Is My Reasoning for Aromaticity Correct?

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Discussion Overview

The discussion revolves around the concept of aromaticity in organic chemistry, specifically evaluating the aromatic nature of three different molecules based on Huckel's Rule and structural considerations. Participants are analyzing the criteria for aromaticity, including electron count and molecular geometry.

Discussion Character

  • Homework-related
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant argues that the first molecule is aromatic due to having 6 pi electrons and satisfying Huckel's Rule, while the second molecule is not aromatic because it has 16 pi electrons.
  • The same participant questions the aromaticity of the last molecule, suggesting that although it has 6 pi electrons, the overlap of p-orbitals with oxygen prevents resonance stabilization in the ring.
  • Another participant asserts that the last molecule is not aromatic because it is not planar, referencing their textbook as a source for this criterion.
  • A subsequent reply seeks clarification on the non-planarity of the last molecule, emphasizing that planarity is essential for aromaticity.
  • Another participant speculates that steric interference between functional groups may contribute to the non-planarity of the last molecule, though they express uncertainty about this reasoning.

Areas of Agreement / Disagreement

Participants express differing views on the aromaticity of the last molecule, with some focusing on electron count and resonance stabilization, while others emphasize the importance of planarity. The discussion remains unresolved regarding the aromatic nature of the last molecule.

Contextual Notes

Limitations include the lack of detailed structural information about the molecules in question, which affects the assessment of planarity and resonance. The discussion also reflects varying interpretations of aromaticity criteria based on different sources.

sashab
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Homework Statement


upload_2015-2-22_17-2-24.png


Homework Equations



Huckel's Rule: 4n +2 pi electrons

The Attempt at a Solution



I'm having problems with the last molecule. I said that the first molecule was indeed aromatic because it has 6 pi electrons and obeys the 4n + 2 rule. The second one is not aromatic because it has 16 pi electrons. But for the last molecule, my reasoning for why it's not aromatic is that although it has 6 pi electrons, the electrons in the p orbitals of the carbons from the carbonyls don't occupy the p-orbitals of the oxygen, the two p-orbitals just overlap. So I don't think the p-orbitals of those carbons count towards aromaticity in the ring because those orbitals overlap with the p-orbitals on the oxygens and not the p-orbitals of the adjacent carbons. I was thinking that those p orbitals don't contribute to resonance stabilization in the ring. There are indeed 6 pi electrons, but i don't think the conjugated pi-orbital system criteria is satisfied. Is my reasoning on the right track? Any help would be appreciated. Thanks!
 
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sashab said:

Homework Statement


View attachment 79483

Homework Equations



Huckel's Rule: 4n +2 pi electrons

The Attempt at a Solution

:[/B]

The last one is not a planar compound...my textbook says it must be a planar compound to be aromatic.
 
Last edited by a moderator:
sidarth siddhu said:
The last one is not a planar compound...my textbook says it must be a planar compound to be aromatic.
Could you please state why the last molecule is not planar? it is true that the compound must be planar to be aromatic!
 
Maybe becoz of the steric interference between NH group and oxon group it might have been diS placed. .(not so sure abt this)
 

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