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Questions tagged [aromaticity]

For questions about the concept of aromaticity. Do not use for reactions of aromatic compounds.

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Nonplanar polarization in allenes and aromatic compounds

I recently came across this elaborate article on electrophilic aromatic subsitution. In the third chapter "General mechanistic considerations in electrophilic aromatic substitution" the ...
jona173's user avatar
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What causes the four proton signals closest to the carbonyl in tetraphenylcyclopentadienone to appear more upfield than the other 16 aromatic protons?

What causes the four proton signals closest to the carbonyl in tetraphenylcyclopentadienone to appear more upfield than the other 16 aromatic protons? It's my current understanding that the carbonyl ...
E B's user avatar
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Aromaticity in Carbene compounds?

how do i check aromaticity in carbene molecules? i have never come across such a question and am not even sure if huckel's rule is valid here. any help would be appreciated!
bromocresol's user avatar
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1 answer
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Is the 4H-Pyran Cation aromatic?

I guess I'm just trying to understand what "cyclic resonance" really means, from all the examples I've come across its always a cyclic system where the pi-electrons go all around the ...
pointlessHumility01's user avatar
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1 answer
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ease of dehydration [closed]

ease of dehydration for the following alcohols is? I understand the most easiest would be for III, but shouldn't it be easier for I than for II? because II forms an anti aromatic compound? But the ...
user145228's user avatar
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1 answer
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Why is o used for hydroxy groups in IUPAC naming instead of saying 2-hydroxy [closed]

For this question, i marked compound II correct as 2-methylbenzaldehyde and got the question correct, but for compound I, i marked it wrong and suggested the name to be 2-hydroxybenzaldehyde. I got ...
Snehal Bhadani's user avatar
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25 views

Is this fused ring molecule aromatic? [duplicate]

In my notes, I can see that it is listed as anti-aromatic because of the 16 electron ring current that would be formed on the periphery of the entire molecule were the right benzene ring drawn in the ...
Bytes Per Second's user avatar
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Is 2,5-dimethylidenecyclopent-3-en-1-ide aromatic?

Ah yes, the age-old question. I understand from previous posts on this website that aromaticity can't be defined with using four rules. But I was curious about this particular anion: It certainly ...
Samuel Lee's user avatar
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Aromaticity of a fused ring compound

On a test, I marked this as aromatic, but the answer key says it's wrong. My thought process: It has 10pi electrons, so it follows Huckel's rule All carbons are sp2 hybridized It is cyclic Every atom ...
nidhishtyagi's user avatar
2 votes
1 answer
98 views

Is pentalene stable at room temperature?

Pentalene is planar, conjugated and has 8 π-electrons on its periphery, so it can be anti-aromatic. But if we polarize either of the π-bonds adjacent to the central C−C bond, the other ring will ...
shur's user avatar
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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 ...
Garv Chaudha's user avatar
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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 $\...
Holin's user avatar
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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 ...
Ham Lemon's user avatar
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4 votes
1 answer
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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 ...
hemant kumar's user avatar
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1 answer
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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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6 votes
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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 ...
raavee's user avatar
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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 ...
ixaixim's user avatar
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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 ...
Sơn Nguyễn's user avatar
6 votes
1 answer
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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....
Evamentality's user avatar
2 votes
1 answer
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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 ...
Eneluza's user avatar
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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?
ThunderGlove's user avatar
4 votes
1 answer
841 views

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 $4n + 2$ ...
crisps's user avatar
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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 ...
Abhiram Cherukupalli's user avatar
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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 ...
Evamentality's user avatar
6 votes
1 answer
1k views

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 ...
MKJ's user avatar
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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 ...
ielnahhal's user avatar
2 votes
0 answers
162 views

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 ...
Brianna's user avatar
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2 votes
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253 views

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 ...
Integer's user avatar
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3 votes
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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 ...
Sage of Seven Paths's user avatar
12 votes
2 answers
2k views

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 ...
TRC's user avatar
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2 votes
1 answer
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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 ...
mateis's user avatar
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2 votes
1 answer
103 views

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 ...
C-Consciousness's user avatar
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1 answer
79 views

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 ...
Prayag Ranjan Sahu's user avatar
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0 answers
37 views

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 ...
C-Consciousness's user avatar
4 votes
1 answer
354 views

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 ...
Raghav Madan's user avatar
2 votes
0 answers
31 views

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 ...
C-Consciousness's user avatar
5 votes
1 answer
812 views

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) ...
TRC's user avatar
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6 votes
1 answer
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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 ...
Charles Taylor's user avatar
0 votes
1 answer
197 views

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. ...
Ashford6464's user avatar
4 votes
2 answers
490 views

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 ...
OneEyedMushroom's user avatar
4 votes
3 answers
306 views

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 ...
srinivasan ranga's user avatar
1 vote
1 answer
2k views

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 ...
WhySee's user avatar
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10 votes
1 answer
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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 ...
Vamsi Krishna's user avatar
0 votes
0 answers
64 views

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 ...
Swadhin's user avatar
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-4 votes
2 answers
778 views

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 ...
Srini's user avatar
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10 votes
1 answer
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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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5 votes
1 answer
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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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2 votes
1 answer
2k views

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 ...
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