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MHTCET 26 Apr 2025 Shift 2 Paper

Question : 93 of 150

Marks: +1, -0

Which of the following is a Fittig reaction?

$C_{6} \mathrm{H}_{5} \mathrm{Br}+\mathrm{CH}_{3}-\mathrm{Br}+2 \mathrm{Na} \xrightarrow[\text { ether }]{\text { dry }} C_{6} \mathrm{H}_{5}-\mathrm{CH}_{3}+2 \mathrm{NaBr}$
$2 C_{2} \mathrm{H}_{5} \mathrm{Br}+2 \mathrm{Na} \xrightarrow[\text { ether }]{\mathrm{dr}} C_{2} \mathrm{H}_{5}-C_{2} \mathrm{H}_{5}+2 \mathrm{NaBr}$
$2 \mathrm{CH}_{3} \mathrm{Br}+2 \mathrm{Na} \xrightarrow[\text { ether }]{\text { dry }} \mathrm{CH}_{3}-\mathrm{CH}_{3}+2 \mathrm{NaBr}$
$2 C_{6} \mathrm{H}_{5} \mathrm{Br}+2 \mathrm{Na} \xrightarrow[\text { ether }]{\text { dry }} C_{6} \mathrm{H}_{5}-C_{6} \mathrm{H}_{5}+2 \mathrm{NaBr}$

Solution:

Concept:

The Fittig reaction is the coupling of two aryl halides with sodium metal in dry ether to form a biaryl compound.

Explanation:

Recall the three related reactions.

The Wurtz reaction couples two alkyl halides:

2 R-X+2 \mathrm{Na} \xrightarrow[\text { dry ether }]{\text { }} R-R+2 \mathrm{NaX}

The Wurtz-Fittig reaction couples one aryl halide with one alkyl halide:

\mathrm{Ar}-X+R-X+2 \mathrm{Na} \xrightarrow[\text { dry ether }]{\text { }} \mathrm{Ar}-R+2 \mathrm{NaX}

The Fittig reaction couples two aryl halides:

2 \mathrm{Ar}-X+2 \mathrm{Na} \xrightarrow[\text { dry ether }]{\text { }} \mathrm{Ar}-\mathrm{Ar}+2 \mathrm{NaX}

Now check each option.

Option A mixes bromobenzene and bromomethane, giving toluene; this is a Wurtz-Fittig reaction.

Option B couples two ethyl bromides, giving butane; this is a Wurtz reaction.

Option C couples two methyl bromides, giving ethane; this is also a Wurtz reaction.

Option D couples two bromobenzene molecules, giving biphenyl (

\mathrm{C}_6\mathrm{H}_5-\mathrm{C}_6\mathrm{H}_5

This matches the aryl-aryl coupling of the Fittig reaction.

Answer:

Option D is the Fittig reaction.

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