Alkoxide
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An alkoxide is the conjugate base of an alcohol, and therefore has an organic group bonded to a negatively charged oxygen atom. They can be written as R-O–, where R is a saturated organic substituent. Alkoxides are both strong bases and good nucleophiles (unless R is very bulky, creating steric hindrance). Alkoxides, though generally not stable in protic solvents such as water, are found as intermediaries in various reactions, including the Williamson ether synthesis reaction for forming ethers.
An enolate is formally an 1,2-unsaturated alkoxide, but has substially different behavior, and is usually produced by α-deprotonation of a carbonyl compound such as ketone or aldehyde.
Alkoxides can be produced by dissolving reactive metal, e.g. metallic sodium, into an alcohol. The alcohol acts as an acid, and hydrogen is produced:
- R-OH + Na → R-O–Na+ + ½H2
Hydroxide is not a strong enough base to stoichiometrically deprotonate an alcohol. Alkoxides cannot exist but in trace amounts in water solutions due the acidity of water. Therefore, quantitative amounts of alkoxides must be dissolved in less acidic solvents, such as ethers.
Strongly basic organometallics such as organolithiums can also deprotonate an alcohol. Alkoxides can be used as bases to deprotonate ketones at the alpha position to produce enolates.et:Alkoholaadid ja:アルコキシド
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