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12 Apr 2008 01:11:03 IST
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What Actually is Hyper Conjugation ? URGENT
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This is very URGENT guys. I was cruising through the Plus One textbook today when I found this little bit really confusing. I remember procrastinating over learning this last year. So, I don't have the time to go through the whole of the shit in the text.
WHAT IS HYPER-CONJUGATION ?
Please GIVE ME AN ANSWER AS IF I'M JUST STARTING OUT. It'll help me understand faster. I wasn't able to find any useful info on the web. Useful links are also appreciated.
PLEASE............. RATES ASSURED !!!!
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aNdRoMeDa
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Joined: 10 Sep 2007
Posts: 1319
12 Apr 2008 01:16:17 IST
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hyperconjugation
is also knw as no bond
itz observed wen d alpha carbon has hydrogen atoms .....
d type of elctron relese by alkyl group attached 2 d unsturated group is caleld hyperconjugation
d hydrogen atom carrieds d positiev charge bt tere is no bond betwn d hydrogen and d carbon atom
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12 Apr 2008 01:18:17 IST
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Hyperconjugation is the stabilising interaction that results from the interaction of the electrons in a s-bond (usually C-H or C-C) with an adjacent empty (or partially filled) p-orbital or a p-orbital to give an extended molecular orbital that increases the stability of the system.
Based on the valence bond model of bonding, hyperconjugation is described as "double bond - no bond resonance" but it is not what l resonance,
Hyperconjugation is a factor in explaining why increasing the number of alkyl substituents on a carbocation or radical centre leads to an increase in stability.
consider methyl group involved in hyperconjugation with a carbocation centre.
the empty p orbital associated with the positive charge at the carbocation centre is in the same plane (i.e. coplanar) with one of the C-H s-bonds
This geometry means the electrons in the s-bond can be stabilised by an interaction with the empty p-orbital of the carbocation centre.
The stabilisation arises because the orbital interaction leads to the electrons being in a lower energy orbital
the C-C s-bond is free to rotate, and as it does so, each of the C-H s-bonds in turn undergoes the stabilising interaction.
So the ethyl cation has 3 C-H s-bonds that can be involved in hyperconjugation.
The more hyperconjuagtion there is, the greater the stabilisation of the system.
for example, the t-butyl cation has 9 C-H s-bonds that can be involved in hyperconjugation. Hence (CH3)3C+ is more stable than CH3CH2+
The effect is not limited to C-H s-bonds, appropriate C-C s-bonds can also be involved in hyperconjugation.
all above is what i searched from net
Based on the valence bond model of bonding, hyperconjugation is described as "double bond - no bond resonance" but it is not what l resonance,
Hyperconjugation is a factor in explaining why increasing the number of alkyl substituents on a carbocation or radical centre leads to an increase in stability.
consider methyl group involved in hyperconjugation with a carbocation centre.
the empty p orbital associated with the positive charge at the carbocation centre is in the same plane (i.e. coplanar) with one of the C-H s-bonds
This geometry means the electrons in the s-bond can be stabilised by an interaction with the empty p-orbital of the carbocation centre.
The stabilisation arises because the orbital interaction leads to the electrons being in a lower energy orbital
the C-C s-bond is free to rotate, and as it does so, each of the C-H s-bonds in turn undergoes the stabilising interaction.
So the ethyl cation has 3 C-H s-bonds that can be involved in hyperconjugation.
The more hyperconjuagtion there is, the greater the stabilisation of the system.
for example, the t-butyl cation has 9 C-H s-bonds that can be involved in hyperconjugation. Hence (CH3)3C+ is more stable than CH3CH2+
The effect is not limited to C-H s-bonds, appropriate C-C s-bonds can also be involved in hyperconjugation.
all above is what i searched from net
12 Apr 2008 17:30:15 IST
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Hyperconjugation is the stabilising interaction that results from the interaction of the electrons in a s-bond (usually C-H or C-C) with an adjacent empty (or partially filled) p-orbital or a p-orbital to give an extended molecular orbital that increases the stability of the system.
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