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8.4: Exercise Questions

  • Page ID
    470387
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    1. Using your knowledge of elimination chemistry, please indicate which solvent, water or DMSO, would you expect to better favor the E2 elimination from this exercise and why? For full credit be sure to explain your answer.
    2. Using information from your calculations or your starting materials and products please complete the following tables. Please note that the solvated value of Gibbs Free Energy is the sum of \(G\) in the gas phase, \(\Delta G_{ENP}\), \(\Delta G_{CDS}\), and \(\Delta G^{\circ}{ }_{\text {Conc }}\).
      Starting Materials
      Solvent \(G\) (Eh) Gas Phase \(\Delta G_{ENP}\) (Eh) \(\Delta G_{CDS}\) (Eh) \(\Delta G^{\circ}{ }_{\text {Conc }}\) (Eh) Solvated \(G\) (Eh)
      DMSO -693.3164 -0.083226 -0.001211 0.003012 -693.3978
      Water -693.3416     0.003012  
      Transition States
      Solvent \(G\) (Eh) Gas Phase \(\Delta G_{ENP}\) (Eh) \(\Delta G_{CDS}\) (Eh) \(\Delta G^{\circ}{ }_{\text {Conc }}\) (Eh) Solvated \(G\) (Eh)
      DMSO

      -693.3157


          0.003012
      Water -693.3291     0.003012  
      Products
      Solvent \(G\) (Eh) Gas Phase \(\Delta G_{ENP}\) (Eh) \(\Delta G_{CDS}\) (Eh) \(\Delta G^{\circ}{ }_{\text {Conc }}\) (Eh) Solvated \(G\) (Eh)
      DMSO -693.3805     0.00301  
      Water -693.3804     0.00301  
    3. To make our reaction coordinate diagram easier to interpret we will be normalizing all of our energy values to the energy of the starting materials in water. To do this, all you need to do is add the value of the Solvated Gibbs free energy (\(G\)) you are interested into the Solvated Gibbs free energy (\(G\)) of the starting materials in water. Using the values that you have documented in question 2 please complete the following tables. Please note that he conversion between energy in Hartree (Eh) and kcal/mol is 1 Eh = 627.5 kcal/mol. Hint: you will have completed this calculation correctly if the Normalized Solvated \(G\) for the starting materials in water is 0 Eh.
      Water Solvent
      Water Solvent Solvated \(G\) (Eh) (See Question 2) Normalized Solvated \(G\) (Eh) Normalized Solvated \(G\) (kcal/mol)
      Starting Materials      
      Transition State      
      Products      
      DMSO Solvent
      DMSO Solvent Solvated \(G\) (Eh) (See Question 2) Normalized Solvated \(G\) (Eh) Normalized Solvated \(G\) (kcal/mol)
      Starting Materials -693.39786    
      Transition State      
      Products      
    4. Using the thermodynamic data (in kcal/mol) please create a reaction coordinate diagram that includes a pathway for both the reaction in DMSO and in Water.
      image11.png
      Figure \(\PageIndex{1}\): Copy and Paste Caption here. (Copyright; author via source)
    5. Using your data and the reaction coordinate diagram in question 4 for support, please indicate which reaction you would expect to proceed more quickly and explain why you believe this is the case.

    This page titled 8.4: Exercise Questions is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Nicholas Boaz and Orion Pearce.