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 (4/7/2016 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

Due to its high flammabilty, diethyl ether, like all other solvents, is removed using a rotary evaporator. This will be the first time for most of you using this piece of equipment. It can be a little intimidating at first, so make sure to watch the video very carefully and read the appropriate tutorial to be prepared when you come to the lab. The online quiz is there to enforce this preparation and reduce accidents that are due to improper usage. Since all solvents will be removed using the rotary evaporator in Chem 30BL, it is in your own best interest that you learn as quickly as possible to use this piece of equipment efficiently.

In the initial stage of the experiment, a setting of 1-2 on the hotplate will usually provide enough heat for a gentle boiling of the reaction mixture. Please keep in mind that methanol has a low boiling points (~65 ^oC) and that 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?

The drying reagent should be used sparingly. A larger excess will make it unnecessarily difficult to separate the liquid and the solid phase later and will also lead to a loss of 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.

For the polarimetric analysis, the exact concentration of the solution 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. The polarimetry cell cannot have any air bubbles in the cell. Any bubbles in the path will act as a barrier and cause problems in the measurement (i.e., dark sample error, unstable readings, etc.).

3. Critical Thinking Questions

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