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| ==Applications== | ==Applications== | ||
| The ''tert''-butoxide species is itself useful as a strong, non-nucleophilic base in organic chemistry.<ref name=Craine>Drury Caine “Potassium t-Butoxide” in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons, New York, 2006. {{DOI| 10.1002/047084289X.rp198.pub2}}. Article Online Posting Date: September 15, 2006</ref> It is not as strong as amide bases, e.g. ], but stronger than potassium hydroxide. Its steric bulk inhibits the group from participating in nucleophilic addition, such as in a ] or an ] reaction. Substrates that are deprotonated by potassium ''t''-butoxide include terminal acetylenes and active methylene compounds. It is useful in ] reactions. It is a strong base | The ''tert''-butoxide. hi hi hi hi species is itself useful as a strong, non-nucleophilic base in organic chemistry.<ref name=Craine>Drury Caine “Potassium t-Butoxide” in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons, New York, 2006. {{DOI| 10.1002/047084289X.rp198.pub2}}. Article Online Posting Date: September 15, 2006</ref> It is not as strong as amide bases, e.g. ], but stronger than potassium hydroxide. Its steric bulk inhibits the group from participating in nucleophilic addition, such as in a ] or an ] reaction. Substrates that are deprotonated by potassium ''t''-butoxide include terminal acetylenes and active methylene compounds. It is useful in ] reactions. It is a strong base | ||
| ==Modifications== | ==Modifications== | ||
Revision as of 23:42, 6 March 2012
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| Names | |||
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| IUPAC name potassium 2-methylpropan-2-olate | |||
| Identifiers | |||
| CAS Number | |||
| 3D model (JSmol) | |||
| ChemSpider | |||
| ECHA InfoCard | 100.011.583 
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| PubChem CID | |||
| CompTox Dashboard (EPA) | |||
InChI
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SMILES
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| Properties | |||
| Chemical formula | C4H9KO | ||
| Molar mass | 112.21196 | ||
| Appearance | solid | ||
| Melting point | 256 °C (493 °F; 529 K) | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa).
 Y verify (what is ?)
Infobox references
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Potassium tert-butoxide is the chemical compound with the formula (CH3)3COK. This colourless solid is a strong base (pKa of conjugate acid around 17) which is useful in organic synthesis. It exists as a tetrameric cubane-like cluster. It is often seen written in chemical literature as potassium t-butoxide.
Preparation
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 sensitive and older samples are often of poor quality. It is prepared by the reaction of dry tert-butanol with potassium metal. The solid is obtained by evaporating these solutions followed by heating the solid. The solid can be purified by sublimation at 220 °C and 1 mmHg.
Applications
The tert-butoxide. hi hi hi hi species is itself useful as a strong, non-nucleophilic base in organic chemistry. It is not as strong as amide bases, e.g. lithium diisopropylamide, but stronger than potassium hydroxide. Its steric bulk inhibits the group from participating in nucleophilic addition, such as in a Williamson ether synthesis or an SN2 reaction. Substrates that are deprotonated by potassium t-butoxide include terminal acetylenes and active methylene compounds. It is useful in dehydrohalogenation reactions. It is a strong base
Modifications
Many modifications have been reported that influence the reactivity of this reagent. The compound adopts a complex cluster structure (the picture to the right 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, enhancing the basicity of the butoxide. Schlosser's base, a mixture of the alkoxide and an alkyl lithium compound, is a related but stronger base.
References
- William S. Johnson and William P. Schneider (1963). "β-Carbethoxy-γ,γ-diphenylvinylacetic acid". Organic Syntheses; Collected Volumes, vol. 4, p. 132.
- ^ Drury Caine “Potassium t-Butoxide” in Encyclopedia of Reagents for Organic Synthesis John Wiley & Sons, New York, 2006. doi:10.1002/047084289X.rp198.pub2. Article Online Posting Date: September 15, 2006