Which would be the stronger nucleophile in a polar aprotic solvent?

[lha08]

Homework Statement

Which would be the stronger nucleophile in a polar aprotic solvent?
a) H2O or H2S
b) (CH3)3P or (CH3)3N

Homework Equations

The Attempt at a Solution

I'm really confused because in my book, it says that in protic solvents, the larger atoms (I-) are stronger nucleophiles than smaller ones (F-). Then it says that it is opposite for when it is an aprotic solvent (e.g. F- is more nucleophilic than I-)
In this case, the answer to b) is H2S and c) is (CH3)3P, but shouldn't it be the opposite??

 

[omkar13]

The answers given for the question is correct and the concept given is wrong.consider protic solvent it consists of H+ ions since bonds between similar sized atoms is strong,the bond between smaller atoms will be stronger if F- is in polar protic solvent,it forms HF molecule which will be more stable than other halogen hydrides

 

[Blueshift5]

In a polar aprotic solvent, the stronger nucleophile would be the one that is more polarizable. This means that it has a larger electron cloud that is easily distorted, allowing it to attack electrophiles more easily. In this case, the answer to a) would be H2S and the answer to b) would be (CH3)3N.

In general, larger atoms or molecules are more polarizable than smaller ones. However, in the case of aprotic solvents, the smaller atoms or molecules can still be more polarizable due to their electron configuration. For example, (CH3)3N has a larger electron cloud than (CH3)3P, making it more polarizable and thus a stronger nucleophile in a polar aprotic solvent. Similarly, H2S has a larger electron cloud than H2O, making it a stronger nucleophile in this case.

It is important to note that nucleophilicity can also be affected by other factors such as steric hindrance and solvent effects. So, while larger atoms or molecules may generally be more nucleophilic in protic solvents, this may not always be the case in polar aprotic solvents due to other factors at play.