I am supposed to determine which of the following groups that will be the most nucleophilic – -OH, -NH
2 or -SH – in a reaction where
a) acetone
b) water
is used as a solvent.
a) Acetone is a polar aprotic solvent, right? And there will probably be much more solvent. So, the most basic group must be the correct answer to the question. -NH
2 is more basic than -OH, but what about -SH? It's much less electronegative than both N and O, so I as far as I can see, it must be the worst nucleophile of these three groups. The solution of this problem, however, says it's the best one, which makes me hesitate. Anyone who knows for sure?
b) Water is definitely protic, which means that that polarizability and size matters. The sulfur atom in -SH is larger than nitrogen and oxygen, and more polarizable, so I guess it's the best nucleophile, followed by -OH and -NH
2?