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Question #99833
The Question
An unknown mono-substituted aniline derivative features a bulky substituent at the ortho position. High-resolution mass spectrometry (HRMS) determines the exact molar mass of to be . (Use precise atomic masses: ). Given that the of unsubstituted aniline is at , which of the following is the most chemically accurate value for , considering the dominant electronic and steric effects?
Options
- A.
10.22
- B.
8.80
- C.
7.44
- D.
11.85
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
Precision in Atomic Mass Units|Ortho-Effect in Anilines|Basicity-Solvation Competition
Why This Question Is Tricky
Examiner Levers
Extraneous Data
Provides unnecessary variables (Red Herrings) to test conceptual focus.
Difficulty Boost : +3Logical Assertion
Tests the causal relationship between two true statements.
Difficulty Boost : +4Common Mistakes
The question tests the 'Ortho-Effect' in substituted anilines, specifically the 'Basicity-Solvation Competition'.
Students often mistakenly assume that the +I effect of the tert-butyl group will increase basicity (leading to the trap answer 8.80).
The hidden variable is the steric hindrance to solvation of the anilinium ion, which overrides the inductive effect and decreases basicity.
Additionally, the problem demands precision in atomic mass units; using rounded masses allows for the incorrect formula \ce{C9H11NO} (e.g., 2-propionylaniline), which would lead to the trap answer 11.85 due to the strong -M effect.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Some Basic Concepts of Chemistry - Class 11 Part 1 |
| Concept | Precision in Atomic Mass Units |
| Difficulty | 8 |
| Cognitive Load | 8 |
| Target Solve Time | 180 sec |
| Access | Free |