JEE Main · 2020 · 09 Jan 2020 · Shift 1 · Aldehydes Ketones and Carboxylic Acids

Identify (A) in the following reaction sequence:

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

Answer: (B)

Solution

Under base (

NaOH

) acetone and benzaldehyde undergo a crossed aldol reaction, and on warming the

β

-hydroxy ketone loses water to give an

α, β

-unsaturated ketone. The product is benzylideneacetone,

C_{6} H_{5} CH = CHCOC H_{3}

, in which the ring is conjugated through the new double bond to the carbonyl group.

JEE Main · 2020 · 09 Jan 2020 · Shift 1 · Single correct option

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