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If the benzene is a substituent by itself, does it have electron withdrawing effects or does it donate?
What about pi bonds?
Thank you!
What about pi bonds?
Thank you!
If the benzene is a substituent by itself, does it have electron withdrawing effects or does it donate?
What about pi bonds?
Thank you!
If the benzene is a substituent by itself, does it have electron withdrawing effects or does it donate?
What about pi bonds?
Thank you!
a phenyl group is electron withdrawing because aromatic rings are electron deficient. a benzyl group is usually electron donating because you have an electron-rich methylene group attached directly to the carbon you're referencing.
I don't know what you mean by "What about pi bonds?" though, sorry...
a phenyl group is electron withdrawing because aromatic rings are electron deficient. a benzyl group is usually electron donating because you have an electron-rich methylene group attached directly to the carbon you're referencing.
I don't know what you mean by "What about pi bonds?" though, sorry...
Not quite. A phenyl group is almost always slightly electron donating by induction. Aniline makes the benzene ring a better nucleophile, because its lone pair is in conjugation with the ring. The nitrogen of aniline is a relatively poor nucleophile due to this conjugative stabilization through resonance, not because benzene is exerting an electron-withdrawing inductive effect.no, this is a misconception, phenyl groups are well-known to be slightly electron withdrawing, but they can stabilize carbocations benzyllic to them because of resonance. in other words, they stabilize a carbocation because the phenyl group, despite being electron deficient, is electron rich when compared to a carbocation. in other words, a carbocation is more electron withdrawing than a phenyl group so the net effect is that the phenyl group donates electron density into the carbocation.
so what I really should have said is that a phenyl group can be electron donating if it is in a configuration where it can undergo resonance with a more electron-poor species. but for a neutral or an anionic species, the phenyl group is almost always electron withdrawing. for example, aniline, which is neutral, is much much much much much much less nucleophilic than an aliphatic amine like methylamine or ethylamine, etc. Why? because the phenyl group of aniline is electron withdrawing. So, in summary, electron-withdrawing ability is relative, but in most cases, a phenyl group will actually function as an electron withdrawing group. There are notable exceptions, like benzylic carbocations, but for the most part they function as electron withdrawing groups.