Potassium borohydride

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Potassium borohydride
Potassium borohydride 2.png
Names
IUPAC name
Potassium tetrahydroborate
Other names
Potassium tetrahydridoborate
Borate(1-), tetrahydro-, potassium (1:1)
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.033.949 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 237-360-5
PubChem CID
UNII
UN number 1870 (POTASSIUM BOROHYDRIDE)
  • InChI=1S/BH4.K/h1H4;/q-1;+1 Yes check.svgY
    Key: ICRGAIPBTSPUEX-UHFFFAOYSA-N Yes check.svgY
  • [BH4-].[K+]
Properties
K[BH4]
Molar mass 53.94 g·mol−1
Appearancecolorless solid
Density 1.17 g/mL
Melting point 607 °C (1,125 °F; 880 K) decomposes
19g/100g
Solubility in methanol 3.9g/100g
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-acid.svg GHS-pictogram-skull.svg
Danger
H261, H301, H311, H314, H331
P280, P305+P351+P338, P309, P310, P370+P378, P402+P404
Related compounds
Other anions
Potassium hydride
Other cations
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Potassium borohydride, also known as potassium tetrahydroborate, is an inorganic compound with the formula KBH4.

Contents

Preparation

It can be obtained through the reaction of sodium borohydride with aqueous potassium hydroxide in a methanol or water solvent: [1]

NaBH4 + KOH → KBH4 + NaOH

Properties

Potassium is a colorless solid that is stable at room temperature and in an aqueous alkaline solution. [2] Potassium borohydride has a hydrogen desorption temperature of 584 °C, higher than for lithium borohydride or sodium borohydride. [1]

Like the related Na+, Rb+, and Cs+ salts, potassium borohydride crystallizes in a sodium chloride lattice type, space group Fm3m. [3] [4]

As a reagent

Often potassium borohydride behaves similarly to the more common sodium borohydride, but solubility considerations sometimes recommend the potassium salt. One example is the synthesis of potassium trispyrazolylborate (KTp). The procedure involves heating potassium borohydride and pyrazole without a solvent. [5]

KBH4 + 3 C3N2H4 → KHB(C3N2H3)3 + 3 H2

Diborane is produced by treating potassium borohydride with phosphoric acid. [6]

In combination with bismuth trichloride, it forms a reagent for the reduction of nitro group to the hydroxylamine. [7]

References

  1. 1 2 Michael Hirscher (2010). Handbook of Hydrogen Storage New Materials for Future Energy Storage. John Wiley & Sons. p. 122. ISBN   978-3-527-62981-7.
  2. ↑ Şahin, Ömer; Dolaş, Hacer; Özdemir, Mustafa (September 2007). "The effect of various factors on the hydrogen generation by hydrolysis reaction of potassium borohydride". International Journal of Hydrogen Energy. 32 (13): 2330–2336. Bibcode:2007IJHE...32.2330S. doi:10.1016/j.ijhydene.2006.10.052 . Retrieved 21 July 2025.
  3. ↑ . doi:10.1039/c6cs00705h.{{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help)
  4. ↑ Schelter, E. J.; Luck, R. L. (1997). "Potassium Borohydride". Acta Cryst. 55 (12): IUC9900151. doi:10.1107/S010827019909842X . Retrieved 21 July 2025.
  5. ↑ Trofimenko, Swiatoslaw (1970). "Poly(1-pyrazolyl)borates, Their Transition-Metal Complexes, and Pyrazaboles". Inorganic Syntheses. Vol. 12. pp. 99–109. doi:10.1002/9780470132432.ch18. ISBN   9780470132432.
  6. ↑ Norman, Arlan D.; Jolly, William L. (1968). "Diborane". Inorganic Syntheses. Vol. 11. pp. 15–19. doi:10.1002/9780470132425.ch4. ISBN   978-0-470-13170-1.
  7. ↑ Smith, Michael B.; March, Jerry (2007), Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.), New York: Wiley-Interscience, p. 1819, ISBN   978-0-471-72091-1
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