Can an Electron Withdrawing Group(EWG)(like NO2, F, Cl, OH, etc.) behave as a Electron Donating group(EDG) in a compound where a carbocation is present in order to stabilise it?

Does the position where it is present or distance from the carbocation affect it's behaviour as an EWG or EDG?

I feel that it should behave as an EDG as carbocation is electron deficient so it has a greater tendency to accept an electron.

Can we say a similar thing that an EDG behaves as an EWG in presence of carbanion as it has excess electrons?


Of course not. That's why it is called EDG or EWG. It tends to destabilize it more in the absence of other effects like resonance and hyperconjugation.

  • $\begingroup$ I'm afraid this may be an oversimplification; atoms care not for how we categorise them. For example, the fact that halide substituents on a phenyl ring are deactivating/electron-withdrawing yet ortho/para-directing suggests there can be simultaneous electron-withdrawing and electron-donating effects in operation, which in this case happens to have a net withdrawing effect. Now what if a bromine atom was linked to 2,4,6-trinitrobenzene? Or a pyrimidine ring? Would it still have a net electron-withdrawing effect into the ring? I have wondered this for a while myself. $\endgroup$ – Nicolau Saker Neto Oct 24 '18 at 8:48

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