Chemistry Alkyl Halides UHS 2024
PMDC Verified Question 3 of 13
Alkyl halides involving -C-X bond breakage and -C-Nu bond formation simultaneously would follow which one of the following mechanisms:
A
\( S_N1 \)
B
\( E_1 \)
C
\( S_N2 \)
D
\( E_2 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: \( S_N2 \)
Concept:

A concerted mechanism occurs when all bond-breaking and bond-forming steps happen in a single coordinated motion without forming an intermediate.

Solution:

  • The term "simultaneously" indicates a one-step reaction passing through a single transition state.
  • Because it specifies the formation of a Carbon-Nucleophile (-C-Nu) bond, this is a substitution reaction, not an elimination.
  • The single-step, concerted substitution mechanism is \( S_N2 \) (Substitution Nucleophilic Bimolecular).


Why other options are incorrect:

  • Option A: \( S_N1 \) is step-wise (breakage first, formation second).
  • Options B & D: \( E_1 \) and \( E_2 \) are elimination reactions that form pi bonds, not C-Nu substitution bonds.

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