Multiple Choice
Which of the following charged nucleophiles is most reactive in solvent?
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8. Elimination Reactions
Nucleophiles and Basicity
Multiple Choice
Which of the following correctly ranks the nucleophilicity of the species , , , and in water from greatest to least?
A
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B
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C
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D
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Verified step by step guidance1
Understand that nucleophilicity refers to the ability of a species to donate a pair of electrons to an electrophile, and it depends on factors such as charge, electronegativity, solvent effects, and polarizability.
Recognize that the species given are halide ions: fluoride (F\(\textsuperscript{\-}\)), chloride (Cl\(\textsuperscript{\-}\)), bromide (Br\(\textsuperscript{\-}\)), and iodide (I\(\textsuperscript{\-}\)), all negatively charged and differing mainly in size and polarizability.
Consider the solvent effect: in a protic solvent like water, nucleophilicity trends differ from basicity trends because smaller ions like F\(\textsuperscript{\-}\) are strongly solvated (surrounded by solvent molecules), which hinders their nucleophilicity.
Recall that in water, nucleophilicity increases down the group because larger ions like I\(\textsuperscript{\-}\) are less solvated and more polarizable, making them better nucleophiles despite being less basic.
Therefore, the correct ranking of nucleophilicity in water is: \(\mathrm{I}^- > \mathrm{Br}^- > \mathrm{Cl}^- > \mathrm{F}^-\), reflecting the balance of solvation and polarizability effects.
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