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Meeting #13
General Announcements
1. The next quiz will be administered on Wednesday November 16, 2005 at 12 pm. It will cover electrophilic substitutions and drying of solvents.
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.
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. why is it important to dry the benzoic acid thoroughly prior using it in this step?
b. which function does the sulfuric acid have in this reaction?
c. why is water added after the reaction mixture cooled to room temperature?
d. why is sodium bicarbonate used in the work-up process? Show pertinent equations.
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. 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. hydroxy group
b. chloro
c. amide bonded via the nitrogen atom
d. tert.-butyl