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Question #44480
The Question
An organic compound \textbf{X} () is synthesized by the reaction of benzene with an excess of 2-chloro-2-methylpropane in the presence of anhydrous at 298 K. Compound \textbf{X} is subsequently subjected to Friedel-Crafts acylation using 1 equivalent of acetyl chloride () and anhydrous in at 298 K, followed by aqueous workup, to yield compound \textbf{Y} as the major organic product. Which of the following represents the correct IUPAC name of compound \textbf{Y}?
Options
- A.
1-(2,5-di-\textit{tert}-butylphenyl)ethan-1-one
- B.
1-(4-\textit{tert}-butylphenyl)ethan-1-one
- C.
1-(3,5-di-\textit{tert}-butylphenyl)ethan-1-one
- D.
1-(2,4-di-\textit{tert}-butylphenyl)ethan-1-one
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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
Friedel-Crafts Alkylation Limitations|Steric Hindrance in SN2|Hybridization and Geometry
Why This Question Is Tricky
Common Mistakes
The problem tests the boundary conditions of Electrophilic Aromatic Substitution (EAS) under extreme steric constraints.
Students typically apply the rule that alkyl groups are activating and \textit{ortho}/\textit{para} directing, leading them to predict substitution at the remaining open positions (Option A).
The 'Chemical Exception' is \textit{ipso}-substitution.
When steric hindrance at the \textit{ortho} position is insurmountable, electrophilic attack redirects to the substituted \textit{ipso}-carbon.
Because the \textit{tert}-butyl group can leave as a stable carbocation, dealkylation occurs, yielding an unexpected mono-alkylated acetophenone derivative.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Hydrocarbons - Class 11 Part 2 |
| Concept | Friedel-Crafts Alkylation Limitations |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |