Fundamentals of Organic ChemistryChemistryHaloalkanes and Haloarenes
Which of the given reactions are likely to proceed predominantly via an S _ N 1 mechanism? (i) (ii) (iii) (iv)
Options
- A(i) and (iv)
- B(iii) and (iv)
- C(ii) and (iii)
- D(ii), (iii), and (iv)
Correct answer
B. (iii) and (iv)
Step-by-step solution
To determine which reactions proceed predominantly via an S _ N 1 mechanism, we need to analyze the substrate (alkyl halide) and the reaction conditions (solvent and nucleophile) for each case. 1. Reaction (i): The reactant is (chloromethyl)cyclohexane, which is a primary alkyl halide. The reagents are NaI in acetone. Acetone is a polar aprotic solvent, which strongly favors the S _ N 2 mechanism. Primary halides do not form stable carbocations and thus do not undergo S _ N 1 reactions. Therefore, this reaction pro