Questions tagged [resonance]

Resonance refers to the representation of the electronic structure of a molecular entity in terms of contributing structures. The tag should be applied to any question that concern resonance structures or resonance energy. This tag should not be applied to questions about aromatic compounds (use the [aromatic-compounds] tag instead)

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18
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1answer
3k views

Why does depurination happen at a higher pH (or under less harsh conditions) than depyrimidation?

I've always wondered why the N-glycosidic bond, which connects the adenine or guanine purine bases to their sugars, was the easiest to cleave via acid hydrolysis, or why purines have the lowest ...
10
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2answers
8k views

Ozone resonance structure: differing opinions

I've always thought that the two-form resonance structure of ozone was the scientific concensus (from Wikipedia]: Then today I found two other opinions. A three-form structure: And a four-form ...
7
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1answer
4k views

Hyper conjugation in acetic acid?

While comparing the relative stabilities of acetic acid and formic acid why don't we consider the 3 possible hyper conjugative structures which would stabilize the positive charge on carbon thus ...
5
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1answer
13k views

Resonance structures of some aromatic compounds

Do compounds like tropolone, furan, and thiophene (which are aromatic) show resonance? If yes then what are the resonance structures that can be drawn? Also, do all aromatic compounds show resonance?
4
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1answer
6k views

Why can't the conjugate base of benzoic acid be stabilized by conjugation with the aromatic ring?

All the carbon and oxygen atoms are sp2 hybridised and can have a p orbital in the correct plane yet only conjugation of the COO- group occurs. I can't think why. I can't draw resonance structures for ...
1
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3answers
28k views

Why is meta-nitrophenol less acidic than para-nitrophenol? [closed]

My professor said while explaining the acidic nature of phenol that meta-nitrophenol is less acidic than para-nitrophenol, and gave the reason that resonance doesn't play on meta, but I didn't get it.
17
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3answers
58k views

What are the correct resonance structures of nitrous oxide?

There was a question in one of my exam papers to draw the resonance structures for $\ce{N2O}$. These are the ones I drew, but they were not awarded marks: The ones in the marking scheme are as ...
15
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2answers
821 views

Edges of graphite

I've been asked this question a few times, and while I think I know the answer, I'd like to know more. Graphite, as we know, is a sheet polymer. Since polymers are bound to be finite by physical ...
5
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2answers
8k views

Why is only one lone pair in imidazole delocalised?

I was wondering why only one of the nitrogen lone pairs in imidazole is involved in the delocalized π-system. Specifically, I was wondering why it is that lone pair B in particular is delocalized, ...
4
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1answer
4k views

What is “dancing resonance”?

While searching the Internet for information about the tricyclopropylmethyl carbocation, I found a site (askiitians.com) where it said that its stability was due to "dancing (superfast) resonance". ...
4
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1answer
5k views

Why are anti aromatic compounds unstable?

Just like aromatic compounds, anti aromatic compounds have several resonance structures and some of them are also conjugated ( 1,3-cyclobutene). Why is it that just having 4n electrons makes them ...
4
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2answers
373 views

Are there any acid-base indicators whose protonated and deprotonated forms have the same number of resonance structures?

This question asks about the color change of 7-hydroxyphenoxazone, the active compound in litmus paper, and the relation of that color change to the conjugated system in the molecule. In Klaus ...
1
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1answer
357 views

Aromaticity of 1,1'-bi(cycloprop-2-en-1-ylidene) and 1,4-dioxine

Are these Anti aromatic/aromatic or non aromatic? 1. Here, if we were to consider the resonating structure(s) with charge separation One ring is aromatic and other is anti aromatic, and secondly ...
11
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1answer
2k views

Which of the following has higher enol content?

Which of the following has higher enol content? The enol form of (A) and (B) is: Both the enols have hydrogen bonding. If the oxygen were to accept the pi electrns from carbon forming a carbocation ...
7
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2answers
14k views

Why is o-toluic acid (2-methylbenzoic acid) more acidic than benzoic acid? [duplicate]

Why does the methyl group at the ortho-position stabilize the carboxylate ion? I recognize that there will be a steric clash between the carboxyl group and the methyl group but I don't understand why ...
6
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2answers
4k views

Why should 2,6-Dimethyl-4-nitrophenol be more acidic than 3,5-Dimethyl-4-nitrophenol

I was trying to compare acidity of some organic compounds but can't understand some: Why should 2,6-dimethyl-4-nitrophenol be more acidic than 3,5-dimethyl-4-nitrophenol? I have been trying to ...
5
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3answers
468 views

Is 1,2-dihydronaphthalene “partially aromatic”? [duplicate]

I've learned that if any one ring of a structure like the below is aromatic, the whole compound is aromatic. But one of my friends suggested that such compounds cannot be aromatic and gave the ...
4
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1answer
1k views

Do acyl fluorides exhibit resonance donation or inductive withdrawal?

I know that in acyl chlorides, there is partial triple bond character in the $\ce{C=O}$ bond not because the chlorine is electronically donating (due to size mismatch with carbon) but because the ...
4
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2answers
7k views

Why does having equivalent resonance structures give more stability?

Although the phenolate ion has more resonance structures (4) compared to acetate ion (2), acetate is more stable because it has two equivalent resonance structures of same energy. Why does having ...
3
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1answer
7k views

Draw a simplified MO diagram for the pi system of Methyl vinyl ether

My attempt at the answers: i) 2 bond pairs and 2 lone pairs on oxygen atom therefore bond angle of slightly less than 109.5 degrees, around 104 degrees. ii) 120 degrees bond angle therefore sp2 ...
2
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1answer
4k views

Does resonance overrule hyper conjugation in terms of stability in alkenes? [closed]

Which of the following is more stable ? $\ce{CH2=C(CH3)-CH=CH2}$ $\ce{CH3-CH=CH-CH3}$ I was going for answer 2 because it has 6 hyper conjugative effects. I found the answer given to be ...
2
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1answer
7k views

Is acetate a weak base due to its resonance structure?

I just read that acetic acid is an exception to the general idea that the conjugate base to a weak acid is a strong base. The example says that the conjugate base of a weak acid will only be strong ...
2
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0answers
164 views

If both nitric acid and nitrate ion are stabilised through resonance, what makes the nitrate ion more stable in aqueous medium?

If both nitric acid and nitrate ion are stabilised through resonance, what makes the nitrate ion more stable in aqueous medium? Can the same argument be applied to nitrous acid and nitrite ion in ...
2
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1answer
777 views

Acidity of ester and benzoic acid

Can the oxygen in an ester participate in resonance donation? I think so, although the donation is slight. The hybridization is correct. However, resonance withdrawal by the ring via the oxygen doesn'...
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0answers
198 views

Can the effect of resonance on acidity be generalised?

A basic trend for acid: if the conjugate base is more stable, then the acid has a lower $\ce{pKa}$. Therefore, it would quite intuitive to think that resonance in the conjugate base will make the acid ...
0
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1answer
1k views

Lewis dot structures of CO2

I know the general Lewis dot structure of carbon dioxide is the one where there are two double bonds connecting oxygens to carbon. However the question is, does $\ce{CO2}$ have resonance structures? ...
-3
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1answer
559 views

O=Cl=O and O-Cl-O in a ring are not resonance structures?

Resonance structures are about moving electrons to form anions, cations, and new bonds. Structural isomers can be resonance structures. For example take phenyl ketone. Of course you can form ...