nandibewoor|first3=Sharanappa T.|title=Kinetics and Mechanism of Oxidation of Bromate by Diperiodatonickelate(IV) in Aqueous Alkaline Medium--A Simple Method for Formation of Perbromate|journal=Inorganic Reaction Mechanisms|date=January 2002|volume=4|issue=1–2|pages=103–109|doi=10.1080/1028662021000020244}}
See also
Other bromine anions:
| class="wikitable" |
| Bromine oxidation state
| −1 | +1 | +3 | +5 | +7 |
|---|
| Name
| bromide | bromite | bromate | perbromate |
| Formula
| Br− | BrO− | {{chem|BrO|2|−}} | {{chem|BrO|3|−}} | {{chem|BrO|4|−}} |
| Structure
| File:Hypobromite ion Space Fill.png |
