Characteristic

 

Caesium fluoride or cesium fluoride is an inorganic compound with the formula CsF. It is a hygroscopic white solid. Caesium fluoride can be used in organic synthesis as a source of the fluoride anion. Caesium has the highest electropositivity of all non-radioactive elements and fluorine has the highest electronegativity of all elements.

Chemical formula: CsF

Molar mass: 151.903 g/mol

Appearance:  white crystalline solid

Density: 4.64 g/cm³

Melting point: 703 °C (1,297 °F; 976 K)

Boiling point: 1,251 °C (2,284 °F; 1,524 K)

Solubility in water: 573.0 g/100 mL (25 °C)

Solubility: Insoluble in acetone, diethyl ether, pyridine and ethanol

191 g/100 mL in methanol.

Magnetic susceptibility (χ): -44.5•10−6 cm³/mol

Refractive index (nD): 1.477

 

Application

 

Cesium fluoride is used for desilylation reactions in organic synthesis. Useful base in organic chemistry, due to its low nucleophilicity. Owing to its high ionic character, it is a very reactive source of fluoride ion in organic synthesis. Reagent of choice when reactive "naked" fluoride is required. Effective catalyst in promoting Knoevenegal condensation. Single crystals of CsF are useful as the windows of cells for infrared spectroscopy.