Caesium fluoride

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Caesium fluoride is an inorganic compound with the formula CsF. It is a white or transparent solid that is highly soluble in water, and it is considered one of the primary sources of the caesium ion in various applications. Caesium fluoride is used in organic chemistry as a source of the fluoride anion for the introduction of fluorine into organic molecules, a process known as fluorination. Due to its high reactivity towards glass, it is often used in the synthesis of organofluorine compounds within stainless steel or nickel reaction vessels.

Properties

Caesium fluoride has a high melting point (about 703°C) and a relatively high boiling point (about 1251°C). It crystallizes in the cubic crystal system, similar to other alkali halides. The ionic nature of CsF provides it with characteristics such as high solubility in water and other polar solvents, making it an excellent source of fluoride ions in solution.

Production

Caesium fluoride can be produced by the reaction of caesium hydroxide (CsOH) with hydrofluoric acid (HF), or by the neutralization of caesium carbonate (Cs2CO3) with hydrofluoric acid. The process yields caesium fluoride as a precipitate, which can then be purified by recrystallization.

Applications

Organic Synthesis

In organic synthesis, caesium fluoride is utilized for its ability to donate fluoride ions, acting as a base or nucleophile in various reactions. It is particularly useful in the deprotection of silyl ether protecting groups, a common step in the synthesis of complex organic molecules.

Nuclear Magnetic Resonance (NMR)

Caesium fluoride is used in Nuclear Magnetic Resonance (NMR) spectroscopy as an external standard for fluorine-19 (^19F) NMR. Its distinct chemical shift allows for the calibration of NMR instruments, ensuring accurate measurement of the chemical environment of fluorine atoms in organic and inorganic compounds.

Optical Materials

Due to its wide transmission range in the ultraviolet (UV) to infrared (IR) regions of the electromagnetic spectrum, caesium fluoride is also used as a component in optical materials. It is particularly valued in the manufacture of windows, lenses, and prisms for UV and IR spectroscopy.

Safety

Caesium fluoride is considered hazardous due to its reactivity and toxicity. It is corrosive to human tissue and can cause severe burns upon contact. Inhalation or ingestion of caesium fluoride can lead to fluoride poisoning, characterized by a range of symptoms from nausea to cardiac arrhythmias. Proper safety precautions, including the use of personal protective equipment (PPE), are essential when handling caesium fluoride.

See Also

• Caesium
• Fluoride
• Inorganic chemistry
• Organic chemistry
• Fluorination