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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Carbanion Stability [closed]

I was wondering that whether a Cross-Conjugated or a Extended-Conjugated carbanion is stable I have sort of memorise that a Cross-Conjugated one is more stable For example, Which of the Carbanion is ...
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1answer
524 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 ...
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1answer
396 views

Stability of formyl chloride [duplicate]

Why is formyl chloride unstable? I know it is just a combination of CO and HCl. But why it is unstable whereas other acyl chlorides are stable, like acetyl chloride?
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1answer
73 views

Stability of tertiary carbocation [duplicate]

Our teacher told us that a carbocation connected to 3 cyclopropane rings is among the most stable carbocations. But I am unable to understand how, as resonance (the most important factor governing ...
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1answer
76 views

Stability of alkene

Sorry for this silly doubt but why is CR2=CH2 alkene more stable than CHR=CHR alkene? Both have same number of alpha hydrogens. I thought that the latter is more stable as in its trans isomer, the R ...
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0answers
243 views

Could Be2- exist?

I understand that Be2 cannot exist, since it has as many electrons in the antibonding as in the bonding orbitals. But it seems to me that since the next electron would go into the πu orbital, which ...
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1answer
214 views

Thermodynamic stability and Inertness [duplicate]

The following is from my teacher's notes: The reaction (where the reaction mixture is thermodynamically unstable but kinetically inert) tends to go as indicated by a positive total entropy change, ...
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1answer
535 views

Which has more enol content? [on hold]

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?
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3answers
303 views

Is there a thermodynamic driving force for racemisation?

Why does racemisation occur? My doubts are: Is it due to entropy? If it is due to entropy, how is the reduction of optical activity by racemisation a consequence of increased thermodynamic ...
3
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1answer
959 views

According to MO theory, why is the dilithium cation more stable than the dilithium anion?

According to molecular orbital theory, $\ce{Li2}$ fills up two electrons in the $\sigma_\mathrm{g2s}$ molecular orbital; $\ce{Li2+}$ fills up one electron in the $\sigma_\mathrm{g2s}$ MO, and $\ce{...
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1answer
148 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 ...
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0answers
690 views

Comparing thermal stabilities of MgCl2 and BaCl2

I read that to compare thermal stabilities of ionic solids: if the solid has a monoatomic anion, we compare thermal stability on the basis of lattice energy which is inversely proportional to size. ...
3
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1answer
61 views

Instability due to neutrons

Why does an excess of neutrons leads to instability? For example, both $\ce{^{3}H}$ and $\ce{^{4}H}$ are unstable, with respective half-lives of $3.89\cdot 10^8$ and $1.39\cdot 10^{-22}$ seconds. ...
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208 views

Why is ninhydrin stable as a geminal diol? [duplicate]

The following image depicts the structure of ninhydrin - $\ce{C9H6O4}$ Ninhydrin, as you see has two hydroxyl group attached to same carbon. In general, geminal diol (or gem-diol, for short) are ...
2
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1answer
398 views

Why doesn't cyclopropyl methyl carbocation stabilises itself by ring expansion? [duplicate]

I have been taught that ring expansion stabilises smaller cyclic compounds to a great extent. So why does cyclopropyl methyl carbocation shows such type of resonance rather than expanding its ring ...
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1answer
78 views

Ring Expamsion And Final Structure

[If you don't like to read the question just look at the 3 pictures the first one has the carbocation which have to be stabilised by ring expansions the other 2 are my predicted structure so please ...
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2answers
2k views

Stability of geometrical isomers in cycloalkanes

Among the following, which should be the most stable compound? 1)Cis-cyclohexane-1,2-diol 2)Trans-cyclohexane-1,2-diol 3)Cis-cyclohexane-1,3-diol 4)Trans-cyclohexane-1,3-diol My thought process is-...
6
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1answer
2k views

Why can't NH5 form?

In ammonia a nitrogen atom forms 3 covalent bonds with hydrogen atoms and has one lone pair which can be used in a dative covalent bond with another hydrogen atom to form an ammonium ion. Instead of ...
13
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1answer
309 views

Stability of keto-enol vs. conjugation

I am trying to figure out which tautomer of creatinine: is more stable. We see that the enol tautomer is more highly conjugated: the $\pi$ electrons from the alcohol to the double bond to the $\pi$ ...
5
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1answer
525 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-...
9
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2answers
160 views

Are such high oxidation states as reported by Vojovodic et al. possible?

I am a student in theoretical chemistry and I am confused about the paper: Trends in adsorption of electrocatalytic water splitting intermediates on cubic $\ce{ABO3}$ oxides (Montoya, J. H.; Doyle, A. ...
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2answers
272 views

Why is dipositive dilithium more stable than neutral dilithium? [closed]

According to J.D Lee, compounds with fraction bond number are unstable. I calculated that the bond order of $\ce{Li2^2+}$ is 0.5 while that of $\ce{Li2}$ is 1. Hence, $\ce{Li2^2+}$ must be less stable ...
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1answer
324 views

Why are long oxygen chains unstable? [duplicate]

H-O-H (water), H-O-O-H (hydrogen peroxide), H-O-O-O-H, H-O-O-O-O-H, etc. This is analogous to hydrocarbon chains, methane, ethane, propane, butane, etc. Note the Hydroxygen Chains satisfy 2 covalent ...
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0answers
330 views

Bredt's rule applied to fused bicyclic systems

Ultimate question: Is Bredt's rule equally valid for fused bicyclic system (no bridgehead alkenes without a ring 8 carbons or more), but for other reasons (historical?) it is only defined as applying ...
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0answers
656 views

Compare stability of transition metal cations in aqueous solution

I have to compare the stability of the following transition metal cations: $\ce{Co^3+, Fe^3+, Cr^3+, Sc^3+}$ in aqueous solution. (Source: Joint Entrance Exam (JEE) 2013 Mains India) The first thing ...
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2answers
77 views

How two neutral atoms are together with no force between [duplicate]

How sodium atoms exist together when they all have unstability due to an extra electron present in their outermost shell? I mean how two neutral atoms Na atoms are existing together in form of white ...
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2answers
378 views

Can a six member ring expand to achieve octet completion to stabilize a carbocation?

(Probably unnecessary background: I came up with this carbocation while predicting the major product of $\ce{NaNO2/HCl}$ with 1-(methylamine)cyclohexan-1-ol) Will the following carbocation ...
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1answer
142 views

Effect of halogen atom on Markovnikov's rule

I know that the Markovnikov's rule is because of the stability of carbocations. If a halogen atom (electron-withdrawing group) is directly attached to the carbon atom carrying a positive charge, would ...
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2answers
3k views

Why is cis-1,2-dichloroethene more stable than trans-1,2-dichloroethene?

Why is cis-1,2-dichloroethene more stable than trans-1,2-dichloroethene? Usually, trans compunds are more stable than cis ones, due to less strain and its non-polarity. But, in this case it's quite ...
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1answer
681 views

Stability comparison of benzylic carbocation and benzene

Which is more stable - benzylic carbocation or benzene - and why? Benzylic carbocation may have more resonance structure, but these structures are destroying its aromaticity as well. So, how do we ...
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4answers
1k views

Why do chromyl bromide and chromyl iodide not exist?

It is known that chromyl chloride exists (popularly known as the product of a test for presence of chloride ion) but chromyl bromide and chromyl iodide are unknown. Why is it so? Why don't they exist?...
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2answers
415 views

Can an organic compound undergo ring contraction to give more stable carbocation? [duplicate]

Throughout my journey in organic chemistry I’ve only seen ring expansions by a compound in order to attain more stability, but yesterday I thought about the following reaction. I feel that ring ...
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0answers
215 views

What is the stability order for these octahydrobiphenylene structures?

According to me most stable is Z because it has maximum alpha hydrogen, Between X and Y both have same alpha hydrogen, but X has conjugation. So it is more stable than Y. So Order is Z>X>Y. Is my ...
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1answer
368 views

Why does fluorine form stable oxides while chlorine form unstable oxides? [closed]

The fluorine however it says my text book doesn't combine well with oxygen, nitrogen and itself but when about its oxides they are quite stable as $\ce{O3F2}$ has a melting point of $\pu{363 °C}$ ...
7
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2answers
862 views

Why does formaldehyde exist primarily as the gem-diol in aqueous solution?

From Wikipedia, Methanediol is the product of the hydration of formaldehyde $\ce{H2C=O}$, and predominates in water solution: the equilibrium constant being about $10^3$ and in a 5% by weight ...
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3answers
3k views

How is sulphur trioxide formed and why is it stable? [duplicate]

Structure of $\ce{SO3}$ (sulfur trioxide): In the molecule, if each oxygen atom shares two electrons with sulfur atom then how does the sulfur atom remain stable? It already has 6 valence electrons ...
4
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1answer
1k views

Rank the following radicals in order of decreasing stability

Question Rank the following radicals in order of decreasing stability Aromaticity makes a cyclic compund more stable. Here, 1 and 3 are aromatic since they follow Huckels rule(Or am I wrong ...
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0answers
54 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[...
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1answer
215 views

Why is ordinary soap and water adequate to decontaminate possible nerve agents?

In the news it was announced that anyone who might have been exposed in the recent Salisbury nerve agent incident should wash any potentially contaminated clothing as normal using regular detergent ...
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0answers
182 views

pKa of different sites of butanone

From what I can tell, deprotonation of the central hydrogen leads to the more thermodynamically stable product (most substituted double bond. i.e. most stabilization by hyperconjugation). Therefore, ...
2
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2answers
518 views

Thermodynamic stability of benzene derivatives

Q1. How can we comment on the thermodynamic stability of the following benzene derivatives? Q2. What does thermodynamic stability mean, in general? What does it mean to compare the thermodynamic ...
2
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3answers
6k views

Reactivity order of electrophilic addition

Find the order of the ease of electrophilic addition of the following: $\ce{H3C-O-CH=CH2}$ $\ce{ F-CH=CH2}$ $\ce{Cl-CH=CH2}$ $\ce{NO2-CH=CH2}$ According to me, it should be 1 > 4 > ...
4
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1answer
275 views

What drives a molecule/atom towards stability? [duplicate]

I'm very familiar with the concept that chemical reactions occur because the reactants a state of stability via the reaction. It's a very satisfying and fulfilling statement. But my question has ...
4
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2answers
1k views

Carbocation rearrangement involving three membered rings

Question: Taking into account of various carbocations and, as well as the rules governing mechanisms of carbocation rearrangements, which reaction is most likely to occur during the given reaction? ...
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1answer
95 views

Is a ring intermediate formed in hydroboration?

This was the mechanism taught to us for hydro-boration Something really strange in that mechanism is that in step 2 hydrogen has two bonds. Also , the the doubly bonded $\ce{H}$ , has one bond $\ce{...
3
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1answer
2k views

Most stable chair conformation

I am asked to draw the most stable chair conformation of compound 1. After doing so I am a little uncertain which of the conformations is the most stable. The most stable conformation is the one ...
2
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1answer
264 views

Why is mer-AlQ3 more stable than fac-Alq3?

Several research papers and books say that the meridional isomer of tris-(8-hydroxyquinoline) aluminium is thermodynamically more stable than the facial isomer. What is the reason behind this ...
13
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1answer
3k views

Thermodynamic stability of meta-xylene over ortho- and para-isomers

When talking about the example of the alkylation of toluene by chloromethane in the presence of $\ce{AlCl3}$, Hepworth, Waring and Waring (2002) mentioned that: At room temperature, a mixture of 1,...
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0answers
158 views

Reversed trends in stability of transition metal ions with respect to oxidation state

Why is titanium more stable with a lower oxidation state, but vanadium more stable with a larger oxidation state? More specifically, why is $\ce{Ti^{+}}$ more stable than $\ce{Ti^{3+}}$, but $\ce{V^{...
2
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2answers
973 views

Stability of carbanion

I am confused about how one can determine the stability of carbanions using pKa-values. I know that the stability of carbanions can be determined by the inductive effect, hybridization of the charged-...