Document 46 - Diels-Alder Reaction lab report PDF

Preview

Summary

Diels-Alder Reaction lab report...

Description

Diels-Alder Reaction HIBA RADAD CHEM-2123-003

Abstract: The purpose of this experiment is to introduce the important cycloaddition reaction. In this experiment, 0.527 g of Maleic anhydride, 1 mL, 85 % pure of phellandrene, and 3 mL of Anhydrous acetone is used to form this reaction. The % yield is collected at 27.8%, and the observed melting point is collected at 123-125 °C.

Introduction: The Diels-Alder reaction is an industrially important well-characteristic cycloaddition. Since the primary report by Rideout and Breslow on the greater acceleration and improved internal selectivity of Diels-Alder interactions in water, these effects have been partly attributed to the benefit of reducing the hydrophobic surface area. In addition to the potential catalytic value, the use of water as a potential "green" solvent for organic synthesis is appealing. The Diels-Alder reaction is an example of a [4+ 2] cycloaddition reaction in which an alkene adds in a 1,4 addition to a diene. In this experiment, alpha-phellandrene will react with maleic anhydride. The alpha-phellandrene is a natural product derived from cedar wood and has a characteristic cedar wood odor. It is not 100% pure so the directions call for an added amount to be used to compensate for the impurity. Maleic anhydride is a white solid. It can hydrolyze with water to give maleic acid so water should be avoided if possible. With prolonged exposure to moisture, the anhydride group in the product may convert to the diacid which will have different properties. The final bicyclic product is usually obtained without difficulty.

Diels-Alder is a 6π electron circular reaction. The diene provides 4π electrons and dienophile 2π electrons to form bonds. The Diels-Alder reaction belongs to [4 + 2] cycloadditions according to Woodward-Hoffmann nomenclature. The purely formal method for identifying the participating electrons consists of calculating the electron flow arrows which are used to illustrate the mechanism and multiplying it by two. Each arrow moves two electrons. There are 3 arrows representing the reaction, so 3 * 2 = 6 electrons. The number of electrons involved in the cycloaddition determines whether the reaction follows the supra-supra mechanism (s + s) or the supra-antara mechanism (s + a).

Materials and Methods: Maleic anhydride, phellandrene, Anhydrous acetone, 25 mL round bottomed flask, water-cooled condenser, 20 mL beaker, Hirsch funnel.

Experimental Procedure:

1.

Maleic anhydride (0.527 g, 5.4 m moles) and  -phellandrene (1 mL, 85 % pure, 5.4 m

moles) was placed into a 25 mL round bottomed flask and attach a water-cooled condenser. 2.

Anhydrous acetone (3 mL) was added through the top of the condenser and the reaction

mixture was swirled. 3.

The reaction was exothermic, and a yellow color appeared at that point.

4.

The reaction was heated under reflux for 1 hour using a steam bath or hot water bath.

5.

After this time, the condenser was carefully removed, the reaction mixture was poured

into a 20 mL beaker and the acetone solvent was allowed to evaporate to approximately half of its original volume. 6.

The reaction was allowed to cool to room temperature, then the reaction vessel was

cooled in an ice bath to induce crystallization of the Diels-Alder adduct (scratching with a glass rod may be required). 7.

The product was filtered off using a Hirsch funnel, the flask got washed with a small

amount of ice-cold acetone. 8.

The final product got dried and weighed, the melting point was recorded, and the percent

yield was determined. 9.

The product got recrystallized when it required, (i.e. if the melting point of the product is

much lower than expected) using the minimum amount of warm methanol (be very careful to not overheat as methanolysis of the anhydride group could occur).

Results and calculations:

Mass of maleic anhydride: _____0.527_____ g Moles of maleic anhydride: _____5.4_____ m moles Amount of phellandrene: ______1 mL, 85 % Pure____ Moles of phellandrene: _____5.4_____ m moles Theoretical yield: _____1.265_____ g 5.4 m mole x (1 mol/1000 m mol) x 234.29 g/mol Theoretical mole: _____5.4_____ m moles Actual yield: _____0.352_____ g Moles of the product: _____1.50_____ m mol % Yield: _____27.8_____% (0.352/1.265) x 100% Expected melting point: _____126-127_____°C Observed melting point: _____123-125 _____°C

Discussions: In this experiment, 0.527 g of Maleic anhydride, 1 mL, 85 % pure of phellandrene, and 3 mL of Anhydrous acetone was used to form this reaction. The mass of maleic anhydride was collected at 0.527 g, and the moles of maleic anhydride was collected at 5.4 m mol. The amount of phellandrene was collected at 1 mL, 85 % Pure, and the moles of phellandrene was collected at 5.4 m mol. After the calculation the theoretical yield was collected at 1.265 g, and the theoretical mole was collected at 5.4 m mol. The actual yield was collected at

0.352 g, and the moles of the product was collected at 1.50 m mol. After calculating the % yield which is (0.352/1.265) x 100% it was collected at 27.8%. The expected melting point was collected at 126-127°C, and the observed melting point was collected at 123-125 °C.

Conclusion: Based on the observed and calculated data, the % yield was collected at 27.8%, and the observed melting point was collected at 123-125 °C. The purpose of this experiment was introducing the important cycloaddition reaction. 0.527 g of Maleic anhydride, 1 mL, 85 % pure of phellandrene, and 3 mL of Anhydrous acetone was used to form this reaction.

References: file:///Users/hibaradad/Downloads/Expriment%202-1.pdf file:///Users/hibaradad/Downloads/QM-MM%20Modeling%20Finds%20DielsAlder%20Reactions%20are%20---1%20(1).pdf

Material Safety Data Sheet Understanding hazards associated with chemicals is an integral component of safe and responsible laboratory practice. Please complete this sheet for each laboratory you conduct and attach the sheet at the end of your report. Attach multiple sheets if using more than six chemicals. MSDS Information

maleic anhydride

Solid

0.527 g

Health:3 Flammability:1 Physical Hazard:1

phellandrene

Liquid

1 mL

Anhydrous acetone

Liquid

3 mL

Personal Protection:0 Health:3 Flammability:3 Physical Hazard:3 Personal Protection:2 Health:2 Flammability:0 Physical Hazard:2 Personal Protection:0...