Preferential meta para and ortho positions substitutions.

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Discussion Overview

The discussion revolves around the substitution patterns of bromine in methyl phenyl amine and methyl phenol when reacted with aqueous bromine. Participants explore the influence of activating groups on the electrophilic substitution reaction, considering both theoretical and practical aspects of organic chemistry.

Discussion Character

  • Homework-related
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that the substitution position will depend on the strength of the activating groups, specifically comparing the methyl and amine groups.
  • Another participant agrees that there are competing activating groups and questions which one is stronger and what kind of director each is.
  • It is noted that both methyl and amine groups are ortho and para directing due to their activating nature, but uncertainty remains about which group is stronger.
  • A participant mentions that resonance donation typically has a stronger directing effect than hyperconjugation, implying a potential hierarchy of activating effects.
  • A later reply expresses a lack of familiarity with resonance concepts, indicating that the discussion may be advanced for some participants.
  • One participant emphasizes the importance of understanding resonance to grasp substituent directing effects, suggesting that without this knowledge, one might be memorizing rather than understanding.
  • A participant inquires about the educational context, revealing they are in their last year of high school and studying organic chemistry at a level that may not cover all necessary concepts.
  • Another participant expresses surprise at the teaching approach that omits foundational concepts, suggesting that students should be able to find information about activating groups in textbooks or online.

Areas of Agreement / Disagreement

Participants generally agree that the strength of the activating groups influences the substitution pattern, but there is no consensus on which group is stronger or how to evaluate their effects without understanding resonance.

Contextual Notes

Some participants express limitations in their understanding of resonance and its role in determining the strength of activating groups, which may affect their ability to fully engage with the topic.

Kushal
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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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Kushal said:
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?
 
both methyl and amine groups are ortho and para directing because they are activating groups.

but i don't know which one is stronger.
 
this is something you could find pretty easily in your orgo text, but resonance donation typically has a stronger directing effect than hyperconjugation.
 
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
 
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?
 
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,...
 
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.
 
alright...thnks:)
 

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