1. General

Review the following topics: extraction

You will need to check out a set of glassware from the lab support. Upon receipt, check for cracks in the glassware, if the stopper and stopcocks fit and if the kit is complete. You will hold responsible for breakage and lost equipment. Clean the glassware when you are done and return it to the lab support at the end of the session!

Start your literature search for the formal report!

Read and understand the guidelines for the formal report.

It might be good to read the following paper: Orchin, M., J.Chem.Ed. 1989, 66, 586.

2. Experiment

Safety note: Diethyl ether is highly flammable.

For the Grignard setup and hints how to start the reaction follow the link. Make yourself familar with the setup and the observations in order to be able to repeat it in the laboratory. It is highly recommended to draw a sketch of the seetup in yortu lab notebook. The Grignard reaction will take a significant amount of time, because there are a lot of little things that can go wrong.

Do not connect more than two heat guns to one fume hood. Be aware that they are very hot after you used them. Place then noozle pointing up in the back of the fume hood to allow cooling.

Use the grease on the ground glass joints lightly. A thin film at the top part of the joint will be enough to get a good seal. The joints will become clear when you turn the them against each other.

It is a good idea to scratch some of the magnesium turnings with a spatula to have a fresh surface for the reaction. This will the reaction to initiate better.

To prepare the bromobenzene solution either mix the bromobenzene and the ether in a beaker and then pour the solution into the additional funnel or the ether into the additional funnel first, add the bromobenzene and then mix well with a glass rod. Do not pour the bromobenzene in first and then the ether. Why? Close the anhydrous ether can when you took the amount out that you need!

To initiate the reaction, add only 5-8 mL (not more!) of the solution to the magnesium turnings. If necessary heat the solution gently. Have an ice bath handy, in case the reaction gets out of control. Once the reaction started, add the rest of the solution so that the mixture keeps boiling

Never let the reaction die down. PhMgBr is not very soluble in diethyl ether. It will precipitate and cover the magnesium surface. Why does this mean a problem?

Crushed ice is not dry ice!

NEVER, EVER THROW A LAYER AWAY AS LONG AS YOU ARE NOT SURE THAT YOU ISOLATED YOUR FINAL PRODUCT!

3. Things to think about

a. Student A is running late and decides to add the bromobenzene solution faster than asked for in the procedure. In the end, he only isolates a small amount of benzoic acid. How can you explain the poor yield?

b. What will be the final product (after acid work-up) when you react PhMgBr with esters, ketones, nitriles, or carbon disulfide (CS₂)?