Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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)

2
votes
1answer
17 views

Are the C-C bond lengths different in 2-methyl propene

When we were first taught resonance it was with the example of benzene and I myself justified it by thinking that the double bond oscillates because no two carbon atoms are special and hence there is ...
-1
votes
0answers
22 views

Stability and Resonance [duplicate]

The linked answers do attempt to clarify on 'stability' but I wanted an answer with specific connection to resonance. For example, the ethanoate ion can exist in many forms but, as we know from data,...
-1
votes
0answers
10 views

How To Decide Hyperconjugative (+H,-H), Resonance (+R,-R) And Inductive (+I,-I) Effect Of Any Group Relative To Any Other Group [on hold]

I WAS SOLVING A COUPLE OF QUESTIONS ON ACIDIC AND BASIC BEHAVIOR FROM AN ORGANIC CHEMISTRY BOOK AND WAS FACING DIFFICULTY SOLVING SOME QUESTIONS BASED ON THE AFORESAID CONCEPT. I WOULD REALLY BE ...
-1
votes
0answers
37 views

Arrange the following in increasing order of contribution to resonance hybrid [on hold]

Arrange the following in the increasing order of their stability $$ \underset{\text{(I)}}{\ce{CH2=\overset{+}{N}=\overset{-}{N}}} \quad \underset{\text{(II)}}{\ce{\overset{+}{C}H2-N=\overset{-}{...
-1
votes
1answer
41 views

Why (SO4)^2- does not create 4 double bonds

I looked this question up and still couldn't understand. Why, in $\ce{SO4^2-}$ don't the 4 oxygens create double bonds. In that case the all the oxygens will have 0 formal charge while the sulfur ...
-2
votes
0answers
13 views

Predict the relative energies of following resonating structures [closed]

I am not able to solve this question. Plz help
0
votes
0answers
12 views

What are the total amount of resonance structures for these two cations and which is the most stable cation?

Please see the following two cations. I have proposed the following resonance structures. Please let me know if I have missed something. Thank you.
-1
votes
0answers
36 views

Definition of conjugation and Dewar resonance energy [closed]

What is a precise definition of conjugation in organic molecules? Why, for instance, do we say a molecule like 1,3-butadiene is conjugated? A valence bond picture might argue the opposite, since ...
2
votes
1answer
36 views

Does hyperconjugation into sigma-star explain methylamine's increased basicity relative to ammonia?

The inductive effect with the polarisation of the C-N bond obviously plays a role in stabilising the positive charge of the conjugate acid. But given the similar electronegativities for C and H, CH3 ...
-1
votes
0answers
20 views

Which one is more stable? Keto or enol form?

The image shows the structure of the compound in consideration. I am confused if the enol form is stabler due to aromatic ring presence or the keto form due to extended conjugation. Also the enol form ...
-2
votes
1answer
59 views

Stability order of carbocations [duplicate]

These are some of the most stable carbocations, but what is the relative stability order between them. According to me it should be: C>D>B>A........ I came to this conclusion because both C and D ...
0
votes
2answers
89 views

Why does delocalization lead to stability? [duplicate]

If the electrons are relatively more stable when they are delocalized than when they are localized between two atoms, then why do we have bonds formed in the first place? Forming of bonds between two ...
0
votes
1answer
46 views

Compare stability of the given carbocation

Give the order of stability of the given carbocations. Usually stability is determined by studying effects taking place in the carbocation. All are resonating and there is no diff in inductive effect....
-2
votes
1answer
93 views

Which Carbocation is most stable among the three? [closed]

According to me the answer should be (C) as that Carbocation will be stablized by resonance with Chlorine. I have read that resonance is the biggest deciding factor about the stability of a ...
1
vote
0answers
36 views

Basicity of nitrogen in amide versus basicity of nitrogen in aniline

I was wondering that how can we compare the basicity of nitrogen in amide to the nitrogen in aniline as in both structures the lone pair on nitrogen is in conjugation as shown below, Can someone help ...
1
vote
2answers
103 views

Determining the more acidic proton in cyclopenta-1,3-diene

I am in the David Klein textbook in Chapter 3 going over rule 2 of finding the more acidic proton: if the electron pair in the conjugated base is delocalized, then the conjugate base is more stable, ...
13
votes
2answers
533 views

Do non-classical carbanions exist?

There are some non-classical carbocations, such as the 2-norbornyl cation, in which the positive charge is heavily delocalised. Have non-classical carbanions also been discovered? I have not seen any ...
2
votes
0answers
81 views

Sigma electron movement in resonance forms

I have come across an example in my textbook, which shows resonance structures for the bromonium ion. However, I am confused as to why the sigma bond electrons "move" to get the tertiary carbocation ...
1
vote
1answer
163 views

Which has more enol content?

According to me, resonance in {a} is more effective than {b}. And for monocyclic ketones, enol has very less content. I say {1} has lesser enol than {2}. Which is right?
0
votes
0answers
85 views

Which is most stable resonance structure of 4-nitrophenoxide ion?

According to my coaching module the first structure is more stable. Why is this so? I feel both must be approximately equally stable since negative charge is on oxygen in both cases. Would someone ...
-1
votes
2answers
39 views

Resonance in benzene: creation of current

I am a student. I recently studied resonance in Benzene. I know that π electrons in Benzene are involved in resonance this means the electrons somewhat move in the process of resonance. I have a ...
-1
votes
1answer
241 views

How does hyperconjugation explain the stability of alkenes?

The more the number of alpha hydrogens, the higher is the stability of alkenes, because the more the number of hyperconjugative structures. Why is this so? Has it got something to do with the ...
0
votes
0answers
182 views

Tautomerism in phenyl substituted compounds

Why doea phenyl substituted compounds have more enol content? For example, in almost all benzyl glyoxals and diarylmethanes, the enol content range up to a 100% I tried to see the effect of ...
-1
votes
1answer
71 views

Resonance structure and stability

Does the existence of resonance structures always translate as stability? I've been taught that resonance structures generally "spread out" charge in order to compensate for deficiency or excess of ...
-1
votes
1answer
53 views

Stability order of methy benzyl cations?

I know that meta position shown no resonance effect and hyperconjugation effect . So According to the order given I guess Hyperconjugating effect is taken into account as -CH3 has no Resonance effects....
0
votes
1answer
172 views

Are the following structures aromatic?

I have not seen this type of question anywhere so I do not know the answer. This is just a problem that has been roaming around in my head that I may have seen somewhere. My approach - Since ...
5
votes
1answer
252 views

What is the most stable structure amongst the keto-enol tautomers of pentane-2,4-dione?

I was assigned the following question and I cannot decide which is the correct answer. Which is the most stable structure? (a) pentane-2,4-dione (b) 4-hydroxypent-4-en-2-one (c) (Z)-4-...
1
vote
0answers
90 views

Is steric inhibition of resonance, or of protonation, dominant in 0-substituted anilines?

There's a question about inhibition of resonance: Is steric inhibition of resonance or steric inhibition of protonation dominant in o-toluidine? If you look at Martin's answer he says that CH3 is ...
1
vote
3answers
2k views

Why do electron donating groups decrease the acidity of aromatic carboxylic acids?

If we look at the resonance structures of benzoate anion, we would see that some amount of positive charge is present on the ring and this charge can get delocalised on the ring, like this: Now, if ...
-1
votes
1answer
305 views

Is ortho-nitro benzoic acid more acidic than formic acid?

We know that the Electron Donating effect of the benzene ring in benzoic acid makes it less acidic than formic acid! And we also now that whenever an ortho substituent is present in benzoic acid ...
-1
votes
1answer
58 views

Is delocalisation of non-bonding electrons into the benzene ring possible in case of conjugate base of benzoic acid? [duplicate]

If we take a look at conjugate base of benzoic acid it is as given below: Now my question is: Is delocalisation of non bonding electrons(in the carboxylate part) into the benzene ring possible? ...
0
votes
1answer
42 views

How far-reaching is the effect of conjugation?

Due to conjugation, it is possible for 1,4-addition, or conjugate addition, to occur. I was thinking, since conjugation and resonance effects do no diminish with distance, unlike inductive effects, ...
9
votes
1answer
102 views

Electrophilic aromatic substitution of napthalene

It is known that the $\alpha$-position (or 1-position) for napthalene is the preferable position for substitution to occur at. However, I am getting two different explanations as to why this is the ...
1
vote
1answer
589 views

Why carbonyl groups are strong benzene deactivating group for electrophillic aromatic substitution?

In carbonyl group there is a resonance avaibility and also due to inductive effect it can also withdraw electron from benzene ring . As, resonance(e- donating chracter) dominates than Inductive effect ...
4
votes
2answers
561 views

How does the 1.5 bond order of ozone contribute to its instability?

I'm confused as to why ozone is so unstable? I've been told it's because it has a fractional bond order. However, this doesn't make sense to me. Don't fractional bond orders mean resonance and doesn't ...
6
votes
2answers
200 views

Why do most carboxylic acids have high pKa (~5) in spite of having a conjugate base ion that is stabilized by resonance?

This is from my textbook: Carboxylic acids owe their acidity ($\mathrm pK_\mathrm a$ of about $5$) to the resonance-stabilized carboxylate anions formed by deprotonation. Why are they such weak ...
-1
votes
1answer
51 views

Why can't negative charge on a carbon have resonance with a neighboring alcohol?

In these resonance forms of a conjugate base of ascorbic acid, why can't the electrons on the negatively charged carbon in the third form be used to form a double bond with the alcohol and thus ...
0
votes
0answers
97 views

Resonance structures for acyl imidazole

I was asked to draw the four resonance structures of the acyl imidazole boxed in the picture. I'm not too confident with drawing resonance structures, so i'm really not sure if the answer i came up ...
3
votes
0answers
1k views

How to calculate the resonance energy of thiophene?

How to calculate the Resonance energy of Thiophene? I know how to calculate the resonance energy of Benzene. I am applying same procedure for thiophene, too. (Wikipedia: Resonance energy) The values ...
0
votes
1answer
125 views

Why do the unsaturated ketones have C-O bond weaker than saturated ketones? How it is related to resonance structures?

I am studying Infrared Spectroscopy and the book says that unsaturated ketones have a carbonyl group which has weaker bond because it's more single-bond character than single bond because it has these ...
0
votes
2answers
2k views

How many resonance structures does the oxalate ion have?

I have drawn the Lewis structure of the oxalate ion, and I see that two oxygens are double bonded to the carbons. When finding the resonance structures, I said there are 2, but the exam solutions ...
9
votes
2answers
1k views

Participation of Pi-bonds and lone pairs in resonance

Below is a quote from Klein's Organic Chemistry 3rd edition: Here is the bottom line: Whenever an atom possesses both a π bond and a lone pair, they will not both participate in resonance However, ...
9
votes
1answer
542 views

How does conjugation affect reactivity?

From this topic on MOs of butadiene vs ethene, it is clear that when two ethene molecules are combined to extend the conjugate chain, the HOMO is raised in energy and the LUMO is lowered in energy. ...
3
votes
1answer
2k views

Is an antiaromatic compound more stable than a non-aromatic compound because of more conjugation?

(image from a LibreTexts page (archive link)) It is shown that the antiaromatic compound is more stable than the non aromatic compounds 2 and 3 because of a more conjugated system. Here's the exact ...
4
votes
1answer
169 views

Is planarity really necessary for conjugation?

If we look at the $\ce{ClO4-}$ anion, the chlorine atom in it is sp3 hybridised. Hence, it has a tetrahedral structure in which conjugation shouldn't be possible, but while explaining the acidic ...
1
vote
0answers
47 views

Do amides oxidize to double-bonds?

Do amides from primary or secondary amines ever oxidize to a double-bond on the nitrogen? For example, like from an $\mathrm{R \bbox[yellow]{\color{red}{-}}(NH)-(C=O)-R'}$ to an $\mathrm{ R \bbox[...
9
votes
1answer
2k views

Most basic nitrogen in Adenine

I need to find the most basic site of Adenine: The $\ce{NH2}$ group and $\ce{NH}$ cant be strong base as electrons are delocalised. This leaves us with $1,7,3$. I thought that electron density on $1,...
2
votes
0answers
119 views

Is Argus lab accurate?

I was trying to calculate the resonance energy of benzene by using Argus Lab. These values are weird and very different from the experimental data. I have two questions regarding them. What is the ...
0
votes
1answer
278 views

Comparison of acidic strength between nitric acid and nitrous acid

These are the structures of nitric acid and nitrous acid respectively: To compare acid strength, we compare the stability of the corresponding conjugate base. Here conjugate bases are nitrate and ...
5
votes
2answers
3k views

What is the most “important” resonance structure of SCN⁻?

Numerous online references say that $\ce{SCN-}$ has two resonance structures: I am wondering why this structure is not also possible? I expect structure 3 to be rare because of the high formal ...