Questions tagged [aromaticity]
For questions about the concept of aromaticity. Do not use for reactions of aromatic compounds.
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Is -NR3+ really meta directing? [duplicate]
For electrophilic aromatic substitution, it is said that -NR3+ is meta directing, but since it only shows electron withdrawing inductive effect and inductive effect decreases with distance so it must ...
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Hückel's rule for FAD (isoalloxazine) electronic structure
Isoalloxazine is called aromatic in literature. It's a part of FAD cofactor. In some PDB structures it has flat geometry (3DK9) in some cases it has not (3GYJ).
I've applied Hückel's $4n+2$ rule for $\...
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What's the current of an aromatic ring?
Aromatic molecules like benzene have a ring current, created by the movement of electrons around the ring. This is most visible during proton NMR, when the magnetic field of the ring current opposes ...
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Non Aromaticty due to Cross Conjugated Systems
I was going through this site looking for some answer on aromatic character, definition and other ways of judging an aromatic compound, when is tumbled upon this question:
Are p‐xylylene and fulvene ...
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Comparison of acidic strength in organic compounds by assigning charges to rings
Generally we compare acidic strengths by comparing relative stability of negative charge formed by removal of acidic hydrogen. However I can't understand the following comparison
The solution given ...
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Aromaticity of [14]annulene
Our teacher had taught us that cis-trans-[10]annulene is non-aromatic. The reason he gave is due to repulsions between hydrogens, the structure is no longer planar
But later he told us that [14]...
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Do aromatic canonical structures make the overall compound aromatic?
Here, the compound itself appears to be non-aromatic, but if the double bond between the ring and the oxygen is broken into a single bond, with oxygen pulling the electrons towards itself and ...
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Encoding molecule bond information in matrix form
I have the following problem: I have a pentacene molecule and would like to encode its bond information into a matrix form, to feed it later on to a Machine Learning (ML) algorithm (a Graph Neural ...
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When can lone pairs participate in aromaticity? [closed]
Basically, I'm confused on when lone pairs can participate in aromaticity, by the Huckel definition. Why can lone pairs on a carboanion be aromatic? I thought carboanions are sp3 hybridized, and the ...
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Are there any aromatic systems that don't contain any rings?
I'm curious if there are any aromatic systems that don't contain any rings. I just wonder and want to know if there is any exception to the aromatic system.
I know the definition of aromaticity is ...
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How does aromaticity play out in carbon nanohoops?
Within the family of carbon phanes,one that has caught my attention is cycloparaphenylene. Considering that in practice it is just a segmented piece of a carbon nanotube, is must be aromatic in nature....
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Azulene Conjugation?
I'm trying to figure out how azulene is an aromatic compound; I understand it is cyclic, flat, and follows Huckel's rule, but I don't understand how it is conjugated.
I have circled what I believe to ...
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Is cyclobut‐3‐ene‐1,2‐diide aromatic?
I think cyclobut‐3‐ene‐1,2‐diide is non-aromatic since there are two sp3 carbons (carrying negative charge), but my source says it is aromatic. Why?
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Is 2-pyrone an aromatic compound?
I was told by my professor that α-pyrone is not an aromatic compound, but I count two π-electrons as well as one of the lone pairs on oxygen giving six total which would be one of Hückel's $4n + 2$ ...
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What is local and global aromaticity?
I was browsing through some research papers, I came across the terms locally and globally aromatic. What does it mean? I was thinking locally aromatic meant it was conjugated in a specific space not ...
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What is the inherent mechanism in carbocatalysis?
When checking non-metallic catalysis materials, one mentioned example is that of carbocatalysis; using heterogeneous carbon structure to catalyze a reaction (Not to be confused as a support surface ...
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Are 2-pyridone and cycloheptatrienide antiaromatic?
Determine which one of the following compounds is not aromatic:
I think 2-pyridone (preferred name: pyridin-2(1H)-one) (1) is non-aromatic. It already contains three double bonds. If I take the lone ...
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why is benzene ring ubiquitous in almost all the organic compounds [closed]
Could you please give me a reasonable cause why benzene ring is found in every organic compound in food, pharmaceuticals, dyes . In addition, benzene is a known canceriogen, why shouldn't it be toxic ...
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Why does the amide get priority over the nitro group in the sulfonation of N-(4'-nitro[1,1'-biphenyl]-4-yl)acetamide?
An amide group is a moderate activating group and the nitro group is a strong deactivating group. Why did sulfonation occur in the ortho position of amide, when it could have added to the meta ...
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Does 'aromaticity' apply to individual resonance structures or the hybrid?
When we define the aromaticity of a compound, is it meant to describe the resonance hybrid of the compound, or for individual resonance structures of the compound?
I think the latter is wrong because ...
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Organic chemistry aromatic compounds
How can we determine which of the above conpounds are aromatic . My teacher taught me to remove a hydrogen and shift the electrons but I did not understand it . Could someone help me so that i can ...
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Why is selenophene aromatic?
According to Wikipedia,
The selenophene molecule is flat and aromatic. Being aromatic, it undergoes electrophilic substitution reactions at the 2- or 2,5-positions. These reactions are slower than ...
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Aromaticity of 1,4-Dioxin
Structure of 1,4-dioxin is:
Wikipedia page says that it is non-aromatic.
Pubchem page shows its structure is planar.
In a planar structure, obviously there will be 8 (= $4n$) pi electrons in ...
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Why do electron-withdrawing groups deshield outer ring protons?
I understand that ring protons experience deshielding because the induced magnetic field (outside the ring) has the same direction as the external applied field, but shouldn't electron withdrawing ...
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How can Phthalocyanine be aromatic when it is not planar? [closed]
Even as Hückel's rule is not applicable in every scenario, especially in metallic clusters, it seems that organic structure need to be planar to show aromaticity. That being the case, Pubchem's ...
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Effect of substituents on aromatic character
Does the presence of substituents (electron withdrawing or electron donating) on an aromatic system have any effect on the aromatic character?
In other words, would it be correct to say that benzene ...
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Why is the synthesis of graphene through alkyne trimerization not viable?
I have been looking for a rationale on this as massive polycyclic aromatic hydrocarbons have been synthesized this way, and with Graphene just being an indefinite expansion of aromatic rings, this has ...
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Aromaticity in cyclic ketones
I have read that, cycloprop-2-ene-1-one is aromatic and cyclopent-2,4-dien-1-one is antiaromatic.
Basically this is visualized by visualizing the resonance structures of this.
Similarly if I apply ...
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Do contiguous monolayer aromatic structures retain the same magnetic susceptibility as the core constituents?
As the synthesis of Porphyrin monolayer strips is achievable, retaining the core aromaticity of the tetrapyrrole; does it still retain the same value of magnetic susceptibility of porphyrin? Does this ...
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Reaction of cyclooctatetraene with sulfuric acid
Problem
The correct statement is
(A) P & Q are aromatic compound and Q has $\mathrm{sp^3}$-hybridized carbon atom.
(B) P is aromatic with 10 π electrons and Q is aromatic with 2 π electrons.
(C) ...
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Is the lone electron pair of an amide nitrogen part of the π system when building a Hückel matrix?
Is the lone electron pair of the nitrogen atom part of the conjugated π system in the α,β-unsaturated amide pictured below?
Is there a general rule for choosing when to include a nitrogen atom in a ...
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Nitrogen with shortest bond length in histidine?
The question asks what nitrogen in the ring of histidine has the shortest bond length.
I was thinking that since it has resonance, the initial thought of the nitrogen with the $\pi$ bond is incorrect. ...
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Why is the polarity of the B-N bonds in borazine the reason for its reduced delocalisation of π electrons?
My professor mentioned that borazine is aromatic, but not as much as, say, benzene. The reason he gave for this was that the B-N bonds in borazine, being polar, inhibit resonance. He also mentioned ...
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Finding the major contributing tautomer of 1-(propan-2-yl)-1,2,3,5-tetrahydro-6H-pyrazolo[3,4-b]pyridin-6-one [closed]
I am having a problem generating the correct tautomer for 1-(propan-2-yl)-1,2,3,5-tetrahydro-6H-pyrazolo[3,4-b]pyridin-6-one. I am told by my collaborator that the one I am generating is wrong.
I am ...
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Why is the tropylium anion non-aromatic? [duplicate]
Recently I came across a question asking which compounds are anti-aromatic. This was one of the options:
I’m confused as this is not an answer. I think the lone pair electrons on the carbanion ...
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Aromaticity of fused rings
I understood how to find aromatic nature of single aromatic rings (like benzene) or that of combination of rings which are independently aromatic, such that the electrons of one ring do not enter into ...
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Bond lengths in Fullerenes [duplicate]
I came across this about fullerenes-
All carbon atoms are equal and the undergo sp2 hybridisation. Each carbon atom forms three sigma bonds with three other carbon atoms. The remaining electron at ...
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What is the double bond equivalence of the following compound?
What is the double bond equivalence of the given compound? The given answer is 14 (8 pi electrons and 6 rings = 14 DBE). But why isn't the lone pair on nitrogen considered?? The lone pair on nitrogen ...
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Why is quinone mono oxime more stable than 4-nitrosophenol?
When we do nitrosation of phenols, we get para-nitrosophenol as the major product, which tautomerises to quinone mono oxime. This article states that it largely exists in the quinonoid form.
My ...
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Aromatic Character in Percentage?
I was just searching whether Uracil is aromatic or not and in this link$^1$ it is said that (from the abstract):
High-level computational methods were tested for the enthalpy of hydrogenation of ...
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Aromaticity of Caffeine
In the Caffeine molecule, is aromaticity confined only to the 5 membered ring? The entire molecule is planar and the 6 membered ring also seems to have 6π electrons.
The entire molecule has 10π ...
user102687
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Bonding in 1,4-dihydro-1,4-diborinine
In most aromatic compounds (e.g. benzene), their $\pi$-bonding molecular orbitals are completely occupied and their antibonding molecular orbitals are unoccupied. I'm wondering if there are any ...
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How is 4H‐1,4‐oxazocine aromatic?
I’ve found 4H‐1,4‐oxazocine in my chemistry book and I’m perplex as it states as aromatic:
I can count six electrons on p orbitals which could satisfy Hückel’s $n = 1,$ but the oxygen is sp3-...
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Why is 11-oxabicyclo(4.4.1)undeca-1,3,5,7,9-pentaene aromatic?
I have been told by my instructors that for a compound to be aromatic, it must be planar. In this given molecule the oxygen seems to be out of the plane of the conjugated system: how can it still be ...
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Is azonine planar?
I came across aza[9]-annulene, which is given to be aromatic. I can clearly see it follows Hückel's rule with 8 π-electrons in the ring and the lone pair of nitrogen.
But the thing that concerns me ...
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How come Cyclopropenylhydroxide exists and not cyclopropenol?
I'm currently studying aromatic compounds via online recorded lectures, and my teacher brought up about cyclopropenol and cyclopropenylhydroxide while teaching carbocylic non benzenoid compounds. He ...
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Does cyclooctatetraene also have a diradical anti-aromatic electronic state?
I read that the molecular orbital diagram of cyclobutadiene predicts that it should have a diradical nature as it has two unpaired electrons in two degenerate non bonding orbitals (one in each).
Why ...
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Why aren't the pi electrons delocalized in cyclopropene?
I was searching on the internet whether cyclopropene is aromatic or not. I found out that the electrons are not delocalized, causing the molecule to be non-planar and so forth, a lot of reasons.
But I ...
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Why is borole not considered aromatic
I came across a problem which stated that borole isn't aromatic. I thought that borole is similar to pyrrole so it should be aromatic, but that isn't the case. Can I know why isn't it aromatic?
I was ...
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Cross-conjugation and aromaticity in pyrene
I have read about non-huckel double bonds and clar's rule, but what made me confuse is that huckel's perception gives me the feeling that central bonds in polycyclic aromatic hydrocarbons (ex: pyrene) ...
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