Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: tangent1.57 on August 08, 2009, 10:59:21 PM
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Why are double-bonds electrophilic when, in fact, there are a lot of electrons in that area? C=C should be electro-phobic!
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They generally behave as nucleophiles.
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C=C bonds undergo ELECTROPHILIC ADDITION reactions because there is a pie-electron cloud surrounding the sigma bonded C-C. This makes the attack of an electrophile easier. Further as the C-atoms are sp2 hybridised, so, their electronegativity increases compared to sp3. Hence they behave as nucleophiles
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if you draw the resonance structure of C=C, you get C+-C- (ie one C with a positive charge and the other negative)..obviously the atoms would rarely exist like this for any amounts of time...however this still shows the nucleophilic nature of the carbon....
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C=C bonds undergo ELECTROPHILIC ADDITION reactions because there is a pie-electron cloud surrounding the sigma bonded C-C. This makes the attack of an electrophile easier. Further as the C-atoms are sp2 hybridised, so, their electronegativity increases compared to sp3. Hence they behave as nucleophiles
in fact there is an empty π* (LUMO) which is easily filled and the π-bond is breaking.
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there is an empty pie* (LUMO),not n* , easily filled and the pie-bond is breaking
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MAYBE there is an empty pie* (LUMO),not n* , easily filled and the pie-bond is breaking