Questions tagged [carbocation]
Carbocations are species bearing a positive charge on carbon. They are intermediates generally formed during organic reactions, which can be stabilised by various electronic effects. Less stable carbocations are capable of undergoing rearrangements to form more stable carbocations in the course of a reaction.
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Why is 1‐tert‐butylcyclopentan‐1‐ylium more stable than 1‐(2‐methylbutan‐2‐yl)cyclopentan‐1‐ylium?
(1) should be more stable as the $\ce{CH3}$ group is electron donating.
But apparently (2) is more stable.
Is there another phenomenon taking place here?
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How do we check octet rule in resonance structures?
For example, this carbon has an incomplete octet:
Can we say this is because C has configuration $\mathrm{1s^2 2s^2 2p^2}$ and hence here its just forming 3 bonds whereas it should form 4 to make it $...
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Determining the stereochemistry of the product(s) when an alkyl shift in a carbocation generates a chiral carbon
Consider this carbocation:
We know that this carbocation would immediately rearrange - by a methyl shift - to form the more stable carbocation.
Now, notice that the migration will produce a chiral ...
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If alkyl-substituted alkenes are more stable, how does one explain their increased addition reactivity?
My understanding is that in alkyl-substituted alkenes there is hyperconjugation between $𝜎(\ce{C−X})$ and $𝜋^∗(\ce{C=C})$. I also have read that more alkyl-substituted alkenes are many folds more ...
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Stability of the alkenyl and phenyl cations
One reason often cited for why alkenyl and phenyl halides do not undergo nucleophilic substitution by the $\ce {S_N1}$ mechanism is that the formation of the alkenyl and phenyl cations involve a ...
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Major product of isomerization reaction
I am trying to come up with a logical mechanism for the following transformation, where 2-methylenecyclobutan-1-ol is converted to cyclopentanone under acidic conditions:
What I have tried to do was ...
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Carbon atoms which carbocation and carboanion are BOTH less stable then arene/vinyl
I'm trying to come up with a compound class in which iodine atom would be a bad leaving group both whether it leaves or takes charge with it (I know that $\ce{I^+}$ on its own would be horrible ...
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Nucleophilic Substitution rate comparison 1-bromobutane and 2-bromo-2-methylpropane with NaOH
I want to ask a question about the hydrolysis of haloalkanes to form alcohols.
I have been presented with a flowchart diagram of possible reactions of haloalkanes below:
Now, I have been presented ...
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Nucleophile substitution in nonclassical carbocation
In nucleophilic substitution of exo-2-norbornyl brosylate, carbocation formation is the rate determining step and the carbocation formed is: (in equilibrium)
After forming carbocation, the ...
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Resonance structures of 4‐aminobut‐3‐en‐2‐ylium
Problem
How many resonance structures can be drawn for the following molecule?
(a) 1
(b) 4
(c) 3
(d) 2
Answer
Question
I think that the molecule can be drawn in three ways, which contradicts the ...
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Is this rearrangement in carbocation possible?
Generally, in the following type of reactions, positive charge on $\alpha$-Carbon causes ring expansion, but in the following example positive charge is formed on $\beta$-Carbon and the cation is ...
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Relation between formation of carbocation and availability of nucleophile
Many sources suggest that in SN1 reactions the leaving group first exits the molecule, and the resulting carbocation is subsequently attacked by the nucleophile, suggesting that there is no relation ...
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How ring expansion is possible here?
Recently I have came across this question.
I went with the 3rd option as ring expansion cannot occur due to the formed stable 3 degree carbocation. But the answer key claims 4th option. How can ...
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Which 1,2-methylene shift is more favourable in ring expansions where ring has substituents
In the above reaction, first the -OH group is protonated after which it leaves creating a carbocation intermediate as shown
Now, ring expansion is a more favourable rearrangement, however there is a ...
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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 ...
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