Monopotassium phosphite

Ball-and-stick model of the component ions

Names

IUPAC name

Potassium hydrogen phosphonate

Other names

Potassium dihydrogen phosphite; Mono potassium phosphite; Monopotassium dihydrogen phosphite; Potassium phosphite monobasic

Identifiers

CAS Number

13977-65-6^Y

3D model (JSmol)

Interactive image

ECHA InfoCard

100.116.175

PubChem CID

23701737

UNII

59RSS63D8J^Y

CompTox Dashboard (EPA)

DTXSID20884521

InChI

InChI=1S/K.H2O3P/c;1-4(2)3/h;1-2H/q+1;-1
Key: BZHCGFBZBPVRFE-UHFFFAOYSA-N

SMILES

OP(O)[O-].[K+]

Properties

Chemical formula

H₂KO₃P

Molar mass

120.085 g·mol⁻¹

Appearance

white crystals

Density

2.14 g/cm³

Solubility in water

2200 g/L

Solubility

soluble in ethanol

Structure

Crystal structure

monoclinic

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

N verify (what is ^YN ?)

Infobox references

Chemical compound

Monopotassium phosphite is an inorganic compound with the formula KH₂PO₃. A compositionally related compound has the formula H₃PO₃^.2(KH₂PO₃). Both are white solids that consist of salts of the phosphite anion H₂PO₃⁻, the conjugate base of phosphorous acid.^[1]

Phosphites of potassium are used as fungicides (in a loose sense) in agriculture to combat water mold infection. Confusingly, they have also been marketed as fertilizers to avoid a regulatory burden. While perfectly capable to supply potassium to the plant, the phosphorus in phosphite form is unavailable to plants, and may even inhibit the uptake of the normal phosphate form if used in excess.^[2]

References

^ J. Loub (1991). "Crystal Chemistry of Inorganic Phosphites". Acta Crystallogr. B47: 468–473. doi:10.1107/S0108768191002380.
^ Thao; Yamakawa (2008). "Phosphite (phosphorous acid): Fungicide, fertilizer or bio-stimulator?". Soil Science and Plant Nutrition. 55 (2): 228–234. doi:10.1111/j.1747-0765.2009.00365.x. S2CID 95723306.