Potassium fluoride

Potassium fluoride
Names
	IUPAC name Potassium fluoride
Identifiers
CAS Number	7789-23-3 (anhydrous) ; 13455-21-5 (dihydrate) ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL1644027 ;
ChemSpider	23006 ;
ECHA InfoCard	100.029.228
EC Number	232-151-5;
PubChem CID	522689;
RTECS number	TT0700000;
UNII	9082WG1G3F ; 95R1D12HEH (dihydrate) ;
CompTox Dashboard (EPA)	DTXSID8031940 ;
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Properties
Chemical formula	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)
Solubility in water	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
Magnetic susceptibility (χ)	−23.6·10−6 cm3/mol
Structure
Crystal structure	cubic
Hazards
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H301, H311, H331
GHS precautionary statements	P261, P264, P270, P271, P280, P301+310, P302+352, P304+340, P311, P312, P321, P322, P330, P361, P363, P403+233, P405, P501
NFPA 704 (fire diamond)	3 0 0
Flash point	Non-flammable
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	245 mg/kg (oral, rat)
Related compounds
Other anions	Potassium chloride; Potassium bromide; Potassium iodide
Other cations	Lithium fluoride; Sodium fluoride; Rubidium fluoride; Caesium fluoride; Francium fluoride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

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 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↑

Platinum or heat resistant plastic containers are often used for these operations.

Potassium chloride converts to KF upon treatment with hydrogen fluoride. In this way, potassium fluoride is recyclable.^[3]

Crystalline properties[]

KF crystallizes in the cubic NaCl crystal structure. The lattice parameter at room temperature is 0.266 nm.^[4]

Applications in organic chemistry[]

In organic chemistry, KF can be used for the conversion of chlorocarbons into fluorocarbons, via the Finkelstein (alkyl halides)^[5] and Halex reactions (aryl chlorides).^[3] Such reactions usually employ polar solvents such as dimethyl formamide, ethylene glycol, and dimethyl sulfoxide.^[6] More efficient fluorination of aliphatic halides can be achieved with a combination of crown ether and bulky diols in acetonitrile solvent.^[7]

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[]

^ "Potassium Fluoride". sigmaaldrich.com. Retrieved 2018-12-20.
^ Chambers, Michael. "ChemIDplus - 7789-23-3 - NROKBHXJSPEDAR-UHFFFAOYSA-M - Potassium fluoride - Similar structures search, synonyms, formulas, resource links, and other chemical information". chem.sis.nlm.nih.gov.
^ Jump up to: ^a ^b Siegemund, Günter; Schwertfeger, Werner; Feiring, Andrew; Smart, Bruce; Behr, Fred; Vogel, Herward; McKusick, Blaine (2002). "Fluorine Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_349..
^ "Potassium fluoride". University College London.
^ Vogel, A. I.; Leicester, J.; Macey, W. A. T. (1956). "n-Hexyl Fluoride". Organic Syntheses. 36: 40. doi:10.15227/orgsyn.036.0040.
^ 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
^ Silva, Samuel L.; Valle, Marcelo S.; Pliego, Josefredo R. (2020-12-04). "Nucleophilic Fluorination with KF Catalyzed by 18-Crown-6 and Bulky Diols: A Theoretical and Experimental Study". The Journal of Organic Chemistry. 85 (23): 15457–15465. doi:10.1021/acs.joc.0c02229. ISSN 0022-3263.

[1] "Potassium Fluoride". sigmaaldrich.com. Retrieved 2018-12-20.

[2] Chambers, Michael. "ChemIDplus - 7789-23-3 - NROKBHXJSPEDAR-UHFFFAOYSA-M - Potassium fluoride - Similar structures search, synonyms, formulas, resource links, and other chemical information". chem.sis.nlm.nih.gov.

[Ull-3] Jump up to: ^a ^b Siegemund, Günter; Schwertfeger, Werner; Feiring, Andrew; Smart, Bruce; Behr, Fred; Vogel, Herward; McKusick, Blaine (2002). "Fluorine Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_349..

[4] "Potassium fluoride". University College London.

[5] Vogel, A. I.; Leicester, J.; Macey, W. A. T. (1956). "n-Hexyl Fluoride". Organic Syntheses. 36: 40. doi:10.15227/orgsyn.036.0040.

[6] 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

[7] Silva, Samuel L.; Valle, Marcelo S.; Pliego, Josefredo R. (2020-12-04). "Nucleophilic Fluorination with KF Catalyzed by 18-Crown-6 and Bulky Diols: A Theoretical and Experimental Study". The Journal of Organic Chemistry. 85 (23): 15457–15465. doi:10.1021/acs.joc.0c02229. ISSN 0022-3263.

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