Potassium bromate

Potassium bromate

Names
IUPAC name Potassium bromate
Other names Potassium bromate(V) Bromic acid potassium salt
Identifiers
CAS Registry Number	7758-01-2 Y
ChEBI	CHEBI:38211 Y
ChemSpider	22852 Y
EC number	231-829-8
InChI InChI=1S/BrHO3.K/c2-1(3)4;/h(H,2,3,4);/q;+1/p-1 Y Key: OCATYIAKPYKMPG-UHFFFAOYSA-M Y InChI=1/BrHO3.K/c2-1(3)4;/h(H,2,3,4);/q;+1/p-1 Key: OCATYIAKPYKMPG-REWHXWOFAM
Jmol-3D images	Image
KEGG	C19295 N
PubChem	23673461
RTECS number	EF8725000
SMILES [K+].[O-]Br(=O)=O
UN number	1484
Properties
Chemical formula	KBrO3
Molar mass	167.00 g/mol
Appearance	white crystalline powder
Density	3.27 g/cm3
Melting point	350 °C (662 °F; 623 K)
Boiling point	370 °C (698 °F; 643 K) (decomposes)
Solubility in water	3.1 g/100 mL (0 °C) 6.91 g/100 mL (20 °C) 13.3 g/100 mL (40 °C) 49.7 g/100 mL (100 °C)
Solubility	slightly soluble in alcohol insoluble in acetone, ethanol
Structure
Crystal structure	hexagonal
Thermochemistry
Std enthalpy of formation (ΔfHo298)	-342.5 kJ/mol
Hazards
MSDS	ICSC 1115
EU Index	035-003-00-6
EU classification	Carc. Cat. 2 Toxic (T) Oxidant (O)
R-phrases	R45 R9 R25
S-phrases	S53 S45
NFPA 704	0 2 2 OX
Flash point	Non-flammable
LD50 (Median lethal dose)	157 mg/kg (oral, rat)[1]
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Potassium bromate (KBrO₃), is a bromate of potassium and takes the form of white crystals or powder.

Preparation

Potassium bromate is produced by passing bromine into a solution of potassium hydroxide. An industrial electrolytic process is used for large scale production.

Alternatively, it can be created as a by-product of potassium bromide production by absorption of bromine from ocean water into potassium carbonate.

Uses in baking

Although banned for use in foods by many countries, in the USA Potassium bromate is typically used 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, will be completely used up in the baking bread. However, if too much is added, or if the bread is not baked long enough or not at a high enough temperature, then a residual amount will remain, which may be harmful if consumed . Potassium bromate might also be used in the production of malt barley where the U.S. Food and Drug Administration (FDA) has prescribed certain conditions where it may be used safely, which includes labeling standards for the finished malt barley product.^[2] It is a very powerful oxidizer (E° = 1.5 volts comparable to potassium permanganate).

Regulation

Potassium bromate is classified as a category 2B carcinogen (possibly carcinogenic to humans) by the International Agency for Research on Cancer (IARC).^[3]

Potassium bromate has been banned from use in food products in the EU, Canada, Nigeria, Brazil,^[4] South Korea, Peru and some other countries. It was banned in Sri Lanka in 2001^[5] and China in 2005.

In the United States of America, it has not been banned. The FDA sanctioned 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. But since 1991 the FDA has urged bakers to voluntarily stop using it. In California a warning label is required when bromated flour is used.^[6]

Japanese baked goods manufacturers stopped using potassium bromate voluntarily in 1980; however, Yamazaki Baking resumed its use in 2005, claiming they had new production methods to reduce the amount of the chemical which remained in the final product.^[7]

References