Ans: Resonance Structures: Checking Answers Correctness

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Discussion Overview

The discussion revolves around the correctness of answers related to resonance structures in organic chemistry. Participants explore the effects of inductive and mesomeric influences on electron distribution and resonance, addressing specific questions and examples provided by the original poster.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • The original poster questions the correctness of their answers regarding resonance structures and discusses the inductive and mesomeric effects on electron behavior.
  • One participant asserts that the original poster's understanding of the mesomeric effect is incorrect, specifically regarding the role of -OR as an electron donating group.
  • The original poster expresses uncertainty about the correctness of their answers, particularly for the eighth question.
  • Another participant clarifies that all resonance structures involve mesomeric effects, even when a pi bond is conjugated with a lone pair, and points out specific errors in the original poster's reasoning.
  • There is a discussion about the transfer of pi bond electrons, with emphasis on the limitation of transferring electrons to saturated carbons.
  • One participant highlights the importance of maintaining charge balance in resonance structures, specifically mentioning a positive charge on nitrogen in one of the examples.

Areas of Agreement / Disagreement

Participants express differing views on the correctness of specific resonance structures, with no consensus reached on all answers. Some participants agree on certain structures being correct, while others challenge the original poster's interpretations and reasoning.

Contextual Notes

Participants reference specific resonance structures and their characteristics, but there are unresolved aspects regarding the application of mesomeric and inductive effects. The discussion involves assumptions about charge conservation and the nature of electron movement in resonance.

Who May Find This Useful

Students and individuals studying organic chemistry, particularly those interested in resonance structures and electron effects in molecular systems.

chemJan2021
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Summary:: I would like to know if my answers of each resonance structure of the eight questions is correct or not.
I think the Inductive effect (induction) attracts electrons and affects up to three bonds as electron attracting group.
And the Mesomeric effect affects Pi- bonds as long as there are Pi-bonds.
And the Electron donating group (-NR2, -OR, -R) pull the electrons and the Electron attracting group (-NO2, -CO-, -COO-, -CN, -SO3R, halogen) attract the electrons.



 

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2 is right, the others are wrong (or 1 is incomplete). -OR is mesomerically electron donating, not attracting. Try drawing in all the lone pairs and counting electrons, and see why your suggested structures are wrong.
 
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Thank you for useful comments!
I really appreciate it! I’ll check and try drawing to get to know correct answers.
 
I rethink the answers of these seven questions of resonance structure (1, 3-8). I hope these are correct.
I think as there are only one Pi-bond in 1-7 questions, there is no mesomeric effect in these questions.
I couldn’t understand the answer of the eighth question is wrong. The answer of the eighth question is correct?
 

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They are all mesomeric; it's just that the pi bond is conjugated with a lone pair rather than another pi bond. 1-4 and 8 are correct. (In 8, the unconjugated pi bond is not involved in the resonance.) In 7 you have omitted the positive charge on the N. 5 and 6 are wrong - you are trying to move the pi bond to a saturated carbon. They are analogous to 3 and 4.
 
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Thank you for your insightful comments!
I understand mesomeric effect in these resonance structure.
I understand the electrons of pi bond cannot be transferred to a saturated carbon and but to the next carbon of the pi bond. I think the electrons of pi bond can be transferred to a next cation of carbon but not to a saturated carbon.
I appreciate your quite useful teaching!
 

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These are now correct, except that there is a positive charge on the N in the RHS of 6. Remember to keep the total charge constant!
 
Thank you for your useful comment!
I’ll try to check to keep the total charge constant.
I put positive charge on the M in the RHS of no.6.
Your clear explanation helped me understand these resonance structures, thank you!
 
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