Potassium tert-butoxide

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Potassium tert-butoxide
Names
IUPAC name
Potassium 2-methylpropan-2-olate
Other names
Potassium t-butoxide
Potassium tert-butoxide
Potassium tert-butylate
Properties
C4H9OK
Molar mass 112.21 g/mol
Appearance Colorless to slight yellow solid
Odor Odorless
Melting point 256–258 °C (493–496 °F; 529–531 K) (decomposes)
Boiling point Sublimation begins from 220 °C (428 °F; 493 K) (at 1 mmHg)
Hydrolyzes
Solubility Reacts with acids, carboxylic acids, halocarbons
Soluble in tert-butanol, THF
Slightly soluble in diethyl ether, toluene
Poorly soluble in hexane
Solubility in diethyl ether 4.34 g/100 g (25 °C)
Solubility in hexane 0.27 g/100 g (25 °C)
Solubility in tert-Butanol 17.8 g/100 g (25 °C)
Solubility in tetrahydrofuran 25 g/100 g (25 °C)
Solubility in toluene 2.27 g/100 g (25 °C)
Hazards
Safety data sheet Sigma-Aldrich
Lethal dose or concentration (LD, LC):
690 mg/kg (rat, oral)
Related compounds
Related compounds
tert-Butanol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Potassium tert-butoxide is the chemical compound with the formula C4H9OK, sometimes written as (CH3)3COK+. It is a strong base (pKa of conjugate acid around 17), very useful in organic reactions.

Properties

Chemical

Potassium tert-butoxide will readily hydrolyze in water to form tert-butanol and potassium hydroxide.

(CH3)3COK + H2O → (CH3)3C-OH + KOH

Potassium tert-butoxide reacts exothermically with chloroform.

Physical

Potassium t-butoxide is a colorless solid, which hydrolyzes in water, but has good solubility in organic solvents, like tert-butanol, THF.[1]

Availability

Potassium tert-butoxide is sold by many chemical suppliers.

Preparation

Potassium t-butoxide can be made by carefully adding metallic potassium to tert-butanol.

(CH3)3C-OH + K → (CH3)3COK+ + ½ H2

Purification can be done via sublimation under vacuum.

Projects

  • Preparation of metallic potassium
  • Strong non-nucleophilic base in organic reactions
  • Ignition in contact with chloroform (or dichloromethane)

Handling

Safety

Potassium tert-butoxide is sensitive to water and is corrosive. Wear proper protection when handling the compound.

Storage

Potassium tert-butoxide should be kept in dry air-tight containers, like Schlenk flasks or desiccators.

Disposal

Can be neutralized by adding it in plenty of water, then poured down the drain.

References

  1. http://onlinelibrary.wiley.com/doi/10.1002/047084289X.rp198.pub2/abstract

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