Is My Reasoning for Aromaticity Correct?

In summary, the conversation is about the application of Huckel's Rule to determine aromaticity in molecules. The first and second molecules are evaluated based on their number of pi electrons and both are found to not be aromatic. The last molecule is also not aromatic, but the reasoning is that it is not planar, which is a requirement for aromaticity according to the textbook. It is suggested that the steric interference between the NH group and oxon group may cause the molecule to be displaced.
  • #1
sashab
12
0

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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  • #2
sashab said:

Homework Statement


View attachment 79483

Homework Equations



Huckel's Rule: 4n +2 pi electrons

The Attempt at a Solution

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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:
  • #3
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!
 
  • #4
Maybe becoz of the steric interference between NH group and oxon group it might have been diS placed. .(not so sure abt this)
 

FAQ: Is My Reasoning for Aromaticity Correct?

1. What is aromaticity in organic chemistry?

Aromaticity is a chemical property of molecules that describes a special stability and reactivity associated with a particular arrangement of atoms called an aromatic ring. Aromatic compounds are characterized by having a cyclic structure of alternating single and double bonds, with a delocalized electron system.

2. How is aromaticity different from other types of chemical bonding?

Aromaticity is unique in that it involves a delocalized electron system, where the electrons are spread out over multiple atoms rather than being localized between two specific atoms. This results in increased stability and unique chemical properties, making aromatic compounds important in many areas of chemistry.

3. What are some common examples of aromatic compounds?

The most well-known example of an aromatic compound is benzene, but other examples include toluene, naphthalene, and phenol. Aromatic compounds are found in many natural products, including essential oils, and are also used in the production of plastics, dyes, and pharmaceuticals.

4. How is aromaticity determined experimentally?

The most common experimental technique for determining aromaticity is through nuclear magnetic resonance (NMR) spectroscopy. Aromatic compounds show a characteristic shift in their NMR spectra, known as the chemical shift, due to the presence of the delocalized electron system. Other spectroscopic techniques, such as UV-Vis spectroscopy, can also be used to determine aromaticity.

5. Are all compounds with alternating single and double bonds considered aromatic?

No, not all compounds with alternating single and double bonds exhibit aromaticity. For a compound to be considered aromatic, it must meet certain criteria, such as having a delocalized electron system and fulfilling the Huckel's rule, which states that the number of pi electrons in the ring must equal 4n + 2, where n is any integer. Compounds that do not fulfill these criteria are considered to be non-aromatic or anti-aromatic.

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