carboanion stablization

[joonkimdds]

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carbocation and carbon radical have tertiary = benzylic = allylic > 2ndary >primary in terms of stablization.

I was wondering if carboanion is the same.

and if carbocation is tertiary but one is surrounded by 3 CH3 and other other one is surrounded by 3 phenol group, is the one with 3 phenol group more stable due to resonance?

 

[PooyaH]

first of all, tertiary is more stable than secondary carbocation! (maybe you meant primary) and yes a carbocation attached to 3 phenols is a lot more stable than a tertiary carbocation, which is attached to 3 R groups!

 

[joonkimdds]

how about carboanion???

 

[PooyaH]

That would be the opposite: primary>secondary>tertiary
But again I believe resonance and conjugation would stablize the carboanions as well!

 

[joonkimdds]

That would be the opposite: primary>secondary>tertiary
But again I believe resonance and conjugation would stablize the carboanions as well!

I had a question asking for the most stable carboanion and choices were
3 phenyl C:-
2 phenyl HC:-
1 phenyl H2C:-
H3C:-
(CH3)3C:-
and the correct one was 3 phenyl C:-
If first three were not there and we only had the last two then i guess the answer would've been H3C:- over (CH3)3C:-

 

[PooyaH]

I had a question asking for the most stable carboanion and choices were
3 phenyl C:-
2 phenyl HC:-
1 phenyl H2C:-
H3C:-
(CH3)3C:-
and the correct one was 3 phenyl C:-
If first three were not there and we only had the last two then i guess the answer would've been H3C:- over (CH3)3C:-

You're right! carboanion stability is the opposite of carbocation stability except when it gets to allylic and phenols!

 

[joonkimdds]

Thanks 🙂
Should I know which one is better among allylic, benzylic, and phenyl group?

I had a question asking which one is more soluble between COOH and phenol and the answer was COOH. But my organic chem as 2nd language says it's better to spread negative charge to 3 diff carbon than 1 oxygen even though oxygen is more electronegative so I am confused.

 

[PooyaH]

Thanks 🙂
Should I know which one is better among allylic, benzylic, and phenyl group?

I had a question asking which one is more soluble between COOH and phenol and the answer was COOH. But my organic chem as 2nd language says it's better to spread negative charge to 3 diff carbon than 1 oxygen even though oxygen is more electronegative so I am confused.

Always determine which one has more resonance structures, and that should be the most stable one!

COOH is more soluble! It is a lot more electronegative and a stronger acid than phenol, thus it must be more soluble!