In
chemistry, the perbromate ion is the
anion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
having the chemical formula . It is an
oxyanion An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determine ...
of
bromine
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simil ...
, the
conjugate base
A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...
of
perbromic acid, in which bromine has the
oxidation state
In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. ...
+7.
Unlike its chlorine () and iodine ()
analogs
Analog or analogue may refer to:
Computing and electronics
* Analog signal, in which information is encoded in a continuous variable
** Analog device, an apparatus that operates on analog signals
*** Analog electronics, circuits which use analog ...
, it is difficult to synthesize.
It has
tetrahedral molecular geometry
In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1(−) = 109.4712206...° ≈ 109.5° when all four substituents are ...
.
The term perbromate also refers to a compound that contains the anion or the
functional group
In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the res ...
.
The perbromate ion is a strong oxidizing agent.
The reduction potential for the /
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
beta decay
In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For e ...
of
selenium-83 in a
selenate salt:
: → + β
−
Subsequently, it was successfully synthesized again by the
electrolysis of , although only in low yield.
[
] Later, it was obtained by the oxidation of
bromate
The bromate anion, BrO, is a bromine-based oxoanion. A bromate is a chemical compound that contains this ion. Examples of bromates include sodium bromate, (), and potassium bromate, ().
Bromates are formed many different ways in municipal drin ...
with
xenon difluoride
Xenon difluoride is a powerful fluorinating agent with the chemical formula , and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherwi ...
.
Once perbromates are obtained,
perbromic acid can be produced by protonating .
One effective method of producing perbromate is by the oxidation of
bromate
The bromate anion, BrO, is a bromine-based oxoanion. A bromate is a chemical compound that contains this ion. Examples of bromates include sodium bromate, (), and potassium bromate, ().
Bromates are formed many different ways in municipal drin ...
with
fluorine under alkaline conditions:
: + + 2 → + 2 +
This synthesis is much easier to perform on a large scale than the electrolysis route or oxidation by xenon difluoride.
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.
[
]
Diperiodatonickelate anions in alkaline solution can oxidise bromate to perbromate. This is a relatively lower cost and fluorine free synthesis.
See also
Other bromine anions:
References
{{Reflist
Perbromates