Stability of Carbon radical?????????

[Bernoull]

I understand wht accounts for the trend in Carbocation (C+) stability, 3*>2*>1*>CH3 bcos

1. Alkyl groups are electron donating so they neutralize the + charge on the C+ and they more substituents attached to the C+ the greater the surface area to spread the + charge = less charge density = more stability.

I can't think of a way to justify Carbon free radical (C*) stabilty which also follows 3*>2*>1*>CH3. Since the R groups in 3* are electron donating, this will stabilize a negative charge on an electronegative atom but is C considered electronegative relative to CH3 substituents. I hope my question makes sense...

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[JaySmoove]

you are exactly right! The stability of carbon radicals follow the exact same pattern as the stability of carbocations. 3*>2*>1*>CH3. This is due to HYPERCONJUGATION and THE INDUCTIVE EFFECT. Also, a carbon radical is not electronegative compared to the R groups. The center carbon simply has one electron in its 2P orbital. This is highly unfavorable, and results in the attraction of electron density from its R groups. This does not mean that the center carbon is more electronegative. Only that the half filled 2p orbital is very unstable.

 

[Bernoull]

Thanks a bunch for the input. After more thought and thanks to your posts, I can now see how the same factors (hyperconjugation, e' donating effects etc) can stabilize both C-cation and C-radical...