JEE Main20238 Apr 2023Morning ShiftChemistryHaloalkanes and HaloarenesActual
Choose the halogen which is most reactive towards SN1 reaction in the given compounds (A, B, C & D) A. B. C. D.
Options
- AA - Br ( b ) ; B - I ( a ) ; C - Br ( a ) ; D - Br ( a )
- BA - Br ( b ) ; B - I ( b ) ; C - Br ( b ) ; D - Br ( b )
- CA - Br ( a ) ; B - I ( a ) ; C - Br ( b ) ; D - Br ( a )
- DA - Br ( a ) ; B - I ( a ) ; C - Br ( a ) ; D - Br ( a )
Correct answer
C. A - Br ( a ) ; B - I ( a ) ; C - Br ( b ) ; D - Br ( a )
Step-by-step solution
The leaving group which results in the formation of more stable carbocation will be more reactive towards S N 1 reaction. In the above molecule, by leaving of Br ( a ) benzyl carbocation is formed. Benzyl carbocation is more stable than aliphatic carbocation. By replacing I ( a ) in the above molecule, allyl carbocation is formed. Allyl carbocation is more stable than aliphatic carbocation. In the above molecule, it is difficult to replace Br ( a ) , as carbocation formed at bridge head position is very difficult.