View source for Potassium bromate

{{short description|Chemical compound}}
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 458438073
| style = 
| Name = 
| ImageFile = Potassium bromate.png
| ImageSize = 150px
| ImageFileL1 = Potassium-3D.png
| ImageFileR1 = Bromate-3D-vdW.png
| ImageFile2 = Bromičnan draselný.JPG
| ImageSize2 = 180px
| IUPACName = Potassium bromate
| OtherNames = {{Unbulleted list|Potassium bromate(V)|Bromic acid, potassium salt}}
| SystematicName = 
| Section1 = {{Chembox Identifiers
| CASNo =7758-01-2
| CASNo_Ref = {{cascite|correct|CAS}}
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22852
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 38211
| ChEMBL = 2311074
| EINECS = 231-829-8
| Gmelin = 15380 
| RTECS = EF8725000
| UNNumber = 1484
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C19295
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 04MB35W6ZA
| PubChem = 23673461
| SMILES = [K+].[O-]Br(=O)=O
| InChI = 1/BrHO3.K/c2-1(3)4;/h(H,2,3,4);/q;+1/p-1
| InChIKey = OCATYIAKPYKMPG-REWHXWOFAM
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/BrHO3.K/c2-1(3)4;/h(H,2,3,4);/q;+1/p-1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = OCATYIAKPYKMPG-UHFFFAOYSA-M
  }}
| Section2 = {{Chembox Properties
| Formula = {{chem|K|Br|O|3}}
| MolarMass =167.00 g/mol
| Appearance =white crystalline powder
| Density =3.27 g/cm³
| MeltingPtC =350
| BoilingPtC = 370
| BoilingPt_notes = (decomposes)
| Solubility = 3.1 g/100 mL (0 °C) <br> 6.91 g/100 mL (20 °C)<br> 13.3 g/100 mL (40 °C) <br> 49.7 g/100 mL (100 °C)
| SolubleOther = Insoluble in [[acetone]]
| MagSus = −52.6·{{10^|−6}} cm³/mol
  }}
| Section3 = {{Chembox Structure
| CrystalStruct = hexagonal
  }}
| Section4 = {{Chembox Thermochemistry
| DeltaHf = −342.5 kJ/mol
}}
| Section5 = {{Chembox Hazards
| ExternalSDS = {{cite web |title=ICSC&nbsp;1115 |url=http://www.inchem.org/documents/icsc/icsc/eics1115.htm}}
| NFPA-H = 3
| NFPA-F = 0
| NFPA-R = 2
| NFPA-S = OX
| FlashPt = Non-flammable
| GHSPictograms = {{GHS03}}{{GHS06}}{{GHS08}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|271|301|350}}
| PPhrases = {{P-phrases|201|202|210|220|221|264|270|280|281|283|301+310|306+360|308+313|321|330|370+378|371+380+375|405|501}}
| LD50 = 157 mg/kg (oral, rat)<ref>{{cite web | title = Potassium bromate | id = {{sc|rn}}&nbsp;7758-01-2 | series = ChemIDplus | website = chem.sis.nlm.nih.gov | publisher = U.S. [[National Institutes of Health]]  | url = https://chem.nlm.nih.gov/chemidplus/rn/7758-01-2}}</ref>
  }}
| Section9 = {{Chembox Related
| OtherAnions = [[Potassium chlorate]]<br/>[[Potassium iodate]]
| OtherCations = [[Sodium bromate]]<br/>[[Calcium bromate]]
| OtherFunction = 
| OtherFunction_label = 
| OtherCompounds = 
}}
}}
'''Potassium bromate''' ({{chem|K|Br|O|3}}) is a [[bromate]] of [[potassium]] and takes the form of white crystals or powder. It is a strong oxidizing agent.

==Preparation==
Potassium bromate is produced when [[bromine]] is passed through a hot solution of [[potassium hydroxide]]. This first forms unstable [[potassium hypobromite]], which quickly [[disproportionate]]s into bromide and bromate:<ref name=HarvWestl-AP>{{cite report |title=Synthesis, separation, and purification of {{chem|K|Br}} and {{chem|K|Br|O}} |type=course notes |series=Advanced Placement Chemistry |department=Pre-Labs |publisher=[[Harvard-Westlake School]] |url=http://www.hwscience.com/chemistry/ap/aplab/synkbr.pdf |via=Harvard-Westlake School (hwscience.com) |access-date=14 September 2016 |archive-url=https://web.archive.org/web/20170516205449/http://hwscience.com/chemistry/ap/aplab/synkbr.pdf|archive-date=16 May 2017|url-status=dead}}</ref>
: 3 {{chem|BrO|−}} <math>\ \xrightarrow{\mathsf{\ (aq)\;}}\ </math> 2 {{chem|Br|−|}} + {{chem|BrO|3|−}} 
Electrolysis of [[potassium bromide]] solutions will also give bromate. Both processes are analogous to those used in the production of [[chlorate]]s.{{citation needed|date=June 2021}}

Potassium bromate is readily separated from the potassium bromide present in both methods owing to its much lower solubility; when a solution containing potassium bromate and bromide is cooled to 0°C, nearly all bromate will precipitate, while nearly all of the bromide will stay in solution.<ref name=HarvWestl-AP/>

==Uses in baking==
Potassium bromate is typically used in the United States as a [[flour]] improver ([[E number]] E924). It acts to strengthen the [[dough]] and to allow higher rising. It is an [[oxidizing agent]], and under the right conditions, is reduced to [[bromide]] in the baking process.<ref>{{cite report |section=Volume&nbsp;13, Series&nbsp;6, page&nbsp;3136 |title=''Federal Register'' |year=1948 |type=compendium |lang=en |series=Office of the Federal Register, National Archives and Records Service |publisher=General Services Administration |place=Washington, DC |section-url=https://books.google.com/books?id=ZETX9v5n5jYC&dq=potassium+bromate+bromide+baking&pg=PA3136 |via=Google Books}}</ref><ref name=Kurokawa-Maekawa-etal-1990/> However, if too much is added, or if the bread is under-baked long or baked at a low enough temperature, then a residual amount remains, which may be harmful if consumed.<ref name=Kurokawa-Maekawa-etal-1990>{{cite journal |last1=Kurokawa |first1=Y. |last2=Maekawa |first2=A. |last3=Takahashi |first3=M. |last4=Hayashi |first4=Y. |date=1 July 1990 |title=Toxicity and carcinogenicity of potassium bromate – a new renal carcinogen |journal=[[Environmental Health Perspectives]] |volume=87 |pages=309–335 |issn=0091-6765 |pmc=1567851 |pmid=2269236 |doi=10.1289/ehp.9087309|bibcode=1990EnvHP..87..309K }}</ref>

Potassium bromate may be used in the production of [[malt]] barley, but under safety conditions prescribed by the [[Food and Drug Administration (United States)|U.S. Food and Drug Administration]] (FDA), including labeling standards for the finished product.<ref>{{cite report |at=section&nbsp;172.730 |section=Potassium Bromate |title=Food Additives Permitted for Direct Addition to Food for Human Consumption |series=U.S. Code of Federal Regulations |type=laws & regulations |publisher=[[Food and Drug Administration (United States)|U.S. Food and Drug Administration]] |section-url=https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172/subpart-H/section-172.730 |via=ecfr.gov}}</ref> It is a powerful oxidizer ([[standard electrode potential|electrode potential <math>E^\ominus</math>&nbsp;]]{{nobr|{{math|{{=}} 1.5}} volts,}} similar to [[potassium permanganate]]).{{citation needed|date=June 2021}}

==Regulation==
Potassium bromate is classified as a category&nbsp;2B [[carcinogen]] by the [[International Agency for Research on Cancer|IARC]].<ref>
{{cite report |url=http://www.inchem.org/documents/iarc/vol73/73-17.html |title=Potassium bromate (group&nbsp;2B) |publisher=[[International Agency for Research on Cancer]] (IARC) |volume=73 |id=73-17 |via=inchem.org |series=IARC Summaries & Evaluations}}
</ref> The FDA allowed the use of bromate before the [[Delaney clause]] of the [[Food, Drug, and Cosmetic Act]] – which bans potentially carcinogenic substances – went into effect in 1958. Since 1991, the FDA has urged bakers to not use it, but has not mandated a ban. 

Japanese baked goods manufacturers stopped using potassium bromate voluntarily in 1980; however, [[Yamazaki Baking]] resumed its use in 2005, claiming it had new production methods to reduce the amount of the chemical which remained in the final product.<ref>
{{cite news |last1=Kawo |first1=Kuro |display-authors=etal |title=Japan's Yamazaki Baking to use potassium bromate in bread |url= |url-status= |access-date= |publication-date=c. 1990 |series=AsiaPulse News}} Cited by <br />
{{cite journal |last1=Duvvuri |first1=Shreemathi |last2=Panchagnula |first2=Shobharani |date=September–October 2016 |title=Analysis of potassium iodate and potassium bromate in bakery products by electro-analytical techniques |url=http://www.ijtrd.com/papers/IJTRD4278.pdf |journal=International Journal of Trend in Research and Development |volume=3 |issue=5 |pages=412–413 |issn=2394-9333 |via=ijtrd.com}}
</ref>

Potassium bromate is banned from food products in the European Union, Argentina, Brazil,<ref>
{{cite web
 |title = Dispõe sobre o uso do bromato de potássio na farinha e nos produtos de panificação
 |trans-title=Regarding the use of potassium bromate in flour and bakery products  |lang = pt
 |publication-date = c. 2001
 |url = http://www.planalto.gov.br/ccivil_03/Leis/LEIS_2001/L10273.htm
 |via=planalto.gov.br
}}
</ref> Canada, Nigeria, South Korea, and Peru. It was banned in Sri Lanka in 2001,<ref>{{cite news
 |title={{grey|[title not cited]}}
 |periodical=E‑Law Advocate
 |id=(2001)
 |issue=4
 |publisher=Bridges Across Borders
 |quote=Environmental Law Alliance Worldwide
 |url=http://www.elaw.org/news/advocate/default.asp?issue=2001-4
 |url-status=dead
 |access-date=2006-10-10
 |archive-date=2018-05-16
 |archive-url=https://web.archive.org/web/20180516174511/https://www.elaw.org/news/advocate/default.asp?issue=2001-4
 }} {{citation not found|date=October 2023
}}</ref> China in 2005,<ref>
{{cite news
 |title=Importer halts unsafe potato chips from the U.S.
 |date=7 December 2007 
 |newspaper=[[China Daily]]
 |url=https://www.chinadaily.com.cn/china/2007-12/07/content_6304490.htm
 |access-date=2023-02-21 |via=chinadaily.com.cn
}}
</ref> and India in 2016,<ref>
{{cite news
 |title=India bans use of cancer-causing additive, potassium bromate, in bread, other food
 |orig-date=20 June 2016  |date=21 June 2016
 |newspaper=[[The Times of India]]
 |url=http://timesofindia.indiatimes.com/india/India-bans-use-of-cancer-causing-additive-potassium-bromate-in-bread-other-food/articleshow/52836892.cms
 |access-date=20 June 2016 |via=timesofindia.indiatimes.com
}}
</ref> but it is allowed in most of the United States. As of May&nbsp;2023, the U.S. state of [[New York (state)|New York]] is considering banning the use of potassium bromate.<ref>
{{cite news
 |first=Dana G. |last=Smith
 |date=13 April 2023
 |title=Two states have proposed bans on common food additives linked to health concerns
 |newspaper=[[The New York Times]]
 |url=https://www.nytimes.com/2023/04/13/well/eat/food-additive-ban.html
 |via=nytimes.com |access-date=23 May 2023
}}
</ref> 

In [[California]], a warning label is required when bromated flour is used.<ref>
{{cite web |title=Bromate meets the criteria for listing |url=http://www.oehha.ca.gov/prop65/CRNR_notices/admin_listing/intent_to_list/noilbromate.html |archive-url=https://web.archive.org/web/20131203041405/http://www.oehha.ca.gov/prop65/CRNR_notices/admin_listing/intent_to_list/noilbromate.html |archive-date=2013-12-03 |website=oehha.ca.gov |series=Proposition&nbsp;65 |publisher=[[California Office of Environmental Health Hazard Assessment]] |department=CRNR notices}}
</ref> In October 2023, [[California]] enacted a law that banned the manufacture, sale, and distribution of potassium bromate (along with three other additives: [[brominated vegetable oil]], [[propylparaben]], and [[Red 3]]). The law takes effect in 2027. It was the first U.S. state to ban it.<ref>{{Cite news |last=Cimons |first=Marlene |date=2023-10-11 |title=California isn't banning Skittles, but four additives will be removed |url=https://www.washingtonpost.com/wellness/2023/10/11/california-skittles-ban-chemicals-food/ |access-date=2024-08-18 |newspaper=Washington Post |language=en}}</ref><ref>{{cite web|url=https://leginfo.legislature.ca.gov/faces/billCompareClient.xhtml?bill_id=202320240AB418&showamends=false|title=AB-418 The California Food Safety Act.|publisher=[[ca.gov]]|lang=en}}</ref><ref>
{{cite news
 |title = California becomes first U.S. state to ban 4&nbsp;potentially harmful chemicals in food
 |date = 10 October 2023
 |website = [[CNN]]
 |url = https://www.cnn.com/2023/10/09/health/california-governor-bans-red-dye-no-3-wellness/index.html
}}
</ref>

== References ==
{{Reflist}}

{{Potassium compounds}}
{{Bromates}}
{{E number infobox 920-929}}

[[Category:Bromates]]
[[Category:Potassium compounds]]
[[Category:IARC Group 2B carcinogens]]
[[Category:Oxidizing agents]]
[[Category:Food additives]]