last updated Tuesday, February 14, 2006

Problem set  Meeting 12 

Announcement

The instructor will offer an in-lab demonstration of the Grignard setup on Wednesday February 15, 2006 at 4:30 pm in YH6086.

The final version of the paper is due on February 17, 2006 at 5 pm in YH3077E. Make sure that you turn it in online by February 19, 2006 at 10 pm.

Questions

1. Referring to the Grignard reaction, answer the following questions.

a. The procedure asks to minimize the amount of water present in the system. Why is this important and how is this accomplished?

b. Like most metals magnesium is covered by an oxide layer on the surface. Why is this a problem and how this problem be solved?

c. How can the reaction be initiated if it does not start upon addition of the bromobenzene solution?

d. The bromobenzene/diethyl ether solution is added slowly during the reaction. Why?

e. Before adding the sulfuric acid during the work-up, "chipped ice" is added. Why?

2. Why are ethers most commonly used as solvents for Grignard reactions. Explain briefly. Which problems does the experimenter face when using ethers?

3. Why are alkyl bromides more reactive than aryl bromides?