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Meeting #13
General Announcements
1. The next quiz (=quiz 5) will be administered on February 19, 2008 at 12 pm. It will cover the Grignard reaction and the esterification. Make sure that you show up on time. Otherwise you will not be allowed to take the quiz.
2. Please look start looking for a partner for the last project. Your partner should be in a different time slot than yourself e.g. if you are in T/R morning section, your partner should be in section in the T/R afternoon section or in the W/F afternoon section. The proposal will be due on February 29, 2008 at 5 pm .
3. If possible both reactions (esterification and nitration) should be carried out in this lab. 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, 2008. Late submission will not receive any credit.
4. Ideally, the esterification and the nitration are carried out in the second meeting. This will give you more time to
Homework questions (...those can only be answered correctly by students that were not sleeping in lecture :-))
1. Referring to the Esterification carried out in the lab, answer the following questions. Show chemical equations where appropriate.
a. One point that was stressed in lecture is the absence of water. How is this accomplished here?
b. A student wonders why he has to add sulfuric acid to the reaction mixture even though one of his starting materials is an acid. Explain.
c. Methanol has two functions in this reaction. Explain.
d. The procedure asks to cool the reaction mixture is first and then poured it into water. Why is the cooling imperative and and why is the mixture poured into water in the first place here?
e. Why is the organic layer extracted with sodium bicarbonate? How does the student know that he is done with this step?
f. What does the final product look like?
2. Referring to the Nitration reaction carried out in the lab, answer the following questions. Show chemical equations where appropriate.
a. Why is it important that the ester is dissolved in sulfuric acid first? Show the appropriate intermediate.
b. Another thing that was stressed in lecture was the temperature control during this reaction. Why is this important and how is this accomplished?
c. How is the electrophile in this reaction obtained?
d. Why is the reaction mixture poured onto ice and not straight into water?
e. The student then attempts to recrystallize the crude product from water:methanol, (4:1). What would he observe?