Chemical Forums

Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Gaba90 on December 30, 2020, 05:32:46 PM

Title: Phenyl group EDG or EWG
Post by: Gaba90 on December 30, 2020, 05:32:46 PM

Phenyl groups can be electron withdrawing and electron donating through inductive effect and resonance. In what situations are phenyl groups EWGs and/or EDGS? (ie. what is the nature of the atom the phenyl group is attached to)

Title: Re: Phenyl group EDG or EWG
Post by: Babcock_Hall on December 30, 2020, 06:32:22 PM

What are you thoughts, so far?

Title: Re: Phenyl group EDG or EWG
Post by: Gaba90 on December 31, 2020, 10:41:25 AM

Quote from: Babcock_Hall on December 30, 2020, 06:32:22 PM

What are you thoughts, so far?

I am thinking the phenyl group is normally electron withdrawing group by induction due to the higher electronegativity of sp2 carbon atoms. For example in propyl benzene, the propyl group is an EDG and the phenyl group is an EWG.

However if a phenyl group is adjacent a positive or negative charge, it stabilises it by resonance, which is why benzyl cation and anion are both more stable than other alkyl cations and anions ?

Title: Re: Phenyl group EDG or EWG
Post by: Babcock_Hall on December 31, 2020, 11:06:30 AM

I agree.  If one judges by Hammett σ_meta values, the phenyl group is slightly electron-withdrawing.