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Meeting #12
General Announcements (please read since you will held responsible for the content!)
1. Quiz 5
The next quiz will be administered on February 13, 2012 at 11 am. It will cover the entire Lidocaine project. Make sure that you show up on time. Otherwise you will not be allowed to take the quiz.
2. Research project
a. Please look start looking for a partner for the Ferrocene project. Your partner should be in a different time slot than yourself i.e., if you are in the T/R afternoon section, you will have to find somebody in the W/F afternoon section. This way nobody has to put in additional time outside their regular schedule, which means that each group has four lab meetings to complete the project. We have to avoid as much as possible to have 20+ students running around in the lab (Safety!).
b. The proposal for the project is due by March 2, 2012 at 4:30 pm. Like the Jacobsen paper, the proposal has to be submitted to turnitin.com.
3. Experimental Hints
a. It is important that the benzoic acid used is very dry and that the reaction mixture is refluxed properly during the esterification. Otherwise, the yield of the ester will be very low.
b. The nitration mixture (HNO3:H2SO4=1:1) will be provided from lab support.
c. The nitration has to be carried out at low temperatures (~0 oC). This is accomplished by using a proper ice-bath.
d. If possible both reactions (esterification and nitration) should be carried out during meeting 12. This will give you more time to recrystallize the final product and get better quality crystals. The final product has to be turned in to the TA by February 22, 2012 at 5 pm. Late submission will not receive any credit. Sorry! :-(
4. Safety
a. Concentrated nitric and concentrated sulfuric acid are very corrosive individually. The nitration mixture used in the lab is even worse. It causes major skin damage and acid burns that heal very poorly. Any direct contact with them has to be avoided.
b. Diethyl ether is removed using the rotary evaporator.
5. Report for Grignard project
The postlab report for this project is due on February 28 or February 29, 2012. The report has to be written in the lab notebook and be submitted to the TA.
Homework questions (2/16 or 2/17)
1. Referring to the esterification carried out in the lab, answer the following questions. Show balanced chemical equations and key intermediates where appropriate.
a. In lecture it was emphasized, that the benzoic acid has to be as dry as possible. How is the benzoic acid dried in the lab?
b. Methanol is used in this experiment. Which functions does it have? Explain briefly.
c. What is the function of the concentrated sulfuric acid in this reaction?
d. After the reflux is completed, the reaction mixture is cooled to room temperature and ice-cold water is added. Which purpose does this step serve?
e. Why are the combined the organic layers extracted with sodium bicarbonate solution? How does the student know that he is done with this step?
2. Referring to the nitration reaction carried out in the lab, answer the following questions. Show balanced chemical equations where appropriate.
a. The nitronium ion is the electrophile in this reaction? What is it structure? How is it obtained in the lab?
b. The nitronium ion is a strong electrophile. Which implications does this have for the reaction?
c. A student attempts to recrystallize the crude product from methanol and water (1:4). What would he observe?
d. Predict the 13C-NMR spectrum of the product.
e. What are the most important changes in the infrared spectrum going from the ester to the nitro compound?