Kaliumtertbutoxide

Kaliumtertbutoxide, commonly known as potassium tert-butoxide (KOtBu; chemical formula KOC(CH3)3), is a strong, non-nucleophilic base used in organic synthesis. It is the potassium salt of tert-butanol and typically appears as a white to off-white solid that is highly moisture- and air-sensitive.

Physical properties and handling: KOtBu is a hygroscopic solid that reacts vigorously with water and carbon dioxide in air. It is typically handled and stored under inert atmosphere in dry containers. It is only sparingly soluble in water but dissolves in many polar aprotic solvents such as THF and DME, where it can act as a homogeneous base for many reactions.

Preparation and availability: Potassium tert-butoxide is commercially available and can be prepared by the reaction of tert-butanol with a strong base (for example, potassium hydride) under dry, controlled conditions, followed by isolation of the solid. It is favored in laboratories for its robustness as a base and its relatively low nucleophilicity due to steric hindrance.

Applications and reactivity: KOtBu is widely used to deprotonate weak carbon acids to form enolates and to promote elimination (E2) reactions. It is also employed to generate carbanions for nucleophilic substitution and to initiate or participate in various polymerization and rearrangement processes. Its bulky tert-butoxide group makes it less prone to side reactions compared with less hindered alkoxide bases.

Safety: Potassium tert-butoxide is caustic and can cause severe burns. It reacts exothermically with water and releases heat. It should be kept away from moisture, acids, and oxidizers, and handled with appropriate personal protective equipment in a well-ventilated area.