Aketyl group inorganic chemistry is ananionradical that contains a group R2C−O•. It is the product of the 1-electron reduction of a ketone.
Anothermesomeric structure has the radical position on carbon and the negative charge on oxygen.[1]
Ketyls can be formed asradical anions byone-electron reduction ofcarbonyls withalkali metals. Sodium and potassium metal reduce benzophenone inTHF solution to the soluble ketyl radical. Ketyls are also invoked as intermediates in thepinacol coupling reaction.
The ketyl radicals derived from the reaction ofsodium andbenzophenone is a common laboratorydesiccant. Ketyls react quickly with water, peroxides, and with oxygen. Thus, the deep purple coloration qualitatively indicates dry, peroxide-free, and oxygen-free conditions. The method for drying is still popular in many laboratories due to its ability to produce such pure solvent quickly. An alternative option for chemists interested only in water-free solvent is the use ofmolecular sieves. This is a much safer method than using an alkali metal still, produces solvent as dry as sodium-ketyl (though not as dry as potassium, or potassium-sodium alloy) but takes longer.[2]
Sodium benzophenone ketyl reacts with oxygen to givesodium benzoate andsodium phenoxide.
Potassium-benzophenone ketyl is used as a reductant for the preparation of organoiron compounds.[3]
When excess alkali metal is present, benzophenone ketyl may be reduced to the ketone dianion, resulting in a color transformation from deep blue to purple:[4]: 899–900