Answer: Nucleophilicity is a kinetic property (rate of attack on carbon); basicity is a thermodynamic property (affinity for proton); a good base is not necessarily a good nucleophile.
- A Nucleophilicity is a kinetic property (rate of attack on carbon); basicity is a thermodynamic property (affinity for proton); a good base is not necessarily a good nucleophile
- B Nucleophilicity and basicity are in fact fundamentally the very same underlying property, just measured using different units in general practice as frequently described
- C Strong Bronsted bases are said to rarely simultaneously be capable of acting as effective nucleophiles in any solvent in most textbook accounts during normal conditions as generally observed
- D The iodide ion is actually said to be a noticeably stronger Bronsted base toward a proton than the fluoride ion is in typical laboratory settings under usual circumstances
Correct answer: A. Nucleophilicity is a kinetic property (rate of attack on carbon); basicity is a thermodynamic property (affinity for proton); a good base is not necessarily a good nucleophile
Explanation: These are related but distinct properties. I⁻ is a better nucleophile than F⁻ (more polarisable, less solvated) but F⁻ is a stronger base (higher pKa of HF). Bulky bases like t-BuO⁻ are strong bases but poor nucleophiles.
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.