At equilibrium, compound B predominates because it is more stable than A. A ketonecarbonyl is more stabilized than an aldehyde, and the carbonyl in B is conjugated with thebenzene ring.(b)The isolated product is the double hemiacetal formed between two molecules of compound A.18.35(a)The only stereogenic center in piperitone is adjacent to a carbonyl group. Base-catalyzed enol-ization causes this carbon to lose its stereochemical integrity.Both the enolate and enol of piperitone are achiral and can revert only to a racemic mixture ofpiperitones.(b)The enol formed from menthone can revert to either menthone or isomenthone.Only the stereochemistry at thea-carbon atom is affected by enolization. The other stereogeniccenter in menthone (the one bearing the methyl group) is not affected.
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