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Preferential meta para and ortho positions substitutions.

  • Thread starter Kushal
  • Start date
  • #1
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Homework Statement



If i have 4 methyl phenyl amine and i add aqueous bromine. where will the bromine atom substitute.

And would adding aqueous bromine to 3 methyl phenol have a different reaction/observation.

Homework Equations





The Attempt at a Solution



I think it will depend on which is a stronger activating group. the methyl or amine group.

both organic compounds react similarly with bromine, with the same observations.
Discharge of reddish brown colour + acidic fumes of HBr.

the reaction is electrophilic substitution in both.
 
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Answers and Replies

  • #2
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I think it will depend on which is a stronger activating group. the methyl or amine group.
Exactly. There are two competing activating groups; therefore the addition will most likely occur at the position that is favored by the most activating group. So which one is stronger? What kind of director is it?
 
  • #3
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both methyl and amine groups are ortho and para directing because they are activating groups.

but i don't know which one is stronger.
 
  • #4
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this is something you could find pretty easily in your orgo text, but resonance donation typically has a stronger directing effect than hyperconjugation.
 
  • #5
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what you saying is advanced chemistry for me!! we don't do resonance.

but can you tell me which groups are stronger and which are weaker?!

thnks
 
  • #6
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You are asking a question from a second semester organic chemistry course. It's silly to even think about this question if you haven't already covered the prerequisite concepts to understand it. In order to understand a substituents directing effects you absolutely need to think about resonance, otherwise you are just blindly memorizing.

What year are you in school?
 
  • #7
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i'm in last year of high school. we do cambridge A levels. sometimes they give organic questions with different activating groups attached to a benzene ring and where a slight knowledge of which activating/deactivating group is stronger and weaker might be very helpful, at least to understand the problem.

we also study many reactions without getting into the mechanisms: elimination rxns,...
 
  • #8
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It's quite strange that they would teach you like that without covering the concepts that make it understandable... anyway, you can easily find in a textbook, or on the internet, which group is a stronger activator.
 
  • #9
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alright.....thnks:)
 

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