1. General

Review the following topics: IR spectroscopy, polarimetry

Don't forget to start writing your formal report. By now, you should be able to write an introduction that contains an alternate synthesis for the aldehyde and chiral epoxides.

2. Experiment

a. Jacobsen ligand

The potassium carbonate has to be dissolved first before the aldehyde is added. This is very important to avoid side reactions.

You should use your own aldehyde if possible. If you did not get a crystals by now, check the residue using IR spectroscopy. If your oil contains significant amounts of the ladehyde, just use it as it is and use a little more of it in order to ensure that you have enough aldehyde present to get the ligand.

Make sure that you set the temperature to a gentle reflux and do not forget to stir it.

A reflux period of 30-45 minutes is usually sufficient in order to complete the reaction. Most of the time, a yellow precipitate is formed in the beginning already.

During the drying step, make sure that the washing procedure followed correctly: first water, then saturated sodium chloride solution and last the drying agent in the organic layer only (try to remove the aqueous layer as good as possible). We will use a rotavap to remove the solvent.

For procedure how to use the polarimeter see last page of reader and link.

3. Thing to think about

a. Why do you add water to the reaction mixture before you allow it to cool down?

b. How many signals do you expect to see in the ¹³C-NMR spectrum of the ligand?

c. How does the polarimetric measurement help to establish the absolute configuration and purity of the ligand?