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Why Benzyl carbocation more stable than phenylethyl carbocation?
Wiki User
∙ 14y ago
Stabilization of a carbocation can also be accomplished by reasonance. If the cationic carbon is adjacent to an unsaturated system, the positive charge can be delocalized over adjacent atoms resulting in greater stability of the carbocation. Thus, the carbocations showing resonance are far more stable than those in which the resonance is not flesible.
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∙ 12y ago
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Is it possible for all reactions which have a carbocation intermediate to undergo rearrangement reaction to get a more stable cation?
No, in general
Comparison of stability of 1 2- benzylethene and 1- benzylethene?
Benzyl ethene is not a proper name it means 3-phenyl propene similarly 1,2 dibenzyl ethene means 1,4 diphenyl -2- butene, the later is more stable due to possibilities of more resonating structures.
Why tertiary alcohol is more reactive?
Tertiary alcohols are also bonded to three other carbon atoms (whereas secondary alcohols are bonded to two, primary alcohols to one). These other carbon atoms share their electronegative charges with the middle carbon.
Why do you get isopropyl benzene on treating benzene with 1 - chloropropane instead of n - propyl benzene?
Your question is in regard to the "Friedel-Crafts Alkylation" reaction, which is probably the most common way to add an alkyl group to a benzene ring. The reaction is carried out with benzene or a substituted benzene, an alkyl chloride or bromide, and a small amount of a Lewis acid catalyst; usually either FeCl3 or AlCl3 when an alkyl chloride is the reagent, or FeBr3 or AlBr3 when an alkyl bromide is the reagent.The first step in the reaction forms a carbocation when the halide on the alkyl group is removed by the Lewis acid. If 1-chloropropane is used, the first step of the reaction is:H3C-CH2-CH2Cl + FeCl3 ''Ä¢√á H3C-CH2-C+H2 + Fe{Cl}4-Primary carbocations are the least stable ones after the methyl carbocation, therefore they will almost always rearrange if possible to yield a secondary or sometimes even a tertiary carbocation. Thus, the next thing to occur is formation of a secondary carbocation. This happens when a hydrogen atom on the middle carbon migrates to the carbon bearing the positive charge and brings two electrons with it. This is called a hydride shift because the hydride ion is H-, and it takes place as shown:H H| '¬ß¬µ |H3C-CH-C+H2 ''Ä¢√á H3C-C+-CH3(I apologize, but these were the best graphics I could do given the tools available here.) The equilibrium shown is in much greater favor of the secondary carbocation, however I would not be surprised if some propyl benzene is formed.So, there are two parts to the answer to your question: 1) A primary carbocation is formed when a 1-chloro-n-alkane reacts with a strong Lewis acid. 2) Because the reaction of a carbocation with benzene is slower than formation of the primary carbocation, the primary carbocation has time to undergo a hydride shift, thereby creating a much higher concentration of the more stable isopropyl carbocation.P.S.: Have you studied which groups activate a benzene ring and which groups deactivate the ring, and which groups direct subsequently added groups to the meta position and which groups direct groups later added to the ortho and para positions? If you have, what compound would you expect to be the major product of the reaction? What can one do practically speaking when performing the reaction above to minimize multiple alkylations?I'm correcting two molecular drawings included in the original posting. They did not come out anywhere close to how they appeared on the screen when I wrote the first answer.The first one didn't come out that badly:+H3C-CH2-CH3 -----> H3C-CH2-CH2 + Fe(Cl)4-.The second graphic was a drawing of the secondary (isopropyl) carbocation:+H3C-CH-CH3. (The "+" symbol is normally drawn much closer to the atom bearing the formal positive charge. It was not possible to do this here as answers rarely require graphics.)
What is a more stable atom between lithium and gold?
Gold is more stable.
Why tertiary carbocation is more stable?
due to hypercongugation
Is it possible for all reactions which have a carbocation intermediate to undergo rearrangement reaction to get a more stable cation?
No, in general
Why would aryloxiranes be especially sensitive to low pH?
All epoxides are sensitive to low pH as they are susceptible to hydrolytic cleavage by H+ ions. An aryloxirane, basically an epoxide attached to an aromatic ring, is more sensitive to low pH because if the epoxide ring is broken, it will form a benzylic carbocation which is much more stable than the primary carbocation that would form from the hydrolyic cleavage of a long chain epoxide. Draw the mechanism for the hydrolytic cleavage of 2-phenyloxyrane and it should become clear.
Comparison of stability of 1 2- benzylethene and 1- benzylethene?
Benzyl ethene is not a proper name it means 3-phenyl propene similarly 1,2 dibenzyl ethene means 1,4 diphenyl -2- butene, the later is more stable due to possibilities of more resonating structures.
How might pea agar inhibit both gram negative and gram positive?
By containing more than 25% phenylethyl alcohol.
Why is cyclopropyl methyl cation more stable than tpm cation?
the case of cyclopropylalkyl cation and substituted cyclopropyl cations is interesting. Cyclopropylmethyl cation has been found to be more stable than benzyl cation and the stability increases with each addition of cyclopropyl groups. This increased stability has been explained between the bent orbitals of cyclopropyl rings and the vacant p orbital of the cation carbon. The vacant p orbital lies parallel to C2-C3 bond of the cyclopropane ring and not perpendicular to it. Thus the geometry becomes similar to that of a cyclopropane ring conjugated with an olefinic bond.
Why tropylium ion is more stable than triphenyl carbocation?
as because in case of tropylium cation extra stability arises from the attainment of aromaticity as well as extensive conjugation.It contains 6π electrons which is according to Huckel's rule indicate towards the aromatic compound as well as the system is also a resonance stabilized because of delocalisation
When atoms combine to form compound do they become more stable or less stable?
More stable
Why tertiary alcohol is more reactive?
Tertiary alcohols are also bonded to three other carbon atoms (whereas secondary alcohols are bonded to two, primary alcohols to one). These other carbon atoms share their electronegative charges with the middle carbon.
Why do you get isopropyl benzene on treating benzene with 1 - chloropropane instead of n - propyl benzene?
Your question is in regard to the "Friedel-Crafts Alkylation" reaction, which is probably the most common way to add an alkyl group to a benzene ring. The reaction is carried out with benzene or a substituted benzene, an alkyl chloride or bromide, and a small amount of a Lewis acid catalyst; usually either FeCl3 or AlCl3 when an alkyl chloride is the reagent, or FeBr3 or AlBr3 when an alkyl bromide is the reagent.The first step in the reaction forms a carbocation when the halide on the alkyl group is removed by the Lewis acid. If 1-chloropropane is used, the first step of the reaction is:H3C-CH2-CH2Cl + FeCl3 ''Ä¢√á H3C-CH2-C+H2 + Fe{Cl}4-Primary carbocations are the least stable ones after the methyl carbocation, therefore they will almost always rearrange if possible to yield a secondary or sometimes even a tertiary carbocation. Thus, the next thing to occur is formation of a secondary carbocation. This happens when a hydrogen atom on the middle carbon migrates to the carbon bearing the positive charge and brings two electrons with it. This is called a hydride shift because the hydride ion is H-, and it takes place as shown:H H| '¬ß¬µ |H3C-CH-C+H2 ''Ä¢√á H3C-C+-CH3(I apologize, but these were the best graphics I could do given the tools available here.) The equilibrium shown is in much greater favor of the secondary carbocation, however I would not be surprised if some propyl benzene is formed.So, there are two parts to the answer to your question: 1) A primary carbocation is formed when a 1-chloro-n-alkane reacts with a strong Lewis acid. 2) Because the reaction of a carbocation with benzene is slower than formation of the primary carbocation, the primary carbocation has time to undergo a hydride shift, thereby creating a much higher concentration of the more stable isopropyl carbocation.P.S.: Have you studied which groups activate a benzene ring and which groups deactivate the ring, and which groups direct subsequently added groups to the meta position and which groups direct groups later added to the ortho and para positions? If you have, what compound would you expect to be the major product of the reaction? What can one do practically speaking when performing the reaction above to minimize multiple alkylations?I'm correcting two molecular drawings included in the original posting. They did not come out anywhere close to how they appeared on the screen when I wrote the first answer.The first one didn't come out that badly:+H3C-CH2-CH3 -----> H3C-CH2-CH2 + Fe(Cl)4-.The second graphic was a drawing of the secondary (isopropyl) carbocation:+H3C-CH-CH3. (The "+" symbol is normally drawn much closer to the atom bearing the formal positive charge. It was not possible to do this here as answers rarely require graphics.)
Is carbon a more stable element than silicon?
Silicon is more stable.
What is a more stable atom between lithium and gold?
Gold is more stable.
