potassium bromate

Potassium bromate is produced when bromine is passed through a hot solution of potassium hydroxide. This first forms unstable potassium hypobromite, which quickly disproportionates into bromide and bromate:{{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}}

: 3 {{chem|BrO|−}} $\backslash \; \backslash xrightarrow\{\backslash mathsf\{\backslash \; (aq)\backslash ;\}\}\backslash$ 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 chlorates.{{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.

As established by X-ray crystallography, the O-Br-O angles are 104.5°, consistent with its pyramidal shape of the anion. The Br-O distances are 1.66 Å.

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.{{cite report |section=Volume 13, Series 6, page 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}} 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.{{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 }}

Potassium bromate may be used in the production of malt barley, but under safety conditions prescribed by the U.S. Food and Drug Administration (FDA), including labeling standards for the finished product.{{cite report |at=section 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=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}} It is a powerful oxidizer (electrode potential $E^\backslash ominus$ {{nobr|{{math|{{=}} 1.5}} volts,}} similar to potassium permanganate).{{citation needed|date=June 2021}}

Potassium bromate is classified as a category 2B carcinogen by the IARC.

{{cite report |url=http://www.inchem.org/documents/iarc/vol73/73-17.html |title=Potassium bromate (group 2B) |publisher=International Agency for Research on Cancer (IARC) |volume=73 |id=73-17 |via=inchem.org |series=IARC Summaries & Evaluations}}

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.

{{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

{{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}}

Potassium bromate is banned from food products in the European Union, Argentina, Brazil,

{{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

}}

Canada, Nigeria, South Korea, and Peru. It was banned in Sri Lanka in 2001,{{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

}} China in 2005,

{{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

}}

and India in 2016,

{{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

}}

but it is allowed in most of the United States. As of May 2023, the U.S. state of New York is considering banning the use of potassium bromate.

{{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

}}

In California, a warning label is required when bromated flour is used.

{{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 65 |publisher=California Office of Environmental Health Hazard Assessment |department=CRNR notices}}

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.{{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}}{{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}}

{{cite news

|title = California becomes first U.S. state to ban 4 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

}}

{{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