Cycloadditions: The Diels-Alder Reactions

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Purpose: • To produce cis-endo-Bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride from cyclopentadiene and Malic Anhydride, using cycloaddition as the mechanism. • To find the purity using the melting point Procedure: Reference: Experiment 10.Cycloadditions: The Diels-Alder Reaction. Hart, H., Crane, L. E., Hart, D. J., and Vinod, T. K., Laboratory Manual for Organic Chemistry: A Short Course, 12th ed., Brooks/Cole, Cengage Learning: Belmont, 2007,pages 133-142. Modifications: - Maleic anhydride weighed in an Erlenmeyer flask - Warm on a hotplate - Wash product with a little ice cold ether - Dry product on large filter paper Observations: Table 1: measured values Compound/Item Measured value Maleic Anhydride 4.4917g Product 4.8398g Product melting point 123.5-141.6 oC Table 2: observed reactions Reaction Observation Warmed Maleic anhydride + ethyl acetate -Maleic anhydride (white powder) dissolved into a clear colourless liquid Adding Ligroin and cooling -Turns to a clear liquid with a white precipitate Adding Cyclopentadiene -Cloudy white liquid during mixing -settled to a bottom layer of white precipitate and a top clear colourless liquid Product White powder During melting point White powder slowly melted to clear colourless liquid Conclusion: In this experiment cis-endo-Bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride was made, and there was a final mass of 4.8398g. Also, the product was light white fluffy crystals. The melting point was 123.5-141.6 oC and melted into a clear colourless liquid. The cyclopentadiene needed for this procedure had to be freshly prepared because even at room temperature it readily undergoes a Diels-Alder reaction with itself to form dicyclopentadiene. The Ligroin was used as a solvent. In the reaction of Maleic anhydride complex with cyclopentadiene, the endo isomer was made

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