14. For the depicted transformation, which structure represents the intermediate
ID: 1039960 • Letter: 1
Question
14. For the depicted transformation, which structure represents the intermediate after the first step in the reaction (immediately before oxygen-carbon bond formation)? (1) cat. H,SO, ?? ?? Dean-Stark trap MeO ?? BH 1 15. or the reaction in #14 (note that the reaction given is not balanced), the reaction would work best by: (1) a) Running the reaction on ice b) Running the reaction at 110 °C c) Adding water d) Adding base instead of acid | 16. One of the mechanistic steps in the reaction in #14 is: (1) MeO Meo HO OH Me Meo MeO
Explanation / Answer
14) Option A:
=O in -COOH moiety, is in resonance with -OH of the same moitey, and being more electronegative, Intermediate A is more likely to be formed and more stable.
15) Option B:
Use of Dean stark apparatus is to collect water, as their is removalof water due to the condensation reaction, if you keep the reaction at 110 degree celsius, water will be evaporated from the reaction mixture and collected in dean-stark apparatus, hence according to le-chatelier's principle, reaction will proceed in a forward direction, as intended.
16) Option D:
As the intermediate formed in Q.14, is resonance stabilised, the dissociation (removal) of water will proceed accordingly.
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