Cyclopentadiene Recovery

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Maleic anhydride underwent the Dials-Alder reaction with distilled cyclopentadiene as the dienophile. The reaction was a cycloaddition which produced cis-Norbornene-5,6-endo-dicarboxylic Anhydride surface. (1) Product one had a mass of 9.351 grams and product two had a mass of 9.572 grams. The theoretical yield was found to be 10.047 grams, which makes the percent yield to be 93.07%. Melting Points were found to confirm the purity of the product. Product one had a melting point of 163.7-164.8°C. Product two had a melting point of 162.2-163.9°C.
IR Spectroscopy (nujol) are carbonyl peaks (1773.4 cm-1), Sp3 C-H peaks (2921.5 cm-1), Sp2 C-H (3000 cm-1). The carbonyl peaks prove the presence of an acid anhydride. H’NMR (CDCL3)
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Methylene chloride is added to the flask with the diester. The seperatory funnel is attached to the flask with 1.0 M bromine inside. Bromine is added to ester mixture drop by drop until the solution stays a yellow color. After ten minutes a cyclohexene and methylene chloride mixture is added drop by drop to remove the excess bromine. Ester solution is placed on the rotary evaporator at 45°C. Ethanol was added to the product. Solution was cooled in an ice bath for thirty minutes and crystals began to form. Solution was vacuum filtered with a Hirsch funnel. The mass of the product was 0.47 g. MP 70.1-75.3°C The theoretical yield was .74 g. This makes the percent yield 64%. The expected melting point was 123-125°C. The diacid was not the product formed. With IR, HNMR, and CNMR data the identity of the final product was found. IR (neat) 2989.8 and 2955.7 (Sp3 C-H), 1785.8 (Lactone ester), 1735.8 (ester). 1H NMR (CDCL3) 5.073 ppm (d, 1H), 4.991 ppm (d, 1H), 4.637 ppm (d, 1H), 4.599 ppm (d, 1H), 3.764 ppm (s, 3H), 3.364 ppm ( m, 1H), 3.130 ppm (m,1H), 2.948 ppm (d, 1H), 2.558 ppm (m, 2H), 2.363 ppm ( m, 1H), 1.934 ppm (s, 1H), 1.728 ppm (s, 1H). 13C NMR (CDCL3) 177.037 ppm, 171.388 ppm, 88.171 ppm, 53.125 ppm, 50.270 ppm, 49.297 ppm, 49.328 ppm, 49.040 ppm, 41.317 ppm, 36.441
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