Diels Alder Reaction Lab

The purpose of this lab was to carry out two Diels-Alder reactions; Part 1 focused on obtaining, and characterizing through IR spectroscopy and melting point range, a diastereomeric mixture of 7-oxobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride produced from furan and maleic anhydride, while the goal in Part 2 was to produce dihydroanthracene succinic anhydride from anthracene and maleic anhydride and characterize the product using its melting point range.
Since more extensive experiments such as mass spectroscopy, 1H NMR, and/or 13C NMR were not carried out in either part, the product structures’ cannot be confidently ascertained. Nonetheless, it will be assumed that at least the predicted products were isolated. For Part 1, the product in the reaction mixture was a near-transparent solid mass of prismatic crystals, while the isolated crystals were long, needle-like, and translucent white. This observation agrees with the literature appearance of “crystalline and white.” The melting point range obtained was 109.6℃-114.2℃, while the literature values were 80℃ for the endo product and 114℃ for the exo product. For Part 2, the final reaction mixture was a deep yellow

Indeed, the wide range of the measurement may be due to impurities, but is probably more due to a small amount of endo product, which has a much lower melting point literature value. The dominance of the exo (thermodynamic) product is unusual for a Diels-Alder reaction, where the endo (kinetic) product usually dominates. Part 1’s results could be due to the reaction conditions favoring the thermodynamic product. The reaction ran for an entire week, allowing enough time for the Diels-Alder reaction to equilibrate (since it is technically a reversible reaction) and favor the more stable (exo)