1. General

If you were wait listed or added to the class, you should make sure that you are enrolled by the end of the week (4/10/2015 at 12 pm). If not, please inform the instructor asap. You will not receive credit for the course, if you are not on the roster when it comes to assigning grades. Due to the fact that you will not be insured if an accident happens in the lab, you will be dismissed from the course immediately.

2. Experiment

Diethyl ether is removed using a rotary evaporator. This will be the first time for you to use this piece of equipment in Chem 30BL course. Make sure to watch the video very carefully and read the appropriate tutorial so that you have some idea how this works and what the safety precautions are. The online quiz is there to enforce this preparation and avoid any accidents due to improper usage. Since all solvents will be removed using the rotary evaporator in Chem 30BL, it is in your own interest that you learn as quickly as possible to use this piece of equipment.

In the initial stage of the experiment, a setting of 1-2 on the hotplate will provide enough heat for a gentle boiling of the reaction mixture. You do not want to evaporate the entire methanol. Why? Make sure to place a watch glass with some ice on the top during the reaction. Why?

Do not add too much of the drying reagent to the ether solution. It will make it unnecessarily difficult to separate the liquid and the solid phase later. You will lose a significant amount of your product as well. Why?

The sodium borohydride bottle has to be closed after removing the amount of NaBH₄ needed. Why?

Gas chromatography is a very sensitive technique. Check on the web site for details (GC). Dissolve only ~1-2 mg of your final product in 1 mL of diethyl ether. If you use significantly more, the column will be overloaded and all following sample runs will be difficult because the background signal increases. Make sure that you label your vial and write down the bar code number before you give it to your TA. The printout can (usually) be picked up in YH 3077E in the afternoon of the following day.

The exact concentration of the solution that is used for the polarimetry has to be known ( in w/v) in order to be able to determine the specific optical rotation of the sample. This will allow for the determination of the ratio of (-)-isoborneol and (+)-borneol assuming that the components are strictly additive.

It is important that the polarimetry cell is properly filled, which means that there can be no air bubbles in the cell.


3. Critical Thinking

a. How can you distinguish between camphor and isoborneol using infrared spectroscopy?
b. Why is often a fairly broad melting point observe for the final product?
c. Why do you get a mixture of isoborneol and borneol?
d. How can you distinguish between borneol and isoborneol?
e. Why does the infrared spectrum of borneol look very different when acquired in solid or the gas phase?
f. Assuming the student uses L-(-)-camphor for the reaction, which products would he isolate in the end? How could you prove that?
g. How could one increase the diastereoselectivity of the reaction in the lab?
h. How do the infrared spectra of borneol in solid form and in the gas phase differ from each other? Why do they differ?