Answer: Rate is slower in polar protic solvent because the nucleophile is heavily solvated and less reactive.
- A Rate is much faster in polar protic solvent because the leaving group is destabilised instead
- B Rate is slower in polar protic solvent because the nucleophile is heavily solvated and less reactive
- C The rate stays exactly identical regardless of which solvent type is chosen
- D Polar protic solvent always forces the mechanism to switch completely from SN2 to SN1
Correct answer: B. Rate is slower in polar protic solvent because the nucleophile is heavily solvated and less reactive
Explanation: In polar protic solvents, the nucleophile forms strong hydrogen bonds with the solvent, reducing its reactivity. SN2 reactions are much faster in polar aprotic solvents (DMF, DMSO, acetone) where the nucleophile is free.
SN2 proceeds in a single step with backside attack and inversion of configuration, while SN1 forms a planar carbocation intermediate first, leading to racemisation.
Concept context
Study carbon-halogen compounds: how they are made, how they react via SN1/SN2 and elimination, their stereochemistry, and their environmental impact.