Brad Mueggenborg
CHEM 2315-006
Experiment 8: The Diels-Alder Reaction
The purpose of this experiment was to make a Diels-Alder product using the chemicals: furan, maleic anhydride and toluene. Once this was achieved the weight of the product, the percent yield, and the melting point were to be taken and the remaining sample was to be given to the TA. The reaction that took place during this experiment was the following:
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Furan Maleic Anhydride DA Product
As you can see the furan mixes with the maleic anhydride to yield a crystalline DA product. The weight of the product was 0.869 grams giving 5.23 x 10-3 moles. The percent yield was given by the moles of the product divided by the moles of the limiting reagent, which happen to be Maleic anhydride giving 1.0198 x 10-2 moles, which was 51.28%. The melting point of the product was 114 oC.
The mechanism that takes place in this reaction is very simple. The Toluene is added to the solid maleic anhydride and heated until the solid dissolves. Once dissolved the Furan is added and refluxed for half an hour while a white precipitate forms meaning the reaction is taking place. Once done, the mixture is cooled and suction filtered while washing with toluene. The toluene’s purpose in this experiment is to take out any impurities and to dissolve the maleic anhydride, if water was added to the mixture the anhydride would suck up the water and continue to stay solid. In order to get a high yield from the reaction you would reflux the mixture for longer and probably use less toluene. The temperature during the reflux had to stay below 32 oC because the boiling point of the furan was 32 oC and you did not want to evaporate one of the main reactants. The purity of the product was only about 50 percent, the other 50 percent was most likely some toluene that reacted with the product. The only error that seems to be apparent in this experiment is the slight difference in boiling point of the book’s product and the experiment’s product. The book says it should be about 108 oC where as the experiment product came to 114 oC. This is most likely due to heating the product in the boiling point tester faster than it should have been heated.
During the experiment the condenser was cooled in order to keep the furan cooler than the sand and avoid it from boiling out during the reflux. The reflux was run for half an hour so that the chemicals could react with one another at a higher temperature. An important part of any experiment is safety and in this experiment it was especially important. The gloves were worn because the furan is a lachrymator meaning it is extremely hazardous to your health.
When the experiment was completed and the melting point was taken along with the computations the remaining product was given to the T.A.
References:
- Epstein W. W., J. L. Sidel, C. S. Young, Organic Chemistry, Experiments and Techniques, Hayden McNeil, 2008, 45-48.
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