Which one of the following methods is neither meant for the synthesis nor for separation of amines?

Compounds Containing Nitrogen PYQ — JEE Main 2005 · Shift 0 · Q21 with Solution

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Correct answer: C

Understand what is being asked

We need the method which is neither used for:

synthesis of amines, nor
separation of amines.

So we check each option one by one.

Option A: Hinsberg method

The Hinsberg method is used to distinguish and separate primary, secondary, and tertiary amines using benzenesulphonyl chloride.

So, it is definitely a method for separation of amines.

Hence, A is not the answer.

Option B: Hofmann method

In the context of amines, the Hofmann bromamide degradation converts an amide into a primary amine having one carbon less:

RCONH_2 \xrightarrow{Br_2/KOH} RNH_2

Thus, it is a method for synthesis of amines.

Hence, B is not the answer.

Option C: Wurtz reaction

The Wurtz reaction is used to prepare alkanes by coupling alkyl halides with sodium in dry ether:

2R-X + 2Na \rightarrow R-R + 2NaX

This reaction is not used for synthesis of amines and also not used for separation of amines.

Hence, C fits the requirement.

Option D: Curtius reaction

The Curtius reaction/rearrangement converts an acyl azide into an isocyanate, which on hydrolysis gives a primary amine:

RCON_3 \rightarrow R-NCO \rightarrow RNH_2

So, it is a method for synthesis of amines.

Hence, D is not the answer.

Final conclusion

Hinsberg method $\rightarrow$ separation of amines
Hofmann method $\rightarrow$ synthesis of amines
Wurtz reaction $\rightarrow$ preparation of alkanes, not amines
Curtius reaction $\rightarrow$ synthesis of amines

Therefore, the method which is neither meant for synthesis nor for separation of amines is:

\boxed{\text{C: Wurtz reaction}}

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View written solutionFree

Correct answer: C

Understand what is being asked

We need the method which is neither used for:

synthesis of amines, nor
separation of amines.

So we check each option one by one.

Option A: Hinsberg method

The Hinsberg method is used to distinguish and separate primary, secondary, and tertiary amines using benzenesulphonyl chloride.

So, it is definitely a method for separation of amines.

Hence, A is not the answer.

Option B: Hofmann method

In the context of amines, the Hofmann bromamide degradation converts an amide into a primary amine having one carbon less:

RCONH_2 \xrightarrow{Br_2/KOH} RNH_2

Thus, it is a method for synthesis of amines.

Hence, B is not the answer.

Option C: Wurtz reaction

The Wurtz reaction is used to prepare alkanes by coupling alkyl halides with sodium in dry ether:

2R-X + 2Na \rightarrow R-R + 2NaX

This reaction is not used for synthesis of amines and also not used for separation of amines.

Hence, C fits the requirement.

Option D: Curtius reaction

The Curtius reaction/rearrangement converts an acyl azide into an isocyanate, which on hydrolysis gives a primary amine:

RCON_3 \rightarrow R-NCO \rightarrow RNH_2

So, it is a method for synthesis of amines.

Hence, D is not the answer.

Final conclusion

Hinsberg method $\rightarrow$ separation of amines
Hofmann method $\rightarrow$ synthesis of amines
Wurtz reaction $\rightarrow$ preparation of alkanes, not amines
Curtius reaction $\rightarrow$ synthesis of amines

Therefore, the method which is neither meant for synthesis nor for separation of amines is:

\boxed{\text{C: Wurtz reaction}}

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Compounds Containing Nitrogen question

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