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Question #44408
The Question
Consider the acid-catalyzed rearrangement of \ce{2,2-dimethyl-1-phenylpropane-1,3-diol} under heating with catalytic \ce{H2SO4}. Assuming the reaction is driven by thermodynamic control to its most stable final product, identify the major organic product formed.
Options
- A.
2-methyl-3-phenylbutanal
- B.
2-methyl-3-phenylbut-2-en-1-ol
- C.
2,2-dimethyl-3-phenylpropanal
- D.
3-methyl-4-phenylbutan-2-one
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
Pinacol-Pinacolone Rearrangement|SN1 Carbocation Rearrangement
Why This Question Is Tricky
Common Mistakes
This question tests the student's ability to recognize a cascade rearrangement that extends beyond a standard single-shift Pinacol rearrangement.
The primary trap lies in stopping at the first rearranged tertiary carbocation and predicting an elimination product (Option B), or incorrectly assuming the primary alcohol leaves first to directly form an aldehyde (Option C).
The true pathway requires understanding that the global thermodynamic sink—the formation of the C=O bond via an oxocarbocation—drives a multi-step sequence of a 1,2-alkyl shift followed by a 1,2-hydride shift.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Alcohols, Phenols, and Ethers - Class 12 |
| Concept | Pinacol-Pinacolone Rearrangement |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |