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.

Filter by
Sorted by
Tagged with
1
vote
0answers
182 views

Determination of the most acidic hydrogen in an organic compound

Identify the most acidic hydrogen in the compound below: Can someone please explain why is $\ce{H^\mathrm{a}}$ in the compound below more acidic than $\ce{H^\mathrm{b}}$? This is what is written in ...
0
votes
0answers
61 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,...
4
votes
1answer
288 views

Which of the two structures is more stable?

Which of the two structures is more stable? As far as I know, alkenes with a greater number of hyperconjugating structures are more stable. Hyperconjugation has a greater stabilizing effect than ...
3
votes
0answers
168 views

Chugaev and Selenoxide Elimination giving different products

In class we are going over intramolecular elimination. In this question I will provide two similar reactants that provide a different mixture of products. The chugaev elimination gives a 50/50 ...
1
vote
0answers
166 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.
3
votes
1answer
404 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 ...
16
votes
5answers
3k views

Define, (actually define) the "stability" and "energy" of a compound

When we say a conformer or compound is of "higher energy" than another, are we quantifying energy in terms of the bond strength? Or are we going off of how much energy it takes to break the bond? I ...
-1
votes
2answers
2k views

Stability of alkadienes

Which of the following is the most stable? (i) Conjugated alkadiene $(\ce{CH2=CH-CH=CH2})$ (ii) Isolated alkadiene $(\ce{CH2=CH-CH2-CH=CH2})$ (iii) Cumulated alkadiene $(\ce{CH2=C=CH2})$ (iv) All are ...
0
votes
0answers
68 views

Why benzene has more heat of hydrogenation than cyclohexene? [duplicate]

According to me, benzene is more stable than cyclohexene due to its aromatic nature. Therefore the heat of hydrogenation of cyclohexene should be more than benzene (because I read that heat of ...
5
votes
0answers
207 views

Stability of carbocation

While comparing the stability, as the $\ce{CH3}$ group is electron donating, the first structure should be more stable due to this reason. But apparently the second one is more stable. Is there ...
2
votes
1answer
861 views

Why is Acetic acid (pKa = 4.76) stronger than carbonic acid (pKa = 6.36)? [duplicate]

In order to try and understand this, I evaluated it via stability of conjugate bases. The acetate vs carbonate ion. The only difference is what's attached to the carboxyl group, the $\ce{-CH3}$ and ...
2
votes
0answers
494 views

Stability of methoxy-methyl and tropylium carbocations

Which is expected to be more stable: methoxy-methyl carbocation $(\ce{CH3-O-CH2+})$ or tropylium $(\ce{C7H7+})$ cation? I think because oxygen would donate its lone pair so there will be complete ...
-2
votes
1answer
1k 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 ...
-1
votes
2answers
440 views

Perpendicular orbitals in aryl and vinyl carbocations? [duplicate]

This point (iv) has been given under reasons for extremely low reactivity of aryl and vinyl halides. I cannot understand it. First of all, isn't the positive carbon atom in phenyl as well as vinyl ...
1
vote
2answers
633 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 ...
4
votes
3answers
2k views

How does hyperconjugation lead to stability?

I know that hyperconjugation leads to delocalization of electrons between filled and unfilled orbitals and thus greater stability (that's what most textbooks said). However, I think that it reduces ...
-1
votes
1answer
690 views

Why is a carbon to iodine pi-bond less stable than a carbon to fluorine pi-bond?

This question comes from a second semester undergraduate organic chemistry course. Please refer to the image below with regard to the question. My understanding of the trend in section 4a is that "...
1
vote
1answer
1k views

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 ...
-2
votes
1answer
1k 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 ...
0
votes
1answer
633 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?
0
votes
1answer
100 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 ...
0
votes
1answer
123 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 ...
3
votes
0answers
578 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 ...
0
votes
1answer
627 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, ...
3
votes
3answers
662 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
votes
1answer
1k views

Stability comparison on the basis of violation of Bredt's rule between bicyclic carbocations

Compare stability between the two bicyclic compounds. Both compounds I and II seem to be unstable because of violation of Bredt’s rule: they are sp2-hybridized. Then how to compare the stability ...
3
votes
1answer
2k 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{...
-1
votes
1answer
273 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 ...
2
votes
0answers
2k 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. ...
2
votes
1answer
1k 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 ...
3
votes
1answer
167 views

Ring Expansion 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 has to be stabilised by ring expansions. The other 2 are my predicted structure so please ...
2
votes
2answers
4k 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-...
7
votes
1answer
7k 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
votes
1answer
756 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
votes
1answer
3k 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
votes
2answers
177 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. ...
2
votes
2answers
469 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 ...
2
votes
1answer
786 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 ...
7
votes
0answers
577 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 ...
1
vote
1answer
1k 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 ...
-2
votes
2answers
153 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 ...
10
votes
2answers
1k 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 ...
0
votes
1answer
212 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 ...
18
votes
2answers
7k 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 ...
0
votes
1answer
1k 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 ...
6
votes
4answers
3k 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?...
2
votes
2answers
1k 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 ...
1
vote
0answers
277 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 ...
-3
votes
1answer
901 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 $\pu{363 °C}$ ...
8
votes
2answers
2k 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 ...

1 2 3
4
5
10