The Diels-Alder Reaction Of Anthracene With Maleic Anhydride

The Diels-Alder Reaction of Anthracene with Maleic Anhydride 1 The Diels-Alder Reaction of Anthracene with Maleic Anhydride

Microscale Diels-Alder Reaction

Leah Monroe

March 6, 2003

Organic Chemistry Lab II

Experiment performed on February 25 and 27, 2003

Abstract:

This experiment involved a reaction between anthracene and maleic anhydride via a Diels Alder reaction to yield 9, 10-dihydroanthracene-9,10-α, β-succinic anhydride. Anthracene was the diene and maleic anhydride was the dienophile. The percent yield of the crude product was 69.03%. Following recrystallization of the product using xylene and vacuum filtration, a percent yield of 37.42% for the recrystallized product was collected. This was low due to the fact that some of the crude product was not recrystallized and was instead used to take a melting point of the crude product. It was also low due to several of the crystals being stuck inside the flask and not going into the funnel. The percent recovery from recrystallization was 54.21%. The melting point of the crude product was 261 - 264oC. The melting point of the recrystallized product was 261 - 263oC. Comparing these values with the literature melting point of 262 - 264oC shows that the product was indeed 9, 10-dihydroanthracene-9, 10-α, β-succinic anhydride and that recrystallization yielded a purer product. Upon examination of an infrared spectrum of the product and comparison with anthracene and maleic anhydride spectra, it was found that the product spectrum had similarities with both the anthracene spectrum and the maleic anhydride spectrum. This indicated that the product was an adduct of both anthracene and maleic anhydride, and thus that the experiment was successful.

The Diels-Alder Reaction of Anthracene with Maleic Anhydride 2

Introduction: The purpose of this experiment is to form 9, 10-dihydroanthracene-9,10-α, β-succinic anhydride by way of a Diels Alder reaction between anthracene and maleic anhydride. Anthracene acts as the diene and maleic anhydride functions as the dienophile. Following the reaction, the crude product will be recrystallized. Melting points of both the crude product and recrystallized product will be taken and compared with the literature value. Also, an infrared spectrum of the recrystallized product will be taken. Both melting points and the infrared spectrum will be used to characterize the product.

Materials Used:

150-mL beaker Hirsch funnel, with adapter

boiling chip 2 melting point capillary tubes

Condenser, with tubing Pasteur pipet, with latex bulb

5-mL conical vial microspatula

2 Erlenmeyer flasks, 10-mL 1-mL pipet

25-mL filter flask, with vacuum tubing sand bath

filter paper support stand

glass stirring rod 13 x 100-mm test tube

thermometer, -10 to 260oC

Substances Formula Weight

g/mol Quantity Moles Used Mole Ratio Melting Point

oC Boiling Point

oC

anthracene 178.23 100 mg 5.611 x 10-4 1 to 1 216 - 218 N/A

9,10-dihydroanthracene-

9, 10-α, β-succinic anhydride 276.29 product N/A 1 to 1 262 - 264 N/A

maleic anhydride 98.06 55 mg 5.609 x 10-4 1 to 1 54 - 56 N/A

potassium bromide 119.01 100 mg 8.4 x 20-4 N/A N/A N/A

xylene 106.17 6 mL N/A N/A N/A 137 - 144

Reagents and Properties:

Reaction and its Mechanism:

Overall Reaction: C14H10 + C4H2O3 􀃆C18H12O3

C O C O O + Anthracene (diene) Maleic anhydride (dienophile) C O H H C O O 9,10-dihydroanthracene-9,10-α, β-succinic anhydride

Maleic anhydride (dienophile) C O O C O C O H H C O O Anthracene (diene) 9,10-dihydroanthracene-9,10-α, β-succinic anhydride

The Diels-Alder Reaction of Anthracene with Maleic Anhydride 3

Procedure:

Part 1 - Reacting Anthracene with Maleic Anhydride

Tare a 5-mL conical vial (or 10x 100-mm reaction tube) and record the mass. Weigh 100 mg of anthracene and 55 mg maleic anhydride and place them in the vial or reaction tube. Add 1.0 mL of xylene and a boiling chip. Fit the vial or tube with a condenser, as shown in Figure 3 on page 79 of Chemistry Lab Experiments. Turn on the water to the condenser or add a wet pipe cleaner around the reaction tube. Use a 200oC sand bath to heat the mixture at reflux for 30 minutes, boiling vigorously to ensure good mixing. Cool the mixture to room temperature and prepare an ice bath using a 150-mL beaker. Then cool the mixture in the ice bath for approximately 5 minutes. At the same time, pour 2 mL xylene into a test tube and chill the xylene in the ice bath. Collect the recrystallized solid by vacuum filtration using a Hirsch funnel and rinse the crystals with 1 mL of ice-cold xylene. Weigh the crude product and set aside a small sample to dry. This sample will later be used to measure the melting point of the crude product.

Part 2 - Purifying the Product

To perform recrystallization, place the product in a 10-mL Erlenmeyer flask. Add 1 - 2 mL of xylene and heat the mixture gently in a sand bath until the xylene boils. Gradually add more xylene until all the product dissolves or until no more appears to be dissolving. Be sure not to exceed 3 mL of total volume xylene. If solid impurities are still present, use a Pasteur pipet to transfer the solution to another 10-mL Erlenmeyer flask. Allow the solution to cool to room temperature and then cool the solution in an ice bath for 5 minutes. If it's necessary, scratch the bottom of the flask with a glass rod to induce crystallization. Collect the crystallized solid by