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The nitrogen atom in the following cycli...

The nitrogen atom in the following cyclic compounds can be removed as trimethylamine by successive Hoffmann eliminations (involving exhaustive methylation followed by heating with `AgOH`). The amine which will require a greater number of Hoffmann eliminations is:

A

B

C

D

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To solve the problem, we need to analyze the cyclic compounds given and determine which amine will require a greater number of Hoffmann eliminations to remove the nitrogen atom as trimethylamine. The process involves exhaustive methylation followed by heating with AgOH. ### Step-by-Step Solution: 1. **Identify the Compounds**: We have four cyclic amines (let's denote them as A, B, C, and D). Each compound has a nitrogen atom that can be removed through Hoffmann elimination. 2. **Understand Hoffmann Elimination**: The Hoffmann elimination process involves two main steps: - **Exhaustive Methylation**: The amine is treated with a methylating agent (like methyl iodide) to convert it into a quaternary ammonium salt. - **Heating with AgOH**: The quaternary ammonium salt is then heated with silver hydroxide, leading to the elimination of nitrogen as trimethylamine. 3. **Count the Bonds to Break**: The number of Hoffmann eliminations required is directly related to the number of bonds that need to be broken to remove the nitrogen atom: - For each bond broken, one Hoffmann elimination is required. 4. **Analyze Each Compound**: - **Compound A**: Contains 2 bonds to nitrogen. Therefore, it requires 2 Hoffmann eliminations. - **Compound B**: Contains 3 bonds to nitrogen. Therefore, it requires 3 Hoffmann eliminations. - **Compound C**: Contains 1 bond to nitrogen. Therefore, it requires 1 Hoffmann elimination. - **Compound D**: Contains 2 bonds to nitrogen. Therefore, it requires 2 Hoffmann eliminations. 5. **Determine the Maximum**: From the analysis: - Compound A: 2 eliminations - Compound B: 3 eliminations (maximum) - Compound C: 1 elimination - Compound D: 2 eliminations 6. **Conclusion**: The amine that will require a greater number of Hoffmann eliminations is **Compound B**, as it requires 3 eliminations. ### Final Answer: The amine which will require a greater number of Hoffmann eliminations is **Compound B**.
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RESONANCE ENGLISH-AROMATIC COMPOUNDS -PART-II: NATIONAL STANDARD EXAMINATION IN CHEMISTRY (NSEC) STAGE-I
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