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Nucleophilicity and basicity

  1. Oct 26, 2009 #1
    I have read that basicity is compared by equlibrium and nucleophilicity by kinetics , then how do we compare basicity with nucleophilicity ??
    That is if there is a negatively charged molecule and H+ and a carbocation , how do we come to know which will be attacked by the negatively charged molecule ?
     
  2. jcsd
  3. Oct 27, 2009 #2

    chemisttree

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    You should realize that nucleophilicity does not require a negatively charged molecule. Neither does a base. If we were to have a base and a nucleophile present with a carbocation and a proton, the base would most likely react with the proton most rapidly. Nothing imposes any restriction on the approach of the proton to the base since the bare proton's reactive face is 'omnidirectional'. The reactive side of the base is likely localized to a particular location on one side or the other of that molecule, so the approach of the proton to the base must occur from one side of the base only. A nucleophile (it can be negatively charged) has the same requirement as a base but since no information is given (in your question) as to it's shape or charge distribution, nothing can be said about its rate of reaction.

    In the example of the carbocation and nucleophile (even negatively charged ones), both faces of the reactants must line up and approach each other in a particular fashion and with a particular energy. This imposes somewhat of a limitation on the degrees of freedom allowed for the reaction to proceed to completion resulting in a slower reaction rate.

    The upshot is that protonation is much faster than either SN1 or SN2 type reactions.
     
  4. Oct 29, 2009 #3
    what is the criteria that weather a given reaction is sn1 or sn2?
     
  5. Oct 29, 2009 #4
    how can we determine the product of an organic compound according to the catalyst,reagent...that are given in the reaction process?
     
  6. Oct 31, 2009 #5
    One thing to think about is that equilibrium is the point where the forward reaction rate is equal to the reverse reaction rate. With equilibrium you are concerned about the energy difference between reactants and products, but in a kinetics problem you're more concerned with the energy difference between the reactants and the activated state.
     
  7. Oct 31, 2009 #6
    Yes ! that is exactly what my question is !
     
  8. Nov 2, 2009 #7
    how can we determine the product of an organic compound according to the catalyst,reagent...that are given in the reaction process?
     
  9. Nov 4, 2009 #8
    Hi,

    This is what my question is all about and i really wnt to know this as, somewhere I am getting confused in this question and I will clear it out while let just want to know about this.


    Thanks!
     
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