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Question #44424

Difficulty: 8/10 | 🟢 Free

The Question

Consider the following reaction sequence on 4-(carboxymethyl)-2,6-dimethylbenzoic acid:

Step 1: $EtOH$ (excess), $H_2SO_4$ (cat.), $\Delta$ $\rightarrow$ Intermediate \textbf{X} Step 2: $BH_3 \cdot THF$ (excess), $0^\circ C$ , followed by mild $H_3O^+$ workup $\rightarrow$ Major Product \textbf{Y}

Identify the major product \textbf{Y}.

Options

A.
Ethyl 2-(4-(hydroxymethyl)-3,5-dimethylphenyl)acetate
B.
Ethyl 4-(2-hydroxyethyl)-2,6-dimethylbenzoate
C.
2-(4-(hydroxymethyl)-3,5-dimethylphenyl)ethan-1-ol
D.
4-(2-hydroxyethyl)-2,6-dimethylbenzoic 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

Esterification Steric Hindrance|Reduction Selectivity (Hydrides)|Oxidation State Traps

Why This Question Is Tricky

Common Mistakes

This problem tests the intersection of steric effects in thermodynamic processes and chemoselectivity in reductions.

The 'Hidden Variable' is the steric inhibition of the tetrahedral intermediate at the aromatic carboxylic acid, forcing the student to correctly assign regioselectivity in Step 1.

The 'Chemical Exception' trap is the counter-intuitive chemoselectivity of Borane ( $BH_3$ ), which reduces the less electrophilic carboxylic acid faster than an ester due to the initial formation of a triacyloxyborane intermediate, trapping students who rely solely on standard nucleophilic hydride ( $LiAlH_4$ / $NaBH_4$ ) reactivity trends.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Alcohols, Phenols, and Ethers - Class 12
Concept	Esterification Steric Hindrance
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free