stability of acetal and hemiacetal towards acids and bases
Dear Student,
In carbonyl compounds both forward and backward reaction (reversible state) must undergo same intermediate transformation, where hemiacetal can be formed (or) decomposed under acidic (or) basic condition while protonation gives hemiacetal. The hydroxide in SN2 reaction have to be displaced for acetal, as in SN2 hydroxide removal is difficult hence the formation of acetal under basic (nucleophile) condition is not possible. But in hemiacetal basic condition favours deprotonation results in the formation of carbonyl and alcoholic compounds.
Hence Hemiacetal is stable towards both acidic and basic condition while Acetal is favoured stable under only acidic condition, an general reaction mechanism of acetal and hemiacetal is expressed below,
Regards.
In carbonyl compounds both forward and backward reaction (reversible state) must undergo same intermediate transformation, where hemiacetal can be formed (or) decomposed under acidic (or) basic condition while protonation gives hemiacetal. The hydroxide in SN2 reaction have to be displaced for acetal, as in SN2 hydroxide removal is difficult hence the formation of acetal under basic (nucleophile) condition is not possible. But in hemiacetal basic condition favours deprotonation results in the formation of carbonyl and alcoholic compounds.
Hence Hemiacetal is stable towards both acidic and basic condition while Acetal is favoured stable under only acidic condition, an general reaction mechanism of acetal and hemiacetal is expressed below,
Regards.