Diels-Alder Rxn

Experiment #4

7-23-07 T.A. Michael Hall

Diels-Alder Reaction

Introduction:

The purpose of the experiment is to use the Diels-Alder reaction to produce cyclohexene-cis-1,2-dicarboxylic anhydride by combining 1,3-butadiene and maleic anhydride. The initial product will hydrolyze to produce cyclohexene-cis-1,2-dicarboxylic acid. Both of the products will be tested with bromine and potassium permanganate to determine if unsaturation has occurred.

The Diels-Alder reaction is used in chemistry to combine diene molecule with a dienophile to produce a cyclohexene ring and a bicyclic compound. In these reactions there are three double bonds in the reactants which are converted into two new single bonds and one new double bond. This reaction is very helpful because it does not require lot energy to perform this experiment and produce the products.

Procedure:

1) Set up the apparatus the same as in the chlorination experiment #3

2) Confirm the weight of the samples before beginning the experiment

3) Combine in a mixture:

a. 2.5 g of 3-sulfolene

b. 1.5 g of maleic anhydride

c. 1 mL of xylene

4) Start warming the reactants maleic anhydride and 3-sulfolene in a 25-mL flask so they dissolve into the xylene

5) Before coming to reflux be careful to avoid vigorously heating so the butadiene is not lost before it has a chance to react.

6) Heat the reaction to reflux for 30 minutes after all the solid starting materials have dissolved.

7) Add 10 mL of xylene to dilute the mixture.

8) After the mixture is heated and stirred, transfer it to an Erlenmeyer flask

9) Add 5 mL of petroleum ether for good recovery

10) Cool the flask in an ice-bath

11) Collect the crystals with a Buchner funnel.

12) Obtain the melting point of the pure DRY anhydride

13) To perform the unsaturation bromine test:...