Week 3 Problem Set - 30BL

1.Using PC Spartan at the Science Learning Center (4 Floor Young Hall) do the following:

a) Draw camphor if you have nopt done it yet. Minimize the structures by clicking the minimize icon, , then save.

b) Go to the view mode by clicking the view icon, . Once in the view mode, click the Model menu and select Tube.

c) Select Calculations from the Setup menu.

The following window should appear. Select the options shown.



Verify the Charge is Neutral and Multiplicity is Singlet. Click OK.

• Select Submit from Setup menu.

  
  

  Under the Setup menu, select Surfaces. A window should appear. In this window click Add.

  

  A second window should appear. In this window, select the following

  

  Then click OK to exit dialog. Close the previous window.

  Select Submit from Setup menu. When the calculation is completed you will be notified.

  Under the Display menu, select Surfaces.

  

  A window should appear. In this window check the yellow box.

  

  Next, select the molecule by clicking on it. In the bottom right corner of the window, change the selection from Solid to Transparent.

d) Do the same (steps a-c) for 2-norbornanone.

2. Referring to the below reaction,

(endo/exo huh?)

answer the following questions:

a) for the above reduction, what is the proton source?

b) which isomer is expected to be the major product? why? (use the LUMO generated in question 1 to answer this question)

c) which isomer is expected to be the minor product? why? (use the LUMO generated in question 1 to answer this question)

d) which product results from the exo approach of the hydride source?

e) which product would you obtain if you would use LiAlD₄ instead of NaBH₄?

3. Referring to the below reaction,

answer the following questions:

a) draw the endo and exo product formed

b) which product is the major and which is the minor? Explain using the LUMO generated above.

c) which product would you obtain if you would use D₂O in the second step?

4. A student uses 0.155 g of camphor and 50 mg of sodium borohydride for his reduction.

a. Which reagent is used in excess? By how much (factor)?

b. What is the reason to use an excess of the compound in general, and in this week's reaction in specific?

5. Why is it necessary to use thick-walled tubing and a neoprene adapter for vacuum filtration?


6. What are the most important changes in the IR spectrum going from camphor to isoborneol?


7. Using the melting point diagram page 30 in your reader, answer the following questions:

a. Student A observes a melting point of 110-142 C. What can be said about the purity of compound X?

b. What is the melting point for a mixture containing 90% X and 10% Y?

c. What is the melting point and composition of the eutectic mixture of X and Y?

d. Assuming that two compounds A, B and C have identical melting points. How can you determine the identity of the compound A? Explain briefly.


8. What does the term "racemic" mean? Why do you get a racemic mixture of isoborneol in your experiment?