last updated Thursday, November 03, 2005

Problem set  Meeting 12 

Announcement

The instructor will offer an in-lab demonstration of the Grignard setup on Monday November 7, 2005 at 4 pm in YH6086.

The Grignard reaction will be started on Tuesday, November 8, 2005.

There will be no lab meeting on Thursday, November 10, 2005. However, keep in mind that this is the due date for the formal report.

Questions

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

a. The glassware has to be dried very thoroughly before running the reaction. How is this done and why?

b. Why is it necessary to crush the Mg-turnings before placing them in the round-bottomed flask?

c. Why is it important to add the bromobenzene/diethyl ether solution slowly during the reaction?

d. Why is sulfuric acid added during the work-up? Show pertinent chemical equations.

e. What is the difference between "chipped ice" and and "crushed dry-ice"?

2. Why are ethers most commonly used as solvents for Grignard reactions?

3. Why are bromides most often used as starting materials to form Grignard reagents?

4. Predict the products of 3-Bromocyclohexanone with

a. Methyl Grignard

b. Lithium dimethylcuprate(I)

c. Ethylene/Tetrakis(triphenylphosphine)palladium(0)

after the work-up.