Electron withdrawing groups

[sacapuntas]

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I am trying to decide if nitrobenzyl is more or less electron withdrawing than trifluoromethyl when they are connected to a carbocation.

Any help would be greatly appreciated!

 

[DrRoyal Pains]

Thats a great question. I want to say nitrobenzene is more electron withdrawing, but with trifluoromethyl, F is more electronegative than the O on the nitro group, which I think would make it more electron withdrawing. Also, the N and O don't have a HUGE difference in electronegativity, but the C and F in trifluoromethyl do. I am going to have to BUMP this question ha.

 

[sacapuntas]

Thats a great question. I want to say nitrobenzene is more electron withdrawing, but with trifluoromethyl, F is more electronegative than the O on the nitro group, which I think would make it more electron withdrawing. Also, the N and O don't have a HUGE difference in electronegativity, but the C and F in trifluoromethyl do. I am going to have to BUMP this question ha.

Yeah, its a tricky one. The other thing to consider is that you can draw all kinds of resonance structures with the nitro benzene. You can de-localize the + charge on the carbo cation which makes me think that it is probably more stable/less electron withdrawing.

 

[sacapuntas]

Bump...does anyone have any insight?