Question

The reaction of 2,4-dinitrofluorobenzene with hydrazine produces a yellow orange solid X used for the identification of an organic functional group G. X and G, respectively, are

• A.
• B.

  

• C.

  

• D.

  

Answer 1

The Correct Option is B

To solve this question, we need to determine the products of the reaction between 2,4-dinitrofluorobenzene and hydrazine.

Step 1: Understanding the Reaction

2,4-dinitrofluorobenzene is a compound with strong electron-withdrawing nitro groups at the 2 and 4 positions on a benzene ring, which activates the fluorine for nucleophilic substitution.

Upon reaction with hydrazine (NH₂NH₂), the nucleophilic nitrogen on the hydrazine attacks the carbon with the fluorine, displacing the fluoride ion. This reaction is characteristic and leads to the formation of a hydrazone linkage.

Step 2: Identifying the Yellow Orange Solid X

The product of this reaction is known to be a 2,4-dinitrophenylhydrazone, a yellow-orange solid. This compound, referred to as X in the question, is known for its intense coloration, which is used in chemical analysis.

Step 3: Determining the Functional Group G

The functional group that 2,4-dinitrophenylhydrazone helps identify is the carbonyl group (C=O), commonly found in aldehydes and ketones. This is because hydrazone derivatives form selectively when carbonyl compounds react with hydrazine derivatives.

In the context of this reaction, hydrazines are typical reagents for testing carbonyl functionalities, and the formation of 2,4-dinitrophenylhydrazone derivatives confirms the presence of such a group.

Conclusion

Thus, the compounds X and G are identified as 2,4-dinitrophenylhydrazone and carbonyl group, respectively.