Potassium tert-butoxide NEW

Potassium tert-butoxide is a commonly used alcohol salt with the formula (CH3)3COK. This colorless solid is a strong base commonly used in organic synthesis, and its conjugated acid tert-butanol has a pKa of about 17. In the solid state it exists as a tetrameric cuboxe-like cluster of atoms. t-BuOK is commonly used to denote potassium tert-butanol in the chemical literature.

Appearance and properties: white crystalline powder

Density: 0.910 g/mL at 20 °C

Boiling point: 275°C

Melting point: 256-258 °C (dec.)(lit.)

Flash point: 54 °F

Water solubility: REACTS

Stability: Stable, but reacts violently with water and acids, possibly leading to fire. Incompatible with water, acids,  halogenated hydrocarbons, alcohols, strong oxidizing agents, ketones, carbon dioxide.

Storage condition: Flammables area

Vapor pressure: 1 mm Hg (220 °C)

Production method

Method 1:1250 ml of dry tert-butanol is directly distilled into a reaction flask under nitrogen protection. Add 100 grams (2.6 grams of atoms) of potassium in 10 batches. The stirred mixture heats up immediately, reaching the melting point of potassium 62C within 15-60 minutes, at which point the metal disperses into dissolved droplets. As the potassium gradually dissolves, the temperature of the mixture rises to the boiling point of the tert-butanol. Adjust the stirring speed to keep the tert-butanol flowing back slightly. If the boil is too intense, stop stirring. If necessary, the reaction vessel can be immersed in a cold oil bath to cool (not a water bath). The potassium tert-butanol gradually precipitates out, and when all the potassium has reacted, the mixture becomes a thick suspension.

Method 2 is packed in a 3-liter three-neck bottle with a sealed agitator, nitrogen inlet tube (nitrogen through concentrated sulfuric acid washing bottle and anhydrous calcium chloride drying tower), 500 ml constant pressure drip funnel and reflux condenser, put in 500 ml of newly steamed tert-butanol, and add 20 grams (0.5 grams of atoms) of clean metal potassium. When the potassium reaction is complete, replace the reflux condenser with a 30 cm long fractionation column. Steam the excess of the liquor until crystals appear in the solution. Add 2 liters of dried heptane and continue the distillation until the top temperature reaches 98 ° C. The residue is dried with heptane to 1.5 L. The resulting slurry is a 1:1 complex of potassium tert-butanol and tert-butanol. Depressurize the steam bath by 20-25mm to remove the solvent. It can be stored in a nitrogen atmosphere for several months.

Use

As a strong base, it is widely used in condensation, rearrangement and ring-opening reactions in organic synthesis of chemical industry, medicine, pesticides, etc.