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Sunday, March 3, 2013

The Diels-Alder Reaction of Anthracene with Maleic Anhydride - Lu Le Laboratory

The Diels-Alder reaction is a cycloaddition reaction, a reaction in which two molecules undergo addition to yield a cyclic product. Various types of cycloaddition reaction are known. Because a Diels-Alder reaction involves two double bonds(four π electrons) of a conjugated diene and one double bond (two π electrons) of the other reactant, this type of reaction is called [4+2] cycloaddition. In a Diels-Alder reaction, the conjugated diene is referred to as the diene; the other compound is called the dienopile.

[4+2] cycloaddition

        This Diels-Alder reaction is carried out by boiling the reactants in xylene. Both reactants are soluble in xylene, and the reaction is rapid because of the high boilig point of the solvent, xylene. As the mixture cools, the product crystallizes. The product is isolated by filtration; if the starting anthracene was pure, it requires no further purification.

         It is difficult to remove the high-boiling xylene by “air-drying” the crystals. In addition, exposure to the air results in the hydrolysis of anhydrides by atmospheric moisture.

        For this reason, the product is dried under an inverted beaker along with some paraffin wax, which dissolves xylene vapors and thus acts as a “dessicant.”

Reaction Equation


1.      Anthracene: 1.0g

2.      Maleic anhydride: 0.5g

3.      Xylene: 17.5mL

1.      Place 1.0g anthracene in a 25mL round-bottomed bottle
2.      Pour 17.5mL xylene into the bottle
3.      Add 0.5g maleic anhydride in the solution

4.      Reflux the mixture for 30 minutes.

5.      After the round-bottomed bottle cools to room temperature, put the bottle in an ice bath.

It is still very hot now

6.      Filter the solid by vacuum and wash the product with ice-cold petroleum ether.

7.      Collect the solid in a sample bottle and put some wax films with the solid.

Experimental Record

Weight of anthracene
Weight of 9,10-dihydroanthracene-9,10-endo-α,β-succinic anhydride

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