Given below are two statements: Statement - I: High concentration of strong nucleophilic reagent with secondary alkyl halides which do not have bulky substituents will follow S_N ^2 mechanism. Statement - II: A secondary alkyl halide when treated with a large excess of ethanol follows S_N ^1 mechanism. In the light of the above statements, choose the most appropriate from the options given below:

Both Statement I and Statement II are true.

Statement I is true but Statement II is false.

Both Statement I and Statement II are false.

Statement I is false but Statement II is true.

Haloalkanes and Haloarenes PYQ — JEE Main 2024 · 30 Jan · Shift 2 · Q10 with Solution

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Correct answer: A

Analyze Statement I
Statement I says: High concentration of strong nucleophilic reagent with secondary alkyl halides which do not have bulky substituents will follow $\mathrm{S_N2}$ mechanism.
- $\mathrm{S_N2}$ $S_{N} 2$ is favored by:
  - strong nucleophile
  - high nucleophile concentration
  - less steric hindrance
- For secondary alkyl halides, both $\mathrm{S_N1}$ and $\mathrm{S_N2}$ are possible, but if the substrate is not bulky and the nucleophile is strong and concentrated, backside attack becomes feasible.
Therefore, Statement I is true.
Analyze Statement II
Statement II says: A secondary alkyl halide when treated with a large excess of ethanol follows $\mathrm{S_N1}$ mechanism.
- Ethanol is:
  - a weak nucleophile
  - a polar protic solvent
- Polar protic solvents stabilize the carbocation and the leaving group, thus favoring ionization.
- With secondary alkyl halides, in such conditions, the reaction tends toward $\mathrm{S_N1}$ solvolysis.
Therefore, Statement II is also true.
Choose the correct option
Since both statements are true, the correct option is: $\boxed{\text{A}}$
Compare with stored correct answer
Stored correct answer: A
Derived answer: A
Hence, they agree.

View written solutionFree

Correct answer: A

Analyze Statement I
Statement I says: High concentration of strong nucleophilic reagent with secondary alkyl halides which do not have bulky substituents will follow $\mathrm{S_N2}$ mechanism.
- $\mathrm{S_N2}$ $S_{N} 2$ is favored by:
  - strong nucleophile
  - high nucleophile concentration
  - less steric hindrance
- For secondary alkyl halides, both $\mathrm{S_N1}$ and $\mathrm{S_N2}$ are possible, but if the substrate is not bulky and the nucleophile is strong and concentrated, backside attack becomes feasible.
Therefore, Statement I is true.
Analyze Statement II
Statement II says: A secondary alkyl halide when treated with a large excess of ethanol follows $\mathrm{S_N1}$ mechanism.
- Ethanol is:
  - a weak nucleophile
  - a polar protic solvent
- Polar protic solvents stabilize the carbocation and the leaving group, thus favoring ionization.
- With secondary alkyl halides, in such conditions, the reaction tends toward $\mathrm{S_N1}$ solvolysis.
Therefore, Statement II is also true.
Choose the correct option
Since both statements are true, the correct option is: $\boxed{\text{A}}$
Compare with stored correct answer
Stored correct answer: A
Derived answer: A
Hence, they agree.