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 not 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? What is the hydride 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 product results from the endo approach of the hydride source?

d) which product would you obtain if you would use NaBD₄ and CH₃OD instead of NaBH₄ and H₂O?

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.

4. The procedure in the reader requires 200 mg of sodium borohydride to reduce 200 mg of camphor. Student A uses 0.135g of camphor for his reaction.

a. How much sodium borohydride does he need for his reaction (assuming that he uses the same ratios like in the original procedure)?

b. What else does he have to change?

c. Which reagent is used in excess in this reaction? By how much (factor) and why?

5. Why is it necessary to clamp the filter flask during the vacuum filtration and use a neoprene adapter? Which filter paper should be used for a Hirsch funnel?

6. A student reacts 2-butanol with conc. sulfuric acid at 130 C. After an aqueous work-up, she distills the mixture and obtains a GC-chromatogram of the distillate using a polar column.

a. The GC print-out shows three peaks total at 3 min, 3.2 min and 6 min. Which conclusion can be made about the composition of the mixture?

b. How could she identify the compounds using GC chromatography?

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