1. General Comments

For those of you who were wait-listed, the class should show up on your study schedule by Friday. The class is IMPACTED. Please keep in mind that the instructor has the right to refuse signing the drop form. Many students think that this is just a formality, but in reality the signature confirms that the instructor agrees with the student that it would be best to drop the course due to a hardship. The instructor will not sign any drop forms after meeting 8. No exceptions!

Make sure that you read up on how to use the FTIR instrument (FTIR). The TA will demonstrate its operation during the lab section. You should have read the procedure already and be able to ask specific questions about things that are not clear to you before you attend to your lab section. Please make sure that you understand how to use equipment properly without breaking it.

Try to make yourself familiar with the electronic resources that are given to you on the course web site. It will save you a lot of work in the library in terms of finding physical properties and safety related data.

By now, you should have purchased a lab notebook (if you don't have one left from 30AL), a cotton lab coat, goggles and nitrile gloves before you enter the second lab. You can purchase them from the medical bookstore or AXE (YH1275, note: they only except credit cards and have very limited business hours!). You will not be allowed to perform any work in the lab if you are not appropriately dressed. No exceptions!

It would probably be beneficial to read the IR chapter in the reader as well. This will make it easier for you to understand the IR part in the lectures to come. Aside of that, you will have to work on the IR assignment very soon as well.

2. Experiment

Safety note: Concentrated sulfuric acid and concentrated phosphoric acid are both very corrosive and possess a high density. Sulfuric acid causes severe burns on your skin and clothes. A piece of paper turns black due to the acid's dehydrating (=water absorbing) property. A lot of organic compounds are incompatible with concentrated H₂SO₄, hence react pretty violent upon contact.

If the cyclohexanol solidifies in the syringe, do not panic. Just warm the syringe and needle gently until it melts.

It is very difficult to give any specific setting for the hotplate, because every hotplate has a slightly different heat output. The temperature of the hotplate should be as high as it is necessary to distill a milky mixture ( = cyclohexene + water) over slowly (~30 minutes). A wet paper towel should be wrapped around the Hickman head and the air condenser to cool the glassware (Hint : The wet paper towel can be secured using the test tube clamp). However, excessive wrapping should be avoided (you are not preparing a mummy!), because the experimenter has to be able to observe what is going on inside the setup i.e. if the product collects in the Hickman head. Due to the heat radiation of the hotplate, the glassware will warm up quickly and the product will not condense anymore if it is not properly cooled.

The final product is fairly volatile (b.p.= 83 ^oC). The storage vial has to be capped right away after the product is transferred from the Hickman head. It might be a good idea to store it in an ice bath to minimize the loss due to evaporation.

The top of the air condenser should not be closed with a cap or a septum, because this most likely result in an explosion and an automatic "F"-grade for the course!

Only a small amount of anhydrous sodium sulfate should be added to the organic layer only (see chapter out about drying agents). This will make it easier to separate the liquid and the solid later on.

And finally, nothing should be discarded before the final product has been isolated and positively identified by IR spectroscopy, melting point, etc.

3. Critical Thinking

a. What would happen if the temperature was set too high during the first distillation? What distills over during the first distillation?
b. What remains behind in the vial after the first distillation?
c. What is the function of the saturated sodium chloride solution in the work-up?
d. What is the proper arrangement of the spin vane in the conical vial? Explain briefly.
e. Why does the sodium sulfate have to be removed before you distill the crude product again?
f. Why should the experimenter not distill to dryness in the second distillation?
g. A student isolates a clear liquid after the second distillation. Can he conclude that his experiment was sucessful?
h. What is the function of the 1,2-dimethoxyethane in the KMnO₄ test?