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Meeting #13
General Announcements
1. The next quiz will be administered on Thursday May 18, 2006 at 12 pm. It will cover esterification and electrophilic substitutions.
2. Please look start lookin 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 26, 2006.
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.
Homework questions
1. Referring to the esterification part of the project
a. The procedure requires that the reaction mixture is refluxed. Explain briefly why.
b. While water should be eliminated during the actually formation of the ester, water is added after the reaction mixture was cooled to room temperature. Explain.
c. The etheral layer is extracted with sodium bicarbonate during the work-up process. Explain and show pertinent equations.
d. Why is it imperative to remove the the alchohol entirely from the ester?
2. Referring to the nitration experiment, answer the following questions.
a. Which function does sulfuric acid have in this experiment? Show pertinent chemical equations.
b. Why is a careful temperature control required in this reaction? How is this accomplished?
c. A student uses a mixture of water and methanol (4:1) for the recrystallization step. What would he observe?
d. What are the most important changes in the IR spectrum going from methyl benzoate to m-nitro methylbenzoate?
3. When performing electrophilic aromatic substitution reactions, the groups that are attached to the benzene play a very important role in the reaction in terms of directing effect and rate of the reaction. Classify the following groups accordingly and explain briefly.
a. tert.-butoxy
b. iodide
c. ammonium
d. amino