Metaboric acid

Last updated
Metaboric acid
Metaboronic acid molecule.png
Metaboric acid Space Fill.png
Names
IUPAC name
Oxoborinic acid
Other names
Metaboric acid
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.033.313 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 236-659-8
121829
PubChem CID
  • InChI=1S/BHO2/c2-1-3/h2H Yes check.svgY
    Key: VGTPKLINSHNZRD-UHFFFAOYSA-N Yes check.svgY
  • O=BO
  • OB1OB(O)OB(O)O1
Properties
B3H3O6
Molar mass 131.45 g·mol−1
Appearancewhite solid
Density 1.784 g cm−3
Melting point 176 °C (349 °F; 449 K)
Acidity (pKa)9.236
Conjugate base Metaborate
Structure
trigonal at B
Hazards
GHS labelling: [1]
GHS-pictogram-exclam.svg
Warning
H315, H319, H335
P261, P305+P351+P338
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Metaboric acid is the name for a family of inorganic compounds with the same empirical formula HBO2. [2] that differ in their molecular structure. They are colourless water-soluble solids formed by the dehydration or decomposition of boric acid.

Contents

Metaboric acid is formally the parent acid of the metaborate anions.

Structure

The main forms of metaboric acid are:

3 B(OH)3(BOH)3O3 + 3 H2O
Conversion of orthorhombic to monoclinic metaboric acid. Orthorhombic metaboric acid.png
Conversion of orthorhombic to monoclinic metaboric acid.

Reactions

When heated above about 170 °C, metaboric acid dehydrates, forming tetraboric acid, also called pyroboric acid (H2B4O7): [6] [7]

4 HBO2 → H2B4O7 + H2O

Metaborates

Metaborates are derivatives of BO2. Like metaboric acid, the metaborates exist with disparate structures. Examples are sodium and potassium metaborates, salts formed by deprotonation of orthorhombic metaboric acid containing the cyclic B3O63− ion and calcium metaborate, Ca(BO2)2, which contains the chain polymeric ion (BO2)n. [2]

Related Research Articles

<span class="mw-page-title-main">Boric acid</span> Weak acid with formula B(OH)₃

Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula B(OH)3. It may also be called hydrogen orthoborate, trihydroxidoboron or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves in water, and occurs in nature as the mineral sassolite. It is a weak acid that yields various borate anions and salts, and can react with alcohols to form borate esters.

A borate is any of a range of boron oxyanions, anions containing boron and oxygen, such as orthoborate BO3−3, metaborate BO−2, or tetraborate B4O2−7; or any salt of such anions, such as sodium metaborate, Na+[BO2] and borax (Na+)2[B4O7]2−. The name also refers to esters of such anions, such as trimethyl borate B(OCH3)3.

Molybdenum trioxide describes a family of inorganic compounds with the formula MoO3(H2O)n where n = 0, 1, 2. These compounds are produced on the largest scale of any molybdenum compound. The anhydrous oxide is a precursor to molybdenum metal, an important alloying agent. It is also an important industrial catalyst. It is a yellow solid, although impure samples can appear blue or green.

<span class="mw-page-title-main">Boron trioxide</span> Chemical compound

Boron trioxide or diboron trioxide is the oxide of boron with the formula B2O3. It is a colorless transparent solid, almost always glassy (amorphous), which can be crystallized only with great difficulty. It is also called boric oxide or boria. It has many important industrial applications, chiefly in ceramics as a flux for glazes and enamels and in the production of glasses.

<span class="mw-page-title-main">Phosphorus pentoxide</span> Chemical compound

Phosphorus pentoxide is a chemical compound with molecular formula P4O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydrating agent.

<span class="mw-page-title-main">Telluric acid</span> Chemical compound (Te(OH)6)

Telluric acid, or more accurately Orthotelluric acid, is a chemical compound with the formula Te(OH)6, often written as H6TeO6. It is a white crystalline solid made up of octahedral Te(OH)6 molecules which persist in aqueous solution. In the solid state, there are two forms, rhombohedral and monoclinic, and both contain octahedral Te(OH)6 molecules, containing one hexavalent tellurium (Te) atom in the +6 oxidation state, attached to six hydroxyl (–OH) groups, thus, it can be called tellurium(VI) hydroxide. Telluric acid is a weak acid which is dibasic, forming tellurate salts with strong bases and hydrogen tellurate salts with weaker bases or upon hydrolysis of tellurates in water. It is used as tellurium-source in the synthesis of oxidation catalysts.

Sodium perborate is chemical compound whose chemical formula may be written NaH2BO4, Na2H4B2O8, or, more properly, [Na+]2[B2O4(OH)4]2−. Its name is sometimes abbreviated as PBS.

Lithium metaborate is a chemical compound of lithium, boron, and oxygen with elemental formula LiBO2. It is often encountered as a hydrate, LiBO2·nH2O, where n is usually 2 or 4. However, these formulas do not describe the actual structure of the solids.

<span class="mw-page-title-main">Phenylboronic acid</span> Chemical compound

Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH)2 where Ph is the phenyl group C6H5-, is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis. Boronic acids are mild Lewis acids which are generally stable and easy to handle, making them important to organic synthesis.

<span class="mw-page-title-main">Sodium metaborate</span> Chemical compound

Sodium metaborate is a chemical compound of sodium, boron, and oxygen with formula NaBO2. However, the metaborate ion is trimeric in the anhydrous solid, therefore a more correct formula is Na3B3O6 or (Na+)3[B3O6]3−. The formula can be written also as Na2O·B2O3 to highlight the relation to the main oxides of sodium and boron. The name is also applied to several hydrates whose formulas can be written NaBO2·nH2O for various values of n.

Barium borate is an inorganic compound, a borate of barium with a chemical formula BaB2O4 or Ba(BO2)2. It is available as a hydrate or dehydrated form, as white powder or colorless crystals. The crystals exist in the high-temperature α phase and low-temperature β phase, abbreviated as BBO; both phases are birefringent, and BBO is a common nonlinear optical material.

Boron phosphate is an inorganic compound with the chemical formula BPO4. The simplest way of producing it is the reaction of phosphoric acid and boric acid. It is a white infusible solid that evaporates above 1450 °C.

<span class="mw-page-title-main">Metaborate</span> Boron-oxygen anion or functional group

A metaborate is a borate anion consisting of boron and oxygen, with empirical formula BO−2. Metaborate also refers to any salt or ester of such anion. Metaborate is one of the boron's oxyanions. Metaborates can be monomeric, oligomeric or polymeric.

Fluorooxoborate is one of a series of anions or salts that contain boron linked to both oxygen and fluorine. Several structures are possible, rings, or chains. They contain [BOxF4−x](x+1)− units BOF32− BO2F23−, or BO3F14−. In addition there can be borate BO3 triangles and BO4 tetrahedrons. These can then be linked by sharing oxygen atoms, and when they do that, the negative charge is reduced. They are distinct from the fluoroborates in which fluorine is bonded to the metals rather than the boron atoms. For example, KBBF, KBe2BO3F2 is a fluoroborate and has more fluorine and oxygen than can be accommodated by the boron atom.

Tetraboric acid or pyroboric acid is a chemical compound with empirical formula H2B4O7. It is a colourless water-soluble solid formed by the dehydration or polymerization of boric acid.

Hexahydroborite is a mineral composed of calcium, boron, oxygen, and hydrogen, with formula CaB2H12O6, more precisely [Ca2+]([B(OH4)])2·2H2O.

Disodium enneaborate is the traditional name for a salt of sodium, boron, oxygen, and hydrogen, with elemental formula Na2B9H22O20 or Na2B9O9·11H2O. It is the sodium borate with the highest boron/sodium ratio.

Trisodium borate is a chemical compound of sodium, boron, and oxygen, with formula Na3BO3, or (Na+)3[BO3]3−. It is a sodium salt of the orthoboric acid B(OH)3.

<span class="mw-page-title-main">Sodium tetrahydroxyborate</span> Chemical compound

Sodium tetrahydroxyborate is a salt of with chemical formula NaH4BO4 or Na+[B(OH)4]. It is one of several sodium borates. At room temperature it is a colorless crystalline solid.

Protactinium compounds are compounds containing the element protactinium. These compounds usually have protactinium in the +5 oxidation state, although these compounds can also exist in the +2, +3 and +4 oxidation states.

References

  1. GHS: Sigma-Aldrich 413453
  2. 1 2 Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN   0-7506-3365-4.
  3. 1 2 H. J. Becher "Metaboric Acid" Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 791.
  4. 1 2 W. H. Zachariasen "The crystal structure of monoclinic metaboric acid" Acta Crystallogr. 1963, vol. 16, pp. 385-389. doi : 10.1107/S0365110X6300102X
  5. 1 2 Freyhardt, C. C.; Wiebcke, M.; Felsche, J. (2000). "The monoclinic and cubic phases of metaboric acid (precise redeterminations)". Acta Crystallogr C. 56 (3): 276–278. doi: 10.1107/S0108270199016042 . PMID   10777918.
  6. Gurwinder Kaur, Shagun Kainth, Rohit Kumar, Piyush Sharma and O. P. Pandey (2021): "Reaction kinetics during non-isothermal solid-state synthesis of boron trioxide via boric acid dehydration." Reaction Kinetics, Mechanisms and Catalysis, volume 134, pages 347–359. doi : 10.1007/s11144-021-02084-8
  7. Siavash Aghili, Masoud Panjepour, and Mahmood Meratian (2018): "Kinetic analysis of formation of boron trioxide from thermal decomposition of boric acid under non-isothermal conditions." Journal of Thermal Analysis and Calorimetry, volume 131, pages 2443–2455. doi : 10.1007/s10973-017-6740-3