Aldehydes And Ketones Result Question 45

Passage

Two aliphatic aldehydes $P$ and $Q$ react in the presence of aqueous $\mathrm{K}_2 \mathrm{CO}_3$ to give compound $R$, which upon treatment with $HCN$ provides compound $S$. On acidification and heating, $S$ gives the product shown below :

(2010)

45. The compound R is

<img src=“https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/76bab236-8795-4f49-a99d-9a5fc1db8100/public"width="400"/>

Show Answer

Answer:

Correct Answer: 45. ( a )

Solution:

The given product is an ester, obtained by condensation of a hydroxy acid obtained through hydrolysis of a cyanohydrin :

<img src=“https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/bcc8c3b7-7890-466f-2f7e-ac5c9aa77300/public"width="400">

Acid above is obtained by acid hydrolysis of cyanohydrin $S$ as

<img src=“https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/966006ec-49c2-4d55-e6f2-175152a8bc00/public"width="400">

$S$ is obtained by nucleophile addition of $HCN$ on $R$, hence $R$ is

<img src=“https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/771ca284-c776-4c05-d3e4-7676f10eae00/public"width="400">

$R$ is obtained by treatment of $P$ and $Q$ with aqueous $K _{2}CO _3$ through aldol condensation reaction as

<img src=“https://imagedelivery.net/YfdZ0yYuJi8R0IouXWrMsA/089caaaf-fdcd-48fa-f9aa-013fa9e74100/public"width="400">



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