Propose a mechanism to account for the formation of a cyclic acetal from 4-hydroxypentanal and one equivalent of methanol. If th
e carbonyl oxygen of 4-hydroxypentanal is enriched with oxygen-18, do you predict that the oxygen label appears in the cyclic acetal or in the water
1 answer:
Answer:
If carbonyl oxygen of 4-hydroxypentanal is enriched with , then the oxygen label appears in the water .
Explanation:
- In the first step, -OH group at C-4 gives intramolecular nucleophilic addition reaction at carbonyl center to produce a cyclic hemiacetal.
- Then, one equivalent of methanol gives nucleophilic substitiution reaction by substituting -OH group in cyclic hemiacetal to produce cyclic acetal.
- If carbonyl oxygen of 4-hydroxypentanal is enriched with
, then the oxygen label appears in the water produced at the end of reaction.
- Full reaction mechanism has been shown below.
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<h2>Acetic Acid + Sodium ethoxide ⇄ Butyric Acid + Sodium Hydroxide</h2>
Explanation:
An ionic equation for the reaction of acetic acid with sodium ethoxide is as follows -
- Reactants -
Acetic Acid and Sodium ethanolate (sodium ethoxide)
- Products -
Butyric Acid and Sodium hydroxide
Hence,
Acetic Acid + Sodium ethoxide ⇄ Butyric Acid + Sodium Hydroxide
⇄
- Weak acids and bases have low energy than strong acids and bases.
- The chemical equilibria shift the reaction side with the species having lower energy.
- Given reaction is an acid-base reaction in which the equilibrium favors the starting material that means it will go to the side of the weakest acid that is acetic acid is weaker than butyric acid.