A key characteristic of these reactions is their stereospecificity. Conclusion Through the Diels-Alder reaction, 27.6% yield of cis-Norbornene-5,6-endo-dicarboxylic anhydride was produced. Nonetheless, the yield of product is still low due to the following: losses due to the mechanism of transfer and cyclopentadiene forming dicyclopentadiene. The Diels-Alder reaction is categorized as a pericyclic reaction, which involves the overlap of spatial orbitals as well as the hybridization and delocalization of the molecules.1  As a unique characteristic, this reaction is characterized as a concerted cycloaddition reaction indicating a lack of intermediate in the mechanism. In a 25 mL Erlenmeyer flask, maleic anhydride (1.02 g, 10.4 mmol) and ethyl acetate (4.0 mL) were combined, swirled, and slightly heated until completely dissolved. A 4+2 cycloaddition occurs between the electron-rich diene, cyclopentadiene, and the electron-poor dienophile, maleic anhydride. The change from Sample A to Sample B thus increased the yield by reducing solubility of crystalline product. The product had the following properties: 0.47 g (27.6% yield) mp: 163-164 °C (lit: 164 °C). A total of 0.47 g of the product was collected; a yield of 27.6%. Cyclopentadiene is composed of a five-carbon ring where two of the carbon-carbon bonds of the ring are double bonds; the double bonds are separated by a single σ bond, making the double bonds conjugated. An Experimental and Theoretical Study of Stereoselectivity of Furan−Maleic Anhydride and Furan−Maleimide Diels−Alder Reactions. The undissolved solids were removed form the hot solution by filtration and once they cooled, white crystals began to form. maleic anhydride should produce 2.27g of 4-cyclohexene-cis-dicarboxylic anhydride and 2.54g of 4-cyclohexene-cis-1,2-dicarboxylic acid (Eqs.1 and 2). Strategies, such as using hormones have been explored with haste because of the potential damage many pests have on agricultural produce.2  These compounds have been researched and related back to their concerted cycloaddition mechanism. The distinction of the presence of the endo isomer was proven by analyzing physical properties of both possible isomers. In this laboratory we will perform a cycloaddition reaction between a conjugated diene (cyclopentadiene) and a dienophile (maleic anhydride) to yield an interesting Diels-Alder adduct. Regarding the specific reaction between cyclopentadiene and maleic anhydride, the endo isomer, the kinetic product, was formed because the experiment was directed under mild conditions. CHEM 2312 Lecture Notes - Maleic Anhydride, Cyclopentadiene, Endo-Exo Isomerism Changing the nonpolar solvent petroleum ether to hexane caused the largest effect on yield based off the Wiki data. We start with the balanced equation. The 1H NMR spectrum of the product revealed a peak in the alkene range at 6.30 ppm, H-2 and H-3 (Figure 1). Cyclopentadiene (140 mg) or maleic anhydride (175 mg). 13C NMR (CDCl3, 75Hz) δ: 171.3, 135.5, 52.7, 47.1, 46.1 ppm. The Journal of Organic Chemistry 2005, 70 (16) , 6295-6302. Increasing the amount of petroleum ether reduces the solubility of the final product in solution; reducing the final product’s solubility causes an equilibrium shift to crystallize more of the final product. A diels-Alder reaction of cyclopentadiene with Maleic Anhydride experiment was conducted in lab. bicyclic anhydride (cis-Norbonene-5,6-endo-dicarboxylic anhydride).The percent yield of the product was calculated and found to be 39.01%. Petroleum ether is composed of a mixture of larger alkanes (more than six carbons), whereas hexane is only composed of six-carbon alkanes. Take the reaction mixture back to your bench and swirl the solution in an ice bath until the product has finished precipitating. Melting point determination found the melting point range of the products to be … 2 Pavia, L; Lampman, G; Kriz, G; Engel, R. A Small Scale Approach to Organic Laboratory   Techniques, 2011, 400-409. This reaction can form new carbon-carbon bonds and new stereocenters. DOI: 10.1021/jo050759z. In 1928, Otto Diels and his student Kurt Alder at the University of Kiel in Germany first reportedtheir work in the reactions of electron poor alkenes with electron rich dienes to form substitutedcyclohexenes. cyclopentadiene + maleic anhydride→DA adduct. Finally, cyclopentadiene (1 mL, 11.9 mmol) was added to the mixture and mixed extensively. 3 Myers, K.; Rosark, J. Diels-Alder Synthesis, 2004, 259-265. By analysis of NMR spectroscopy and physical properties of the specific isomers, the difference between the possible products can be identified. Cis-Norbornene-5,6-endo-dicarboxylic anhydride Cyclopentadiene was previously prepared through the cracking of dicyclopentadiene and kept under cold conditions. A reaction was performed in which 0.25 mL of 1,3-cyclopentadiene was reacted with a slight excess of maleic anhydride to make 0.36 g of … General: All reagents were provided by Sigma-Aldrich from Texas A&M University Chemistry Department. Anthracene acts as the diene and maleic anhydride functions as the dienophile. [X. Diels-Alder Reaction, Cyclopentadiene and Maleic Anhydride A. A peak at 1089 cm-1 represented the carbon-oxygen functional group. Weigh the product and record the mass as theoretical yield. which was calculated by dividing the theoretical yield of 84 grams and multiplying it by 100%. Explanation: We must first identify the limiting reactant, and then we calculate the theoretical yield. Impurities of ethyl acetate appeared at 46.6, 25.8, and 21.0 ppm accompanied with acetone at 30.9 ppm. 165°, which has the endo configuration, has been found to rearrange to the exo isomer, m.p. Sample A was purified by vacuum filtration but otherwise prepared under the same procedure as the sample from Week 1. Reaction B. Based on the interaction between a conjugated diene and a dienophile, different stereoisomeric compounds are formed. Reaction Mechanism The scheme below depicts the concerted mechanism of the Diels-Alder reaction of cyclopentadiene and maleic anhydride to form cis-Norbornene-5,6-endo-dicarboxylic anhydride. Reaction of Cyclopentadiene with Maleic anhydride To begin the reaction I added 1.003g of Maleic anhydride to a 25ml Erlenmeyer flask. Viewed 14k times 1 $\begingroup$ A Diels-Alder reaction happens between 9-Anthracenemethanol (208.26 g/mol) and N-Methylmaleimide (111.10 g/mol). A sample of the Week 1 product was tested by melting point analysis and found to have a melting point range of 152°C-155°C. Results and Discussion When combining the reagents, a cloudy mixture was produced and problems arose in the attempt to completely dissolve the mixture.