4
$\begingroup$

I'm having trouble understanding why an ester is a meta directing/deactivating group.

I'm not talking about an ester with its oxygen bound to the ring, like an acylated phenol. I mean the R group is bound to the ring and the alkoxy group is bound only to the carbonyl carbon.

It seems to me like the pi electrons in the carbonyl pi bond could be pushed down and delocalized into the ring. Why is this not possible?

$\endgroup$
4
$\begingroup$

As your concept oxygen gets positive charge and that leads to least stability which is as follows:

enter image description here

$\endgroup$
  • 1
    $\begingroup$ Yes, nice reasoning. However, there are no transition states involved here, all of the structures you've drawn in your answer are resonance structures (the 3 different ones for the ester and the 2 for phenol) so they should be connected by resonance (double-headed) arrows. Simply put, some resonance structures contribute more to the overall description of a molecule than others. $\endgroup$ – ron Apr 28 '15 at 13:28
  • $\begingroup$ Yes your correct. I thought that directing can happening at any place that ortho para like.... Thats why i mentioned TS. And the double heade arrow can be used only when the charge from, charged particle, is migrating to form other charged particle. So here i have used single headed arrow from non-charged particle to charged particle (first resonance structure). Thanq u for ur valuable review. $\endgroup$ – Λjάγ Laggani Apr 28 '15 at 13:56
  • $\begingroup$ Double headed arrows should be used for all resonance structures regardless of whether there is charge separation or not. The single headed arrow indicates a reaction taking place which is not the case. $\endgroup$ – bon Apr 28 '15 at 19:11
  • $\begingroup$ Yes i agree, but here i mean that the resonance in b/w charged particles. Thank you $\endgroup$ – Λjάγ Laggani Apr 29 '15 at 0:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.