1. General

The main goal of the experiment should be to obtain nicely shaped crystals for the diacid (final product). However, for the evaluation, the amount of crystals will also be a determining factor.


2. Experiment

It is very important that you close the CpH bottle immediately after you removed the quantity you need. Why?

Dry ice is very cold (-78 ^oC). Do not touch it with your hands. It will cause severe frost burns!

It is crucial to dissolve the maleic anhydride in ethyl acetate first before the ligroin is added. The solubility of the MA will significantly decrease in the solvent mixture. In some cases, the mixture has to be warmed up gently!

You might want to hold on to the needle when you transfer the CpH. The plastic of the syringe tends to shrink and the needle might pop off. Do not breathe the cyclopentadiene monomer (cancer suspect!).

The formation of well-shaped and big crystals takes time. If possible, try to obtain them without scratching or seeding. The less ‘seeds’ that you have in your flask, the less nucleation sites are present. It might be a good idea to allow to cover up the Erlenmeyer flask and place it in an water bath. Why?


3. Things to think about

a. What influences the ease of reaction when it comes to Diels-Alder reactions?

b. Why are Diels-Alder reactions historically important?

c. How can you distinguish between maleic anhydric anhydride and the Diels-Alder adduct using IR spectroscopy?

d. How can you distinguish between the Diels-Alder adduct and the final product using IR spectroscopy?

e. Why is only the endo isomer obtained in the experiment? How can it be converted it into the exo isomer?