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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Which resonance structure to use for writing curved arrow mechanisms?

If a structure with delocalized electrons participates in a reaction, which resonating structure do you use to write down the mechanism? Is using either equivalent? Is it preferred to use the ...
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Anitaromatic compounds: Why do they have lower stability? [duplicate]

What is the cause for some compounds like cyclobutadiene to be antiaromatic? I know they don't satisfy Huckle's rule but I don't understand why that leads to the decrease in stability of the ...
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The most stable resonance structure [duplicate]

I came across this question: Which is the most stable resonating structure of p-nitrosobenzene among the following? I have been taught about the priorities for resonance structure ...
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1answer
407 views

Does triphenylphosphine show resonance?

The lone pair of phosphorus and the double bonds in benzene looks to be in conjugation. Do the molecule show resonance? If so, how?
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Cyanamide mesomeric contributors

Which form of the cyanamide ion is more stable? As per the resonance rules, I find both of them equally stable as number of bonds is the same, more electronegative atom has negative charge and so on. ...
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3answers
133 views

Do conjugated double bonds take priority over a +1 formal charge?

Do conjugated double bonds take priority over a +1 formal charge? The first one is what I solved for (ignore the hexagon that has no double bonds attached to it), and the one below it is the answer ...
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292 views

Which carbocation is more stable?

Which one of Tropylium cation (cycloheptatrienyl carbocation) and Cyclopropylmethyl carbocation is more stable? Several references present opposing views on this topic, hence the confusion. Reasons ...
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How many valid resonance forms can be constructed for aniline?

Based on the above picture, it seems that there are four. However, I have two questions: Aren't the top right and bottom left forms simply mirror images of each other, and thus considered the same? ...
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Why does oxygen atom allow positive charge on its surface when its electron pair is in resonance with benzene ring?

Oxygen atom is a highly electronegative element. Why does oxygen atom allow positive charge on its surface when its electron pair is in resonance with benzene ring? The reason can be that its octet ...
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Why do these resonance structures explain meta-directing feature of Nitrobenzene but not other resosance structures?

Consider the following resonance structures of Nitro-benzene: It is written in the book that because the positive charge is always at $-o$ or $-p$ positions, Nitro group in benzene has meta directing ...
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Why is benzoic acid more acidic than p-chlorobenzoic acid?

We know that in case of halogens, inductive effect is more dominant than resonance effect. So, the -$\ce{Cl}$ on the para position will withdraw electrons by a -I effect and should make p-...
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Correct stability order of resonance structures

Question no 9 as far as I know none of the rules of relative order of stability apply to this( completion of octate,charge seperation etc.) So they all must be equally stable but the answer is (D)
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Are resonating structures real or not? [duplicate]

We say that hybrid structure is real. It has distinct properties as compared to its Resonating Structure. Is it because that all the experiments we carry out are on a sample, lots of molecules are ...
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Stability and resonance structures

In school they ask us to count the number of resonance structures in different organic compounds to determine it's stability. The one with more resonance structures is more stable. Is this notion ...
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3answers
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Why isn't this resonance possible in an imidazole ring?

My question is why isn't the resonance structure drawn in pencil on the right a valid one? My review book states that after initial protonation on the indicated nitrogen no resonance is possible.
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Why is the compound 3,4-dihydroxy-3-cyclobutene-1,2-dione more acidic than acetic acid?

Why is the compound 3,4-dihydroxy-3-cyclobutene-1,2-dione more acidic than acetic acid? I don't get how its resonance stabilization is far greater than that of acetic acid despite the fact that the ...
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2answers
957 views

Understanding how electrons are counted for lone pairs vs. bonds especially when understanding resonance?

This is taken from the book Organic Chemistry as a Second Language from page 35. In the following image: It is seen that when the electrons from the double bond are pushed into the lone pair ...
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Is cyclopropyl methyl carbanion also exceptionally stable?

I know that cyclopropyl methyl carbocation is exceptionally stable and in fact more stable than benzyl carbocation but I was wondering if it was the same case with cyclopropyl methyl carbanion. Is it ...
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Naphthalene v/s Anthracene reactivity

Both have similar resonance energy per ring, even Naphthalene has a little higher Resonance energy (127.5 KJ per mol per ring v/s 127 KJ per mol per ring ) Can we prove , why there is a small ...
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1answer
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How do I identify resonating structures for an Organic compound [closed]

Basically, my concepts regarding Resonance are not totally clear. I just need some help, on how to find the no. of resonating structures, given a molecule, and how do I draw those structures. Some ...
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Valid resonance contributors for 2-methylthiazole [duplicate]

There's a problem from an old exam that I was trying to do. The original structure is given on the left and they want all the possible resonance forms that have closed-shell atoms (octet for S) and ...
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3answers
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Hybridisation of terminal nitrogen in diazomethane

I have a few questions about the terminal nitrogen (highlighted in red) in diazomethane, $\ce{CH2N2}$. Is that nitrogen $\mathrm{sp}$ or $\mathrm{sp^2}$ hybridised? What type of orbitals do the lone ...
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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". ...
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Is Phenyl Carbocation very unstable? [closed]

Phenyl carbonation is said to be unstable because the + charge on it cannot be stabilized by Resonance or any other electronic effects, so my question is that if the resonance occurs in the direction ...
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1answer
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Most stable resonating structure of 1-nitro-4-nitrosobenzene

The most stable resonating structure of 1-nitro-4-nitrosobenzene is: In my view since in each case we have 4 charges and except in case 1 all have complete octets, so 1 is neglected. However, I am ...
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Which is the most acidic proton of (3Z)-3-ethylidenecyclopent-1-ene-1-carbaldehyde?

At first glance, I thought the most acidic protons would be the ones in red due to their proximity to the carbonyl. However, the answer key has the hydrogens in green as the most acidic. Can someone ...
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Resonance structures

I'm working with a certain molecule, and could see that it was only on the ether group that it was possible to make these resonance structures. First, I'd like to know if the structures are correct ...
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Determining the bond order

I have the following molecule. And I have to determine the decreasing order of bond order of $\ce{C_1-C_2,C_3-C_6,C_2-C_3}$ I know that I have to take into consideration the various resonating ...
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Which carbons in pyrrole have the highest electron density?

In pyrrole, which carbon atoms have the greatest electron density? In the resonance structures of pyrrole, all carbons can formally bear a negative charge, so it's not immediately obvious which one ...
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2answers
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What is the hybridisation of the carbons in the allyl radical?

The example I am talking about is $\ce{CH2CHCH2^.}$. To find the steric number and hence the hybridization, we use steric number = No. of lone pairs + number of sigma bonds. In this example, the ...
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1answer
121 views

Arrow pushing: why does the O become positive when its lone pair becomes a double bond?

In the following image: The oxygen's top pair of electrons forms a double bond. But in a covalent bonds, aren't the electrons shared? So won't the oxygen still have these $2$ electrons (that it ...
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Structure of nitric oxide

These are the two resonating strctures of NO given in my textbook. In the first resonating structure, oxygen is shown to have 9 electrons. How can that be possible since oxygen does not have the third ...
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2answers
413 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 ...
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1answer
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Does the carboxylate group show a positive or a negative inductive effect?

In the benzoate ion, does the carboxylate group show a $-I$ or a $+I$ effect? I learnt that the carboxylate group is a $-I$ group, but according to a website the carboxylate group in benzoate shows a ...
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Do Fermi resonances show in Inelastic Neutron Scattering spectra?

The Raman and FTIR spectra of a urea based mixture shows a strong Fermi resonance in the N-H stretching region, which difficults its interpretation. In an inelastic neutron scattering spectra of the ...
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1answer
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What are the resonance structures of methyl azide?

I am supposed to construct the major resonance structures of methyl azide, $\ce{CH3N3}$. I know that in compounds such as the carbonate anion $\ce{CO3^2-}$, resonance can be depicted by ...
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781 views

All resonance structures of the hydrogen molecule

This answer written by Jan says that "a professor of mine claimed to have drawn some 18 (or was it 80?) different resonance Lewis structures." Please reproduce those resonance structures of the ...
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1answer
226 views

how do electromeric / inductive effect theories compare with resonance

Back in high school, long time and many seas away, I learned about electrons moving within organic molecules based on electromeric and inductive effect. Googling them today, I found that they are ...
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1answer
565 views

Which hydrogen of 3-methylcyclohex-2-en-1-one is the least acidic?

Which hydrogen of 3-methylcyclohex-2-en-1-one is the least acidic? According to me it should be 2, as on its removal there won't be any resonance stabilization as would happen in the other ...
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Why is +M effect of OH greater than OR?

In some books it is written that +M (mesomeric effect) effect of OH is less than that of OR . The reason they give is inductive effect of R (group) which sounds senseful . But at some places it is ...
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How are the hybrid orbitals of sulfur hexafluoride shaped?

On the fluorine end the fluoride atoms are simply completing a $3p$ orbital. On the sulfur end one could posit a hybrid of one $3s$ orbital, two $3p$ orbitals and a three inner $2p$ orbitals. However,...
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217 views

Can atoms delocalize in molecules?

Electrons can delocalize over multiple equally probable bonding structures. Can atoms delocalize over multiple equally probably bonding structures in certain cases? It seems to me that any such ...
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Paracetamol: does oxygen participate in the delocalization of p-orbitals

I'm analyzing the molecular structure of paracetamol and one of the things I have to do is to make a commentary about the delocalization of p-orbitals in this compound. Well I know that in the cyclic ...
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1answer
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How many resonating structures of Carbon Monoxide are there?

Anywhere I look, I get 3 resonating structures for CO molecule, like in this answer. However, according to the rules stated for drawing resonating structures in this site, I wonder why there can't be ...
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If I can't draw resonance structures for a pi system, does that mean it doesn't exist?

Whilst trying to answer this question I came across an interesting situation regarding the relationship between resonance structures and molecular orbitals. There are two places that you can ...
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4answers
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What is resonance, and are resonance structures real?

My teacher told me about resonance and explained it as different structures which are flipping back and forth and that we only observe a sort of average structure. How does this work? Why do the ...
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3answers
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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.
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Does benzene structure stand for a single resonance form or the whole molecule?

It is known that benzene has two main resonance forms Often we still draw benzene molecule as one of them My question is, actually when we draw the lower figure, do we refer to the whole benzene ...
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758 views

Acidic strength of organic acids. Substituted PhCOOH acids

Could someone please explain the order of acidity of ortho, para and meta substituted benzoic acids with the substituent as methyl group? Methyl group operates +I and +R effect, I believe.
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N-O bonds in Nitric acid

The wikipedia article on nitric acid mentions the following structure of $\ce{HNO3}$ in which the two $\ce{N-O}$ bonds (other than that of $\ce{N-OH}$) are of different length i.e., $119.9\,\pu{pm}$ ...

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