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Question #44370

Difficulty: 8/10 | 🟢 Free

The Question

Consider the acid-catalyzed hydration of 2-(1,1-dimethylethyl)-3,3-dimethylbut-1-ene using dilute aqueous $\ce{H2SO4}$ at 298 K. The reaction yields a major product $P$ . Which of the following represents the correct IUPAC name of $P$ and the primary kinetic/thermodynamic driving force for its formation?

Options

A.
2,2,3,4,4-pentamethylpentan-3-ol; The intermediate is a highly stable tertiary carbocation which undergoes rapid nucleophilic trapping.
B.
2,3,3,4,4-pentamethylpentan-2-ol; A 1,2-methyl shift relieves severe steric B-strain in the transition state of the nucleophilic addition.
C.
2-tert-butyl-2,3,3-trimethylbutan-1-ol; A 1,2-hydride shift occurs to place the positive charge on a less sterically hindered primary carbon.
D.
3,3,4,4-tetramethylpentan-2-ol; The intermediate undergoes $\beta$ -fragmentation to relieve steric strain, followed by hydration.

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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

Acid-Catalyzed Hydration Mechanism|Nucleophilic Addition Sterics

Why This Question Is Tricky

Common Mistakes

This question tests a critical 'Chemical Exception' where students blindly apply the rule that 'tertiary carbocations do not rearrange unless they can form a resonance-stabilized cation.' Here, both the initial and rearranged carbocations are tertiary.

The hidden variable is the extreme steric hindrance (B-strain) in the transition state for nucleophilic attack on the 1,1-di-tert-butylethyl cation.

The 1,2-methyl shift is driven by the kinetic necessity to create a less hindered electrophilic center, forcing an analysis of the collision geometry rather than just intermediate stability.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Alcohols, Phenols, and Ethers - Class 12
Concept	Acid-Catalyzed Hydration Mechanism
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free