Question

35 multiple answer 2 points
which of the following statements describe a favorable attribute of a leaving group? (more than one answer is possible.)
□ the departed leaving group should have low basicity.
□ good leaving groups need to have low steric hindrance.
□ the lower the electronegativity of the leaving group the better.
□ the leaving group should be highly polarizable.
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Explanation:

• For A: A leaving group with low basicity is more stable after leaving. Weak bases are better leaving groups as they can more easily accept the electron pair during the reaction.
• For D: A highly polarizable leaving group can more easily accommodate the negative charge that develops as it leaves. This polarizability helps in stabilizing the transition state of the reaction.
• Against B: Steric hindrance is more relevant for the approach of the nucleophile (in substitution reactions) rather than being a key attribute of a leaving group itself.
• Against C: Higher electronegativity (not lower) can be favorable in some cases as it can help in withdrawing electron density (e.g., in halides like \( \text{I}^- \) which is a good leaving group and is relatively electronegative compared to some other species).

Answer:

A. The departed leaving group should have low basicity.
D. The leaving group should be highly polarizable.