Recall (Section 16-10) that two positions of anthracene sometimes react more like polyenes than like aromatic compounds.
(a) Draw a Kekulé structure that shows how the reactive positions of anthracene are the ends of a diene, appropriate for a Diels–Alder reaction.
(b) The Diels–Alder reaction of anthracene with maleic anhydride is a common organic lab experiment. Predict the product of this Diels–Alder reaction.
The resonance energy of anthracene is 84k. cal/mol which is less than the resonance energy for three separate benzene rings so anthracene is not as strongly stabilized as benzene.
Anthracene undergo, 1,4 - addition at the 9-and 10-positions to give a product with two isolated, fully aromatic benzene rings. So anthracene behave like a diene and can undergo Diels-Alder reaction.
Thus, anthracene has diene character and undergo diels alder reaction.
(b) Anthracene undergo Diels-Alder reaction with maleic anhydride.