Final Project: Spring 2011- Part II

The first synthesis project began with the Diels Alder reaction we performed in Fall. The reaction of xylenes with maleic anhydride in refluxing xylenes yields cis-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid anhydride (better known as the “Diels Alder adduct”). This was boiled with aqueous base the following week to yield the dicarboxylic acid. The dicarboxylic acid can be easily precipitated from the aqueous solution with hydrochloric acid. Interestingly, a sample NMR shows that both cis and trans isomers are present in this product which starts out as a gooey substance before hardening into an amorphous solid. The dicarboxylic acid was then esterified in boiling ethanol and sulfuric acid. The ester is extracted away from the aqueous solution with methyl t-butyl ether. Preliminary NMR data seems to indicate only the trans isomer is present. The melting points of the three products went from ~260, to >260, to ~65 degrees C. It would be interesting to compare this product to one obtained directly from anthracene and trans diethylmaleate.


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