Organic Ortho/Para Question

[KennyL370]

So I'm doing some orgo problems and I can't find the answer to this no matter where I look. Maybe someone here knows? Sometimes when there is a donating group on a benzene ring the substituent gets added to the ortho position, and sometimes, it gets added to the para position ( I realize this is the whole point of calling it para/ortho), but my question is.... How do you know WHEN it goes para over ortho? I'm doing DAT Destroyer problems and I know it's activating so it will go para/ortho, but then I always pick the wrong one.

Any Help?

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[TheEpicFruitCake]

I learned in Ochem lab that ortho was usually going to be dominant because there are 2 ortho positions vs just 1 para position. Its like a 60-40 ratio though. If the substituent that you are adding is large however, there will be steric hindrance and favor para more. Just depends on the reaction

 

[dawg289]

Knowing that electron donating groups direct ortho/para is enough for the DAT. It's highly unlikely you'll be expected to know if it's ortho or para in a rxn.

 

[keewee981]

I went through the destroyer and i never saw an option that had ortho and para as separate options, if it was correct answer . Make sure that the groups already present on the ring are activators or deactivators. Some groups can change from meta to ortho/para if you reduce the functional group. Like NO3 to NH2.

 

[CabbageKid]

Another thing is that if there are already 2 substituents on the benzene ring, (for example there is a -CH3 (O/P director) on the 1-carbon and a -NO2 (M director) on the 3-carbon), you can NOT add ORTHO via the 2-carbon due to steric hinderance. In that situation, PARA will trump ORTHO.

 

[Dotoday]

Usually it is based on Steric hindrance, bigger groups will direct para.