JEE Main · 2021 · 24 Feb 2021 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

Which of the following reagent is suitable for the preparation of the product in the above reaction?

(A)Red $P + Cl_{2}$
(B) $Ni / H_{2}$
(C) $NH_{2} - NH_{2} / C_{2} H_{5} O Θ N \oplus a$ ✓ Correct
(D) $NaBH_{4}$

Answer: (C)

Solution

The carbonyl group of the cyclohexenone has been replaced by a

C H_{2}

group while both carbon-carbon double bonds survive, so the reagent must reduce

C = O

all the way to

C H_{2}

without touching alkenes.

NaB H_{4}

stops at the secondary alcohol,

Ni/ H_{2}

would hydrogenate the ring alkene and the isopropenyl group, and red phosphorus with chlorine does not reduce carbonyl compounds at all. Hydrazine condenses with the ketone to give the hydrazone, which on heating with sodium ethoxide loses nitrogen and leaves a methylene group, the Wolff-Kishner reduction, and its basic conditions leave the alkenes untouched. The suitable reagent is hydrazine with sodium ethoxide.

JEE Main · 2021 · 24 Feb 2021 · Shift 2 · Single correct option

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JEE Main · 2021 · 24 Feb 2021 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

Solution

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