Questions tagged [stability]

Applied to a chemical species, the term expresses a thermodynamic property in reference to a standard, stating that one state is lower in energy than another. The tag should be applied to questions seeking answers with respect to the stability (or instability) of a certain chemical species, molecular entity and/or electronic structure. It must not be applied to questions about the reactivity of particular chemical species.

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46 views

Is it correct to say that benzene is more stable than cylcohexatriene due to delocalization?

I'm virtually all chemistry books I own say that benzene is more stable than the theoretical cyclohexatriene, by 150 kJ to be specific, due to the delocalization of pi electron density around the ring....
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Energy of reactants and products [closed]

In some reactions, energy is released and when I want to understand the reason for the release of energy, I find that the energy of the products is lower than that of the reactants. But What is this ...
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Why are sulfoxides usually stable as ylides (S charged positively and O negatively)? What's the BDE for S-O?

I can't find any info on BDE for singularly bonded S to oxygen. Moreover, I'd like to understand, why is it quite usual to find sulfoxides structure written with charge separation?
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confusion regarding meta-cresol and phenol

when I googled the answer, i found out that m-cresol has a PKa value of 10.1 whereas phenol has 10.0. I am simply unable to use any logic to compare their strengths. We have been taught only the ...
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2answers
65 views

Why is this compound more basic than the other?

So, the original question was which compound is more basic. Compound A and Compound B respectively. My reasoning is that on protonation, Compound B would be more stable than Compound A as well, ...
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64 views

Reduction of nitrobenzen using LiAlH4 [closed]

Can you please explain why isn't nitrobenzene reduced to aniline but turns out as azobenzene on reaction with LiAlH4? Please explain the mechanism.
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63 views

What is the relation between strength of a base and the thermal stability of its salts?

In Concise Inorganic Chemistry, $5^{th}$ edition, by JD Lee, while discussing oxides and hydroxides of Group $2$ metals, it has been stated that: The increase in basic strength is illustrated by the ...
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65 views

Why is the rate of solvolysis of t-butyl chloride lesser than that of 1-chloro-1-methylcyclohexane?

I came across a question regarding relative rate of solvolysis. According to the answer key: My analysis: As in all the three cases, the Cl atom is bounded to a tertiary carbon, hence, all of them ...
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33 views

Is bond dissociation enthalpy same for homolytic and heterolytic cleavage? [duplicate]

In David R Klein's Organic Chemistry Book, Chapter of Radicals, one of the 'skillbuilder' questions is to identify the weakest C-H bond in the following molecule: The solution was to split each ...
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27 views

First ionization energy and electron gain enthalpy of dihydrogen / stability comparison of dihydrogen ions [duplicate]

Subset of: How can antibonding orbitals be more antibonding than bonding orbitals are bonding? Stability of $\ce{H2^{-}}<\ce{H2^{+}}<\ce{H2}$ Stability of $\ce{N2^{-}}<\ce{N2^{+}}<\ce{N2}...
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Why is salicylic acid less acidic than o- anisic acid? [duplicate]

The Pka of salicylic acid is 2.97 while that of o-anisic acid is 3.73. Why is the latter less acidic if the order of +M effect states that -OH>-OR which should make the conjugate base less stable?
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Why does a methyl shift occur during the pinacol-pinacolone rearrangement?

Why does a methyl shift occur during the pinacol-pinacolone rearrangement? I was told that methyl shift is done to stabilise the carbocation but here we are shifting the ...
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Why is ethanol more acidic than acetone?

The acidity of a compound is determined by the stability of its conjugate base and the major structure of enolate has a negative charge on the Oxygen atom. Moreover, the negative charge on the O-atom ...
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Why and how does ring expansion occur in the dehydration of (cyclobut-3-ene-1,2-diyl)dimethanol?

Can someone explain how does this ring expansion occur with the mechanism? I do understand that the hydride shift occurred because of carbocation stability but why did the ring expand? Can you please ...
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Effect of distance on the mesomeric effect

I have always thought that mesomeric effect is somewhat dependent on distance. But I recently came across a question where I was asked to predict the order of stability of o-methoxyphenyl carbocation ...
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Why is PbI₄ not composed of lead(II), iodide and triiodide?

$\ce{Pb^4+}$ is reduced by $\ce{I-},$ so $\ce{PbI4}$ cannot exist with $\ce{Pb}$ in $+4$ oxidation state. But if I replace three $\ce{I-}$ with $\ce{I3-},$ then we can have $\ce{Pb^2+}$ similar to $\...
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45 views

Carbocation formation and stability from bromo compounds

When heated,the following bromo-species all form carbocations via $\sigma$ bond cleavage. For each structure draw the corresponding carbocation and briefly describe how it is stabilised. This is my ...
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Preferred radical attack on a polyester

My question concerns the relative stability of a radical next to an ester oxygen compared to a radical next to an ester carbonyl carbon. The stabilizing effect of the electron pairs of ether oxygen ...
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1answer
45 views

What exactly is the idea of gaining stability by the various chemical species?

When we consider the alkaline metals for example, we say that an atom of a metal like sodium gains stability by losing an electron, however this doesn't seem to be a very meaningful statement. Either ...
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148 views

Keto-enol tautomerism in a bicyclo compound

Question Which one is more stable- the keto or enol form. The compound given is this: Solution The enol form would violate Bredt's Rule and would therefore be unstable. Hence the keto form is more ...
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1answer
54 views

Acidic character and anion stability across periods and groups of the periodic table [duplicate]

I understand that to compare relative acidity one must consider the stability of the conjugate bases. Across a period the electronegativity of an element increases. And that is for example why $\ce{HF}...
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1answer
172 views

Stability of complexes based on number of rings [duplicate]

$\ce{[Co(edta)]^-}$ has 5 rings in total and in $\ce{[Co(en)_3]^{3+}}$, there are 3 rings. The stability of the former is more than that of the latter. The reason I was told was that a complex with ...
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165 views

Yield of alkyl chloride in the Hunsdiecker reaction

Apparently the yield of alkyl chlorides is low as compared to that of alkyl bromides when preparing alkyl halides using the Hunsdiecker reaction. Why does this occur? The only factor I can see is the ...
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Regarding stability and reactivity of m-xylene

I came across the following two details about m-xylene: m-Xylene is thermodynamically most stable compound among o-xylene, m-xylene, and p-xylene. m-Xylene is most reactive towards nitration and ...
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On the stabler tautomer in amide-imidic acid tautomerism

In the section on acid-catalysed hydrolysis of nitriles, this webpage has the following line of reasoning; ...the more stable amide tautomer predominates the (following) equilibrium. (credit) How ...
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Is there an enolate equivalent for enamines?

I'm learning that enolates are stronger than enamines are stronger than enols in terms of general nucleophilicity. Makes sense. But what I can't find any explanation for online is why the trend ...
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89 views

Stability in 3-4 membered conjugated ring [closed]

We have 3 products one is cyclobuta-1,2 diene cyclobuta-1,3 diene and the other is cyclo prop-2-en-one, we want to find the stable product out of the 3. So,the third one due to high angle strain, ...
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79 views

Among Benzyl carbocation (Ph-CH2+) and Methyl methoxy carbocation (CH3-O-CH2+), why is the latter more stable?

Benzyl Carbocation could form multiple conjugation, then why isn't that stabler? In Methyl methoxy carbocation, Oxygen donates the lone pairs but so does the double bond in the benzyl Carbocation.
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Stabilization of multiple bonds through inductive effects

In the conversion of m-chloroanisole to m-anisidine using $\ce{NaNH2}$ and liquid $\ce{NH3}$, apparently the reason the $\ce{NH2-}$ goes for the meta- position instead of the para position is that, in ...
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312 views

How to compare stability between 5‐methylcyclohexa‐1,3‐diene and 3‐methylenecyclohexene?

Problem Compare stability of 1 and 2: Answer My approach Both have the same number of π-bonds. Both have one resonance structure. Both are non-aromatic. In 1 there are three α-hydrogens, whereas ...
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81 views

Choosing hyperconjugation when resonance doesn't give a reason for stability

Which of the following structures would be least stable? I initially approached it like this: As both are allylic carbocations, and that both are in fact resonating structures of the same molecule, ...
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1answer
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Second-step activation energy in SN1 reactions

In SN1 reactions, it's known that there are generally two steps, with the first being the R.D.S step involving carbocation formation and the next having a lower activation energy. Why does the second ...
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92 views

Why is the molozonide adduct thermally unstable?

In the mechanism of alkene-ozonolysis, the intermediate molozonide adduct, which is a cyclical but symmetric molecule (shouldn't symmetry about the C-C single bond bring stability?), decomposes ...
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1answer
43 views

Which of the following compounds possess more than one percent enol content? [closed]

Which of the following compounds possess more than one percent enol content? I understood that stability of enols are dependent on the hydrogen bonding in the compounds. But here, what is the ...
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2answers
216 views

Stability of Carbanions

For comparing stability of carbanion, we use the fact that "negative charge is stable on more electronegative atom." So, The stability order is, {electronegative order: $\mathrm{sp \gt sp^2 \...
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Stabillity of ethyl, iso propyl and vinyl free radicals

Well this might seem like a dumb question but I was just wondering if any other factor would apply here as well? By simply looking at the number of hyperconjugative structures, I could easily tell ...
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How would we arrange these in the increasing order of stability? [duplicate]

Here we have three isomers of butene there structure of who I have attached: cis-butene trans-butene iso-butene I was able to figure out that the trans isomer would obviously be more stable than the ...
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1answer
586 views

How is Gibbs free energy related to stability? [closed]

I have been learning thermodynamics for quite some time and I fail to relate Gibbs free energy and stability. For example, how do I compare stability of metal oxides using the following data? Also, do ...
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What is the definition of thermodynamic stability?

The term thermodynamic stability is used on this site, but I can't find a good definition. Is is a quantitative or a qualitative concept? Does it apply to a single compound, or a pair of compounds? ...
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Why is oxygen more stable than oxygen dication?

According to molecular orbital theory (MOT), $\ce{O2^2+}$ has a greater bond order than $\ce{O2}$ and two less antibonding electrons. So why is molecular oxygen $\ce{O2}$ more stable than the ...
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How to decide the order of stability of allylic carbocations when comparing to benzylic carbocation?

I was going through my organic notes and found this order of stability of carbocation: 3° benzylic > 2° benzylic > 2° allylic > 3° alkyl I understand that all this is explained on the basis ...
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Acidity order in substituted Phenylboric acid

Here, we are asked to find the acidity order. For the first one, the answer given is ii > i > iii (c) and for the second one, it is iii > ii > i (b). Any logic that I think for one of ...
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Priority of the stabilising factors of resonating structures of Organic compounds

When finding the stability order of resonationg structures of certain molecules.. there is some confusion since some structures satisfy certain factors and others satisfy certain other factors. I want ...
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Is N--O--N known to exist?

Commonly, the empirical formula $\ce{N2O}$ refers to the molecule with structure $\ce{N\bond{~--}N\bond{~-}O}$. Is the isomer $\ce{N-O-N}$ known to exist? I'm guessing it is significantly less stable ...
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Deciding which group twists out of the plane when ortho effect takes place

I'm going to take a few stills from 3D conformers of the following compounds available on PubChem in which ortho effect is applicable to show what I'm referring to. 2-Nitrobenzoic acid: N,N-Dimethyl-...
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Which is more reactive in E1, benzyl or allyl

I'm don't know the english terminology for chemistry so sorry for probably butchering some terms. My question is, which of these is more reactive in an E1 reaction: The bottom two are the ...
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1answer
367 views

How can I know which molecule is more stable when bond order it's equal?

So, I was wondering, I have these molecules $\ce{O^+2}$, $\ce{O^-2}$, $\ce{O2}$ and $\ce{C^+2}$. When I try to find their bond order and their magnetic nature I get this: $\ce{O^+2} = \frac{1}{2} \...
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1answer
72 views

Stability of pyridine derivatives

Arrange the following pyridine derivatives in the order of increasing stability of adduct formed with $\ce{BBr3}.$ Explain briefly. I'm pretty confused about which structure is the most stable. I'd ...
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1answer
400 views

Performing an SN1 reaction in a polar aprotic solvent

Straightforward question What would be the outcome of having an SN1 reaction carried out in a polar aprotic solvent? I have found this question approached scarcely and with unsatisfactory answers. ...
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53 views

Why isn't just a fully occupied valence s orbital stable?

Why arent elements like calcium with an electron configuration of $[\text{noble gas}]\ n\mathrm{s}^2$ stable, although all the populated orbitals are fuully filled? Why is it necessary to obtain an ...

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