Potassium tert-butoxide

Potassium t-butoxide is commercially available as a solution and as a solid, but it is often generated in situ for laboratory use because samples are so moisture-sensitive and older samples are often of low purity. It is prepared by the reaction of dry tert-butyl alcohol with potassium metal. The solid is obtained by evaporating these solutions followed by heating the solid. The solid can be purified by sublimation. ==Structure==

It crystallizes as a tetrameric cubane-type cluster. It crystallises from tetrahydrofuran/pentane at −20 °C as [tBuOK·tBuOH]∞, which consists of straight chains linked by hydrogen bonding. Sublimation of [tBuOK·tBuOH]∞ affords the tetramer [tBuOK]4, which adopts a cubane-like structure. Mildly Lewis basic solvents such as THF and diethyl ether do not break up the tetrameric structure, which persists in the solid, in solution and even in the gas phase. ==Reactions==

As a base Many modifications have been reported that influence the reactivity of this reagent. The compound adopts a complex cluster structure (the adjacent picture is a simplified cartoon), and additives that modify the cluster affect the reactivity of the reagent. For example, DMF, DMSO, hexamethylphosphoramide (HMPA), and 18-crown-6 interact with the potassium center, yielding solvent separated ion pairs such as K(DMSO)x+ and tert-BuO−. Whereas in benzene, on the other hand, the compound remains as a cluster structure, which is less basic. Potassium tert-butoxide can abstract a beta-proton from alkylammonium cations, leading to the Hofmann product via an elimination reaction. Other reactions Potassium tert-butoxide catalyzes the reaction of hydrosilanes and heterocyclic compounds to give the silyl derivatives, with release of H2. ==Safety==

Potassium tert-butoxide is a very strong base that rapidly attacks living tissue. Potassium tert-butoxide forms explosive mixtures when treated with dichloromethane. ==Related compounds==

• Sodium tert-butoxide • Lithium tert-butoxide ==References==