Problem set #2 (Meeting 2)
ATTN: answers to the below questions are due at the start of meeting 2; these answers should be part of your pre-lab write-up.
1. What is the function of the sulfuric acid in this experiment?
2. What is the expected alkene product formed from the dehydration of the following alcohols? Show major products only. help
3. The reaction of cyclohexene with potassium permanganate affords 1,2-cyclohexanediol.
a. Why is 1,2-methoxyethane used in this experiment?
b. Explain briefly why the cis diol is obtained here by showing the key intermediate for the reaction.
4. The elimination reaction is an equilibrium reaction. How is the experimental yield optimize in this reaction?
5. How do you know which layer to keep during the work-up of your reaction mixture in general? Which one is it in this experiment? Explain briefly.
6. What are the most important changes in the IR spectrum going from cyclohexanol to cyclohexene (functional groups and wavenumbers)?
7. How do you know that you added enough drying agent?
8. Using PC Spartan 2002 at the Science Learning Center (4th Floor Young Hall) do the following:
a. Use the alcohols and their protonated forms (CH3CH2-OH, CH3CH2-OH2, (CH3)2CH-OH, (CH3)2CH-OH2, (CH3)3C-OH, (CH3)3C-OH2) that you drew last week for this exercise (if you don't have them, you will have to draw them at this point).
b. Select Calculations from the Setup menu.
The following window should appear. Select the options shown.
Verify that the Charge is Neutral (for -OH) or Charge is Cation (for -OH2) and Multiplicity is Singlet. Click OK.
Select Submit from Setup menu.
Then click OK to exit dialog. Close the previous window.
Select Submit from Setup menu. When the calculation is completed you will be notified. It should not take more than 2-3 minutes for the calculation to complete under normal circumstances. Make sure that you have only one window open at this point. The messages are usually displayed in the first window, and often not in the window you are working in at this point.
1. Using the distance tool, measure the distance C-O and record it.
2. Under the Display menu, select Properties. Click on the oxygen atom. A new window should appear (atom properties). Record the value for the Natural Charge. Do the same for the C-atom that has the oxygen attached.
Generate two plots (include them in your prelab):
1. The C-O bond distance as a function of the type of alcohol or carbocation (primary, seconday, tertiary) (You should have six points in your graph).
2. Do the same for the natural charge on the oxygen and carbon as a function of the carbocation.
Based on the obtained graphs, answer the following questions:
1. How does an added proton influence the C-O-bond distance in the different molecules? Rationalize the changes.
2. How does it influence the partial charges on the carbon and oxygen?
Problems: Check here