JEE Main · 2019 · 12 Jan 2019 · Shift 1 · Aldehydes Ketones and Carboxylic Acids

In the following reactions, products A and B are:

(A)(see structures)
(B)(see structure)
(C)(see structure)
✓ Correct
(D)(see structure)

Answer: (C)

Solution

The sequence is a base-promoted aldol reaction followed by acid work-up and heating. The first step joins the two carbonyl partners to give the

β

-hydroxy carbonyl compound as product

A

. On warming with acid this

β

-hydroxy carbonyl loses water, and because the new double bond falls into conjugation with the carbonyl the dehydration is favourable; the resulting

α, β

-unsaturated carbonyl compound is product

B

. These are the structures shown.

JEE Main · 2019 · 12 Jan 2019 · Shift 1 · Single correct option

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