Potassium fluoride
[CAS# 7789-23-3]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal halides and halides >> Metal fluorides and salts
• Name: Potassium fluoride
• Molecular Formula: KF
• Molecular Weight: 58.09
• CAS Registry Number: 7789-23-3
• EC Number: 232-151-5
• SMILES: [F-].[K+]

Properties

• Density: 2.48 g/mL (Expl.)
• Melting point: 858 ºC (Expl.)
• Boiling point: 1505 ºC (Expl.)
• Solubility: water 96g/100mL (21 ºC) (Expl.)
• Refraction index: 1.363 (Expl.)

Safety Data

• Hazard Symbols: GHS06 Danger
• Hazard Statements: H301-H311-H331
• Precautionary Statements: P261-P262-P264-P270-P271-P280-P301+P316-P302+P352-P304+P340-P316-P321-P330-P361+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	3	H331
Serious eye damage	Eye Dam.	1	H318
Skin corrosion	Skin Corr.	1C	H314
Reproductive toxicity	Repr.	2	H361
Specific target organ toxicity - repeated exposure	STOT RE	1	H372
Acute toxicity	Acute Tox.	2	H330
Germ cell mutagenicity	Muta.	2	H341
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315

• Transport Information: UN 1812

Discovory and Applicatios

Potassium fluoride is an inorganic compound with the chemical formula KF. It consists of potassium cations (K⁺) and fluoride anions (F^–), forming a white crystalline solid that is highly soluble in water. Because of its ionic nature, KF is hygroscopic and readily absorbs moisture from the air.

The compound was first studied in the early 19th century during systematic research into alkali metal salts and their halide derivatives. Its preparation typically involved neutralizing hydrofluoric acid with potassium carbonate or potassium hydroxide, producing potassium fluoride along with water or carbon dioxide as byproducts. The reaction of potassium with elemental fluorine can also yield KF, although this is less common due to the extreme reactivity of fluorine.

One of the major applications of potassium fluoride is in organic synthesis, where it serves as a source of fluoride ions. Fluoride is a versatile nucleophile, and KF is used in substitution and elimination reactions, including the preparation of organofluorine compounds. Compared to hydrofluoric acid, KF is easier to handle, though it retains significant toxicity and corrosiveness due to its ability to liberate HF upon contact with moisture.

In industrial chemistry, potassium fluoride is utilized as a flux in metal processing, especially in aluminum and steel refining, where it helps reduce melting temperatures and remove impurities. It is also applied in glass etching and ceramics manufacturing because of its ability to attack silica and silicate structures.

Potassium fluoride is further employed in the production of specialty chemicals, including fluorosilanes and fluorophosphates, which serve as intermediates in pharmaceuticals, agrochemicals, and advanced materials. In some applications, KF is supported on alumina or other inert carriers to create heterogeneous catalysts that enhance selectivity in fluorination reactions.

Due to its solubility and ability to generate HF upon hydrolysis, potassium fluoride must be handled with care. Exposure can cause severe irritation to the skin, eyes, and respiratory tract, and ingestion is highly toxic. Industrial and laboratory use requires protective measures such as gloves, goggles, and fume hoods to ensure safe handling.

Overall, potassium fluoride is a fundamental inorganic salt whose reactivity and role as a fluoride source have made it indispensable in synthesis, metallurgy, ceramics, and materials science. Its chemistry illustrates the balance between utility and hazard in working with reactive halide compounds.

References

2019. Four-component green synthesis of benzochromene derivatives using nano-KF/clinoptilolite as basic catalyst: study of antioxidant activity. Molecular Diversity, 23(2).
DOI: 10.1007/s11030-019-09935-6

2008. Facile Hydrolysis-Based Chemical Destruction of the Warfare Agents VX, GB, and HD by Alumina-Supported Fluoride Reagents. The Journal of Organic Chemistry, 74(1).
DOI: 10.1021/jo8019972

2014. Mathematical study of the thermoluminescence process in K2YF5:Tb3+. Radiation Protection Dosimetry, 163(3).
DOI: 10.1093/rpd/ncu364