orgo help

[heywhatsup]

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Which of the following is the most stable carbanion? (Φ = phenyl group)
A. Φ3C:–
B. Φ2HC:–
C. ΦH2C:–
D. H3C:–
E. (CH3)3C:–


The ans is A. but i thought carboanion stability is the opposite of carbocation stability. wouldnt A be the least stable carboanion? HELP 🙁

 

[Decan]

Choice A would be a good carboanion because the phenyl group has a 6 conjugated p orbitals to spread the negative charge.

 

[Joey413]

Draw them all out try to see which one will have the most resonance structures possible..this one is going to be the more stable one since it can spread this negative charge all around... the more resonance structures the more stable..

 

[heywhatsup]

thanks

 

[whoaaitzkyle]

I thought carbanion stability was opposite of radical and carbocation stability. hrm...so does that mean carbanion stability is tert>2>1>meth then? I'm confused.

 

[orgoboy]

Note that when we have a conjugated system this serves to not only lend e- density to the system it also leads to an inductive effect, both of which stable the anion. The group with the ability to do this best was the answer with three phenyl groups.

 

[heywhatsup]

since carbon anion stability is opposite of carbocation stability, doest that mean that primary is more stable than tertiary?

what are the rules with anion stability?