18.3 EAS Ortho-Para Directors vs EAS Meta Directors | Organic Chemistry

Chad gives a thorough presentation on Ortho-Para directors and Meta Directors in EAS Reactions. He begins by identifying electron-donating groups and electron-withdrawing groups and showing how electron-donating groups are activating groups in EAS reactions, whereas electron-withdrawing groups are deactivating. He provides a table of benzene substituents which can be used to predict relative rates of reactivity in EAS reactions. Chad shows how electron-donating groups stabilize the sigma complex intermediate in EAS reactions, whereas electron-withdrawing groups destabilize the sigma complex.
He then shows how electron-donating groups stabilize the sigma complex most when substitution occurs at the ortho and para positions explaining why they are ortho-para directors. He then shows how most electron-withdrawing groups destabilize the sigma complex the most when substitution occurs at the ortho and para positions explaining why they are meta directors. He also points out how halogens are the exceptions in that they are ortho-para directors though electron-withdrawing groups.
Finally, Chad shows several examples of how to predict the products of EAS reactions with substituted benzenes.
I've created an organic chemistry page that organizes all my videos by chapter - just an easier way for you to watch my KZbin videos. Check it out at www.chadsprep.com/chads-organic-chemistry-videos/
00:00 Lesson Introduction
00:54 EAS Activating Groups vs EAS Deactivating Groups
07:32 EAS Electron-Donating Groups | EAS Ortho-Para Directors
19:46 Halogens: EAS Electron-Withdrawing Groups and EAS Ortho-Para Directors
22:23 EAS Meta Directors
25:37 Special Reactivity of Aminobenzenes in EAS Reactions
28:54 EAS Predicting the Products Example #1
30:54 EAS Predicting the Products Example #2
32:38 EAS Predicting the Products Example #3
33:24 EAS Predicting the Products Example #4
36:28 EAS Predicting the Products Example #5
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Glad it was helpful!

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Glad to hear it, Soso Rob!

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[@Wuocwukong]

12:31 can you explain more specifically why the attack of E+ makes the metha carbon becomes more positive please. thank you a lot

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Thank you so much!

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You're welcome, Hailey!

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Most welcome, Laila.

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Glad the channel is helping you!

[@luke_MacLaughlin]

Weirdly got this concept delivered before the five EAS types

[@ChadsPrep]

Hope you found it helpful Luke! :)

[@asmaahmed316]

which among the following is the most deactivating group aromatic substitution reaction (Please rank the alternatives from strongest to weakest)? A. -NR3 B. -SO3H C. -NO2 D. -CN.

[@user-qs8he1ml3k]

Do electron withdrawing groups destabilize the benzenes in EAS as a result of withdrawing the electron density (and therefore making the conj base of a phenol, for instance, more stable and therefore worse as a nucleophile)? Or is it because the electron withdrawing effects destabilize the carbocation intermediate?

[@ChadsPrep]

Both!!! Very nice reasoning on both parts. Electron withdrawing groups lower the energy of electrons making 😊nucleophiles more stable and less reactive. But the sigma complex, i.e. the carbocation intermediate in EAS reactions, which is already electron-deficient, is destabilized by these electron-withdrawing groups. Essentially, exactly what you said!

[@user-qs8he1ml3k]

Appreciate the quick response and thanks. Your videos are actually going to make my career, I've seen basically all of them@@ChadsPrep

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That's awesome and I know you are going to be an asset in any career you pursue :)

[@Czar_Char]

isn't phenol supposed to have 5 resonance structures?

[@max3eey]

Yes, but not all of them are equally as stable. The lower energy ones are preferred for EAS.

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Chad's the name - welcome to the channel!