Synthesis Of Dimethyl Tetraphenylphthalate And Dimethyl Acetylene
1208 Words5 Pages
tetraphenylcyclopentadienone- or TPCPD- as our diene, and our dieneophiles were three different alkenes with three different substituent groups (Kilway, “Formation”). The first reaction, synthesis of dimethyl tetraphenylphthalate, combined TPCPD and dimethyl acetylene-dicarboxylate using nitrobenzene as a solvent. Nitrobenzene makes a perfect solvent for this reaction because it’s boiling point is so high (210-211⁰C) (Kilway, “Formation”). This allows the reaction to reach the proper temperature to fulfill the activation energy needed to combine these two stable products without destroying the solvent (Drew-Gounev). If the solvent was destroyed, it may prevent the intended products from being produced. In this reaction, a strained…show more content…
Like in the mechanism for the first reaction, diphenyl acetylene also added to the carbons alpha to the carbonyl group. This route provides decreased steric hindrance and facilitates the 1,3-diene addition of a Diels-Alder reaction. Again, an unstable bridgehead intermediate is formed, but the release of carbon monoxide from the molecule drives the reaction forward to form an aromatic product. This molecule would not be planar for the same reason as dimethyl tetraphenylphthalate. The phenyl groups are joined to the central benzene by a single sigma bond, which allows free rotation. The free rotation would ease steric overlap between the substituent groups. This product would be considered less stable in comparison to tetraphenylphthalate due to its bulky substituent groups causing steric interference. The mechanism for formation of this product is seen in Figure 5.
Mechanism of the synthesis of hexaphenylbenzene. Figure 5. In the third reaction, formation of tetraphenylnapthalene, benzyne was reacted with our diene as the dienophile. There are reactive intermediates in both the formation of benzyne and the Diels-Alder reaction of benzyne with TPCPD (Kilway, “Formation”). Benzyne, being a very unstable product, was prepared in situ to facilitate immediate interaction with TPCPD. As seen below in Figure 6, the reaction used anthranilic acid and isoamyl nitrite in glyme to form our benzyne dieneophile. This reaction causes the release