Rank the following in order of decreasing nucleophilicity, putting the most nucleophilic first.

Question

Quizplus · Accepted Answer

In general, the nucleophilicity increases as the negative charge density increases and/or the steric hindrance decreases. In this case, III is the most nucleophilic because it has a negative charge on oxygen and the least steric hindrance. II is less nucleophilic because it has a negative charge on nitrogen, which is less electronegative than oxygen and thus less efficient at stabilizing the charge. IV is less nucleophilic than II because the lone pair on sulfur is less available for nucleophilic attack due to steric hindrance from the bulky tert-butyl groups. I is the least nucleophilic because it does not have a negative charge and only has a polarized C-O bond, which is not very reactive. Therefore, the correct order of decreasing nucleophilicity is III > II > IV > I, which is choice B.

Rank the Following in Order of Decreasing Nucleophilicity, Putting the Most