JEE Main · 2008 · 27 Apr 2008 · Offline · Hydrocarbons

The hydrocarbon which can react with sodium in liquid ammonia is

(A) $CH_{3} CH_{2} CH_{2} C \equiv CCH_{2} CH_{2} CH_{3}$
(B) $CH_{3} CH_{2} C \equiv CH$ ✓ Correct
(C) $CH_{3} CH = CHCH_{3}$
(D) $CH_{3} CH_{2} C \equiv CCH_{2} CH_{3}$

Answer: (B)

Solution

Sodium in liquid ammonia reacts with the acidic hydrogen of a terminal alkyne to give the sodium acetylide, so the hydrocarbon that responds is the one with a hydrogen on a triple-bonded carbon. Of the choices only

C H_{3} C H_{2} C \equiv CH

is a terminal alkyne; the internal alkynes and the alkene have no comparably acidic hydrogen, so it is this terminal alkyne that reacts.

JEE Main · 2008 · 27 Apr 2008 · Offline · Single correct option

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