Meeting 3 Problem Set - 30BL

Announcements

1. NO ONLINE QUIZ FOR THIS MEETING!

2. The IR assignment for this quarter is due on August 21, 2009 at 5:00 pm in YH 3077E. No late assignments will be accepted. Assignments cannot be submitted via email, fax, etc.

Homework questions for meeting 3 (all of them are part of the prelab!)

1.Using PC Spartan 2002 at the Science Learning Center (4th Floor Young Hall) do the following:

a. Draw camphor if you have not done it yet (Make sure that all hydrogen atoms are still attached!). 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. Which isomer is expected to be the major product for this reaction? Why? (Include the LUMO diagram generated in question 1 to answer this question. Make sure to show the proper orientation! Hint: What are you trying to show here?)

b. What would change if NaBD₄ and CH₃OH/H₂O were used in this reaction? Show the structure of the product.

c. What would change if LiBH(n-Bu)₃ was used in the reaction?

d. Why is the LUMO orbital used to rationalize the stereochemistry in this reaction?

3. Referring to the below reaction,

answer the following questions:

a. Draw the products formed in this reaction

b. Which product is the major and which is the minor? Explain using the LUMO generated above (Include the LUMO diagrams generated in question 1 to answer this question. Make sure to show the proper orientation!). What are the differences compared to 2-norboranone?

4. Experimental

a. Why is diethyl ether a poor choice as solvent for the reaction?

b. What would be the driving force for the reaction if sodium borohydride was used as reducing reagent?

c. The procedure asks to heat the mixture gently. Why?

d. After the reaction is completed, the reaction mixture is chilled and water is added. Which purpose does this step serve?

e. The amount of drying agent used here should be minimized. Explain why. How does the student know that he added enough?

f. Why is the diethyl ether removed using a warm water bath?

g. A student observes a melting point of 202-208 ^oC for his final product in this reaction. Which conclusion(s) can he draw?