Potassium fluoride

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Potassium fluoride
Names
IUPAC name
Potassium fluoride
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.029.228 Edit this at Wikidata
EC Number
  • 232-151-5
RTECS number
  • TT0700000
UNII
  • InChI=1S/FH.K/h1H;/q;+1/p-1 checkY
    Key: NROKBHXJSPEDAR-UHFFFAOYSA-M checkY
  • InChI=1S/FH.K/h1H;/q;+1/p-1
    Key: NROKBHXJSPEDAR-REWHXWOFAI
  • Key: NROKBHXJSPEDAR-UHFFFAOYSA-M
  • [F-].[K+]
Properties
KF
Molar mass 58.0967 g/mol (anhydrous)
94.1273 g/mol (dihydrate)
Appearance colourless
Density 2.48 g/cm3
Melting point 858 °C (1,576 °F; 1,131 K) (anhydrous)
41 °C (dihydrate)
19.3 °C (trihydrate)
Boiling point 1,502 °C (2,736 °F; 1,775 K)
anhydrous:
92 g/100 mL (18 °C)
102 g/100 mL (25 °C)
dihydrate:
349.3 g/100 mL (18 °C)
Solubility soluble in HF
insoluble in alcohol
Structure
cubic
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
3
0
1
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
245 mg/kg (oral, rat)[1]
Related compounds
Other anions
 Potassium chloride
Potassium bromide
Potassium iodide
Other cations
 Lithium fluoride
Sodium fluoride
Rubidium fluoride
Caesium fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Potassium fluoride is the chemical compound with the formula KF. After hydrogen fluoride, KF is the primary source of the fluoride ion for applications in manufacturing and in chemistry. It is an alkali halide and occurs naturally as the rare mineral carobbiite. Solutions of KF will etch glass due to the formation of soluble fluorosilicates, although HF is more effective.

Preparation

Potassium fluoride is prepared by dissolving potassium carbonate in excess hydrofluoric acid. Evaporation of the solution forms crystals of potassium bifluoride. The bifluoride on heating yields potassium fluoride:

K2CO3 + 4HF → 2KHF2 + CO2↑ + H2O
KHF2 → KF + HF↑

The salt must not be prepared in glass or porcelain vessels as HF and the aqueous solution of KF corrode glass and porcelain. Heat resistant plastic or platinum containers may be used.

Applications in organic chemistry

In organic chemistry, KF can be used for the conversion of chlorocarbons into fluorocarbons, via the Finkelstein reaction.[2] Such reactions usually employ polar solvents such as dimethyl formamide, ethylene glycol, and dimethyl sulfoxide.[3]

Safety considerations

Like other sources of the fluoride ion, F−, KF is poisonous, although lethal doses approach gram levels for humans. It is harmful by inhalation and ingestion. It is highly corrosive, and skin contact may cause severe burns.

References

  1. ^ http://chem.sis.nlm.nih.gov/chemidplus/rn/7789-23-3
  2. ^ Vogel, A. I.; Leicester, J.; Macey, W. A. T. "n-Hexyl Fluoride". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 525.
  3. ^ Han, Q.; Li, H-Y. "Potassium Fluoride" in Encyclopedia of Reagents for Organic Synthesis, 2001 John Wiley & Sons,New York. doi:10.1002/047084289X.rp214
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