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Question #44369
The Question
Consider the acid-catalyzed hydration of an optically pure sample of (3S)-3-methylhex-1-ene using dilute at 298 K. Considering only the alcohol products formed, let be the total number of fractions obtained upon careful fractional distillation of the product mixture. Let be the number of these fractions that are optically active. What is the value of ?
Options
- A.
6
- B.
4
- C.
9
- D.
2
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
Acid-Catalyzed Hydration Mechanism|Optical Activity and Enantiomers
Why This Question Is Tricky
Common Mistakes
The question tests the boundary between concerted mechanisms and stepwise carbocation rearrangements.
A common trap is assuming that reactions involving chiral starting materials will always yield optically active products (chiral induction).
Students often fail to recognize that a 1,2-hydride shift from a chiral center converts it into a planar, sp2-hybridized carbocation.
Because this intermediate is achiral, the subsequent nucleophilic attack is not stereoselective, resulting in a racemic (optically inactive) mixture for the major product.
Furthermore, it tests the physical property differences between enantiomers (same boiling point, 1 fraction) and diastereomers (different boiling points, multiple fractions).
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 |