Tetrahydroxyborate

From Wikipedia, the free encyclopedia
Tetrahydroxyborate
Stereo, skeletal formula of tetrahydroxyborate with a dimension
Ball and stick model of tetrahydroxyborate
Names
IUPAC name
Tetrahydroxyborate
Systematic IUPAC name
Tetrahydroxyboranuide[1] (substitutive)
Tetrahydroxidoborate(1-)[1] (additive)
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
1966
Properties
H4BO4−
Molar mass 78.840 g mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N  (what is checkY☒N ?)
Infobox references

Tetrahydroxyborate (systematically named tetrahydroxyboranuide and tetrahydroxidoborate(1−)) is an inorganic anion with the chemical formula [B(OH)
4]−
 (also written as B(OH)−
4 or BH
4O−
4). It contributes no colour to tetrahydroxyborate salts. It is found in the mineral hexahydroborite, Ca(B(OH)4)2 • 2H2O (originally formulated CaB2O4 • 6H2O).[2] It is classified as a weak base.

Chemical properties[]

Basicity[]

Tetrahydroxyborate can assimilate a proton into the anion by recombination:

B(OH)−
4 +  H+ → B(OH)
3 + H
2O

 

 

 

 

(1)

Because of this capture of a proton (H+
), tetrahydroxyborate has Arrhenius-basic character. Its protonation product is boric acid. In aqueous solution, most tetrahydroxyborate ions are undissociated.[citation needed]

B(OH)−
4 B(OH)
3 +  OH−

 

 

 

 

(2)

Structure[]

It is a boron oxoanion with a tetrahedral geometry.[3] It is isoelectronic with the hypothetical compound orthocarbonic acid.

Chemical reactions[]

Tetrahydroxyborate undergoes the typical chemical reactions of a hydroxyborate. Upon treatment with a standard acid, it converts to boric acid and a metal salt. Oxidation of tetrahydroxyborate gives perborate. When heated to a high temperature, tetrahydroxyborate salts decompose to produce metaborate salts and water, or to produce boric acid and a metal hydroxide:

n [B(OH)4]− → (BO−
2)n + 2n H
2O
[B(OH)4]− → B(OH)3 + HO−

Production[]

Tetrahydroxyborate is produced by boric acid alkalinisation. In this process boric acid and hydroxide anions react to produce tetrahydroxyborate according to the following reaction:

B(OH)3 + HO− → [B(OH)4]−

This process also involves aquatrihydroxyboron as an intermediate, and occurs in two steps. No catalyst is needed for alkalinisation (step 2).

  1. B(OH)3 + H
    2    O     → [B(OH)3H2O]
  2. [B(OH)3H2O] + HO− → [B(OH)4]− + H
    2    O

Catalytic amounts of water are used for the process. By altering the process conditions, other borate anions may also be produced on the same production site.

Uses[]

Tetrahydroxyborate can be used as a cross-link in polymers.

Occurrence[]

The tetrahydroxyborate anion is found in Na[B(OH)4],[4] Na2[B(OH)4]Cl and CuII[B(OH)4]Cl.

See also[]

References[]

  1. ^ Jump up to: a b "Tetrahydroxoborate(1−) (CHEBI:41132)". Chemical Entities of Biological Interest (ChEBI). UK: European Bioinformatics Institute.
  2. ^ Glossary of Geology,5th edition, 2005, ISBN 978-0922152766 ed. by Julia A. Jackson, James P. Mehl, Klaus K. E. Neuendorf, American Geological Institute
  3. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 203–205. ISBN 978-0-08-037941-8.
  4. ^ L. J. Csetenyi; F. P. Glasser; R. A. Howie (June 1993). "Structure of sodium tetrahydroxyborate". Acta Crystallogr. C. 49 (6): 1039–1041. doi:10.1107/S0108270193000058.
Retrieved from ""