Ochem:deactivating, activating, aromatic substitutions

[A6project]

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I understand those most activating/deactivating groups. Nevertheless, how do you know if ortho- will be a major over para- or vice versa?

for example, lets just say -NH2 is on a benzene. is there a way to figure out whether the structure will yield "major para-"products or "minor ortho"products?

Or am I too concerned about a little things and should I focus more on ortho/para vs. meta????

thanks!!!!

 

[orgohacks]

I understand those most activating/deactivating groups. Nevertheless, how do you know if ortho- will be a major over para- or vice versa?

for example, lets just say -NH2 is on a benzene. is there a way to figure out whether the structure will yield "major para-"products or "minor ortho"products?

Or am I too concerned about a little things and should I focus more on ortho/para vs. meta????

thanks!!!!

Probably the latter. Know ortho/para vs. meta and you'll be fine.

Hard to think of good examples which are dominant for ortho or para. You'll always get mixtures to some extent. sterics favor para, statistics favor ortho.

 

[Baylor2011]

Always a mixture but para predominates. In order to guarantee putting something in the ortho position you can put a meta director in the para
position that you know how to get off (SO3H), then orthos the only place the next substituent can go. Treat with H2SO4/steam and the SO3H group will come off.