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Question #45073

Difficulty: 8/10 | 🟢 Free

The Question

Consider the following reaction sequence:

$\ce{2-Bromo-2,4-dimethylpentane + t-BuOK ->[\Delta, t-BuOH] A (Major)}$ $\ce{A + O3 ->[Zn/H2O] B + C}$

Compound \textbf{B} gives a positive iodoform test but a negative Tollens' test. Compound \textbf{C} gives a positive Tollens' test but a negative iodoform test.

$\ce{B + I2 + NaOH -> \text{Yellow precipitate} + D (Salt)}$ $\ce{D + H3O+ -> E}$

Identify the IUPAC name of compound \textbf{E}.

Options

A.
3-Methylbutanoic acid
B.
Ethanoic acid
C.
2-Methylpropanoic acid
D.
2,2-Dimethylpropanoic acid

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Mechanism_Trap

Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.

Concepts Behind This Question

Electrophile vs Nucleophile|E2 Regioselectivity (Saytzeff vs Hoffmann)|Haloalkanes and Haloarenes

Why This Question Is Tricky

Common Mistakes

This question tests the steric control of regioselectivity in E2 eliminations (Hofmann vs.

Zaitsev rule).

Students often blindly apply Zaitsev's rule to form the most substituted alkene.

The 'Trap' is that the bulky base (Potassium tert-butoxide) forces the formation of the less substituted Hofmann product.

The problem elegantly masks this trap by ensuring that BOTH the Zaitsev and Hofmann pathways yield ozonolysis fragments that perfectly satisfy the given qualitative tests (one giving a positive iodoform test, the other a positive Tollens' test).

This prevents the student from working backwards from the qualitative tests to correct their initial mechanistic error.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Organic Chemistry – Some Basic Principles and Techniques - Class 11 Part 2
Concept	Electrophile vs Nucleophile
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free