last updated Thursday, February 12, 2009

Meeting #12

General Announcements

1. The next quiz (=quiz 5) will be administered on February 18, 2009 at 8 am and will cover steps 3 of the Lidocaine project and the Grignard reaction. 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 i.e. 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 for the independent project will be due on February 27, 2007 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 February 20, 2009. Late submission will not receive any credit. Sorry! :-(

Homework questions

1. Referring to the Esterification carried out in the lab, answer the following questions. Show chemical equations and intermediates where appropriate.

a. What is the function of methanol in this reaction? How much is used?

b. What is the function of the sulfuric acid in this reaction?

c. After the reflux, the procedure asks to cool the reaction mixture first and then poured it into water. What is the purpose of this step?

d. Why are the combined the organic layers extracted with sodium bicarbonate? How does the student know that he is done with this step?

e. How 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. What is the function of the concentrated sulfuric acid here? Show the appropriate intermediate.

b. The temperature has to be well controlled during the reaction. Why is this important and how is this accomplished?

c. Why is the mixture poured onto ice and not into water after the reaction is completed?

d. The crude product is recrystallized. Which solvent is used and how does the final product look like?

e. What are the major changes in the IR spectrum going from methyl benzoate to the product of the nitration reaction?