Experiment 2: Diels-Alder Reaction: Synthesis of cis-Norbornene-5,6-endo-dicaroboxylic anhydride
The main goal of this experiment is to perform a Diels-Alder reaction between 2,3-dimethyl-1,3-butadiene and maleic anhydride, identify the product and hydrolyze to form the dicarboxylic acid. Diels alder reactions are classified as pericyclic reaction, which is a reaction which involves a cyclic rearrangement of bonding electrons, which means that the bonds are broken and reformed instantaneously. The reaction takes place in a single step without the use of intermediates, which is what makes this reaction stereospecific because substituent’s never have a chance to “change around”. When the experiment is complete a colorless platelike crystal will be formed and then they will be compared against the expected values. The melting point range that is found for the resulting crystals will show if a successful product resulted.
Cyclopentadiene is universally used in Diels-Alder reactions and is stable dimer, dicyclopentadiene, which is the Diels-Alder adduct from two molecules of the diene. Because a bottle of cyclopentadiene actually contains the dimmer, it must be converted into the monomer prior to using it as a reactant. Making cyclopentadiene by heating and distillation of the dimer makes it a reverse Diels-Alder reaction. If the initial process of heating and distilling does not yield enough pure cyclopentadiene then a stock solution prepeared by the lab staff can be used to continue the experiment.
Cyclopentadiene Maleic Anhydride cis-Norbornene-5,6-endo-dicaroboxylic anhydride
Diene DienophileDiels-Alder Product
The side reaction which occurs during the production of cis-Norbornene-5,6-endo-dicaroboxylic anhydride is the dimerization of the diene.
The remedy for this side reaction is to distill cyclopentadiene....