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Question #43976
The Question
An optically active haloalkane, (S)-2-chloro-1,1,1-trifluoropropane (\textbf{X}), is treated with an excess of diethylamine (\ce{Et2NH}) in methanol at 330 K in a sealed tube to yield a major organic product \textbf{Y}. Subsequently, \textbf{Y} is reacted with \ce{Cl2(aq)} in the presence of excess \ce{H2O(l)} to produce the major product \textbf{Z}. Identify the structure and IUPAC name of \textbf{Z}.
Options
- A.
2-chloro-3,3,3-trifluoropropan-1-ol, \ce{CF3-CHCl-CH2OH}
- B.
1-chloro-3,3,3-trifluoropropan-2-ol, \ce{CF3-CH(OH)-CH2Cl}
- C.
1,2-dichloro-3,3,3-trifluoropropane, \ce{CF3-CHCl-CH2Cl}
- D.
(R)-N,N-diethyl-1,1,1-trifluoropropan-2-amine, \ce{CF3-CH(NEt2)-CH3}
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Exception_Exposure
Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.
Concepts Behind This Question
DDT and Freon Chemistry|Basicity-Solvation Competition|Ammonolysis Complexity
Why This Question Is Tricky
Common Mistakes
This problem tests two critical exceptions to standard textbook rules.
First, it exploits the 'Basicity-Solvation Competition'.
Students often blindly predict an SN2 inversion for secondary halides reacting with amines (hence the (R)-enantiomer trap).
However, they fail to account for the protic solvent (methanol) caging the nucleophile and the CF3 group acidifying the beta-protons, which shifts the mechanism entirely to E2.
Second, it tests the 'Reversed Regioselectivity' in halohydrin formation.
While standard Markovnikov rules dictate nucleophilic attack at the more substituted carbon of the halonium intermediate, the extreme inductive (-I) effect of the CF3 group destabilizes the partial positive charge at C2, forcing the water molecule to attack the terminal C3 position instead.
Quick Facts About This Question
Question Information
| Subject | Chemistry |
| Chapter | Haloalkanes and Haloarenes - Class 12 |
| Concept | DDT and Freon Chemistry |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |