last updatedThursday, November 01, 2007
Problem set Meeting 12 Announcement
1. The instructor will offer an in-lab demonstration of the Grignard setup on November 5, 2007 at 4:00 pm and 4:30 pm in YH 6086. You will get 5 points to attend this meeting.
2. The final version of the paper is due on November 9, 2007 at 5 pm in YH 3077E in printed version (submission via email will not be accepted). Late reports will get 10% of per day late. Make sure that you turn it in online by November 12, 2007 at 10 pm.
3. The next quiz (=quiz 5) will be administered on November 7, 2007 at 10 am. 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.
Questions
1. Referring to the Grignard reaction, answer the following questions. Show chemical equations when appropriate.
a. Why is it important to exclude water as much as possible during the formation of the Grignard reagent? How is this accomplished?
b. Which observations will the experimenter make upon initiation of the reaction?
c. Why should the bromobenzene not be added in neat form?
d. What would be the consequences if the ethereal bromobenzene solution was added too slowly or too quickly?
e. During the workup, 10% sulfuric acid is added to the reaction mixture. Explain.
f. Why is the organic layer extracted with sodium hydroxide solution?
g. How does the final product look like?
2. Theoretical issues
a. Why is it easier to form Grignard reagents from are iodides than from fluorides?
b. Diethylether is a commonly used solvents for Grignard reagents. Explain briefly.
c. Assuming you wanted to prepare a Grignard reagent of a fairly unreactive alkyl chloride, how could you accomplish this task?
d. Why is the ipso carbon in PhMgBr considered a nucleophile while it is an electrophile in PhBr?