last updated
Meeting #13
General Announcements
1. The next quiz (=quiz 6) will be administered on May 15, 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 May 23, 2008 at 5 pm.
3. If possible both reactions (esterification and nitration) should be carried out during meeting 13. 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 May 16, 2008. Late submission will not receive any credit.
Homework questions
1. Referring to the Esterification carried out in the lab, answer the following questions. Show chemical equations where appropriate.
a. Why is it important that the benzoic acid dried thoroughly? How is this accomplished here?
b. A student adds hydrochloric acid to the solution of benzoic acid in methanol. What would be the consequence?
c. After the reflux, the procedure asks to cool the reaction mixture first and then poured it into water. Why is the mixture poured into water in the first place here?
d. Afterwards, the aqueous layer is extracted with diethyl ether. Why?
e. Why is the organic layer extracted with sodium bicarbonate? 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 chemical equations where appropriate.
a. Why is it important that the ester is dissolved in concentrated sulfuric acid first? Show the appropriate intermediate.
b. Another thing that was stressed in lecture was the temperature control during the reaction. Why is this important and how is this accomplished?
c. What is the electrophile in this reaction and how is it obtained?
d. Why is the mixture poured onto ice after the reaction is completed?
e. The crude product is recrystallized. Which solvent is used and how does the final product look like?