Question

EXPERIMENT 2A DIELS-ALDER REACTION OF ANTHRACENE REFERENCES Pavia et al (4/e): Tech. 6.1/6.2, 7.2-7.4 Klein (1/e) pp. 784-792 EQUATION heat Diels-Alder Adduct 9,30-dihydroanthracene-9,10- endo-o B-seccinic anhydride mp 262264 PROCEDURE Place 0.200 grams of anthracene and an equal molar amount of maleic anhydride in 5 mL of xylenes in a 10-mL round-bottom flask with a magnetic stir bar. Attach a water-cooled condenser and reflux for 60 minutes. Allow the solution to cool to room temperature and then place the flask in an ice bath. Filter the ppt., dry it, and take the melting point of the product. Calculate the % yield. Obtain both the IR and UV spectra of the product. We will use 2-propanol for the UV solvent. You will need to heat the solution to get the Diels-Alder adduct to completely dissolve, so initially make the solution in a small beaker using approximately 5 mL of 2-propanol. After heating, allow the solution to cool to room temperature and transfer the solution to a 10 ml. volumetric flask. Carefully fill the volumetric flask with solvent to the 10-mL mark. The IR and UV spectra of the starting materials are provided at the end of this lab. These spectra should be removed and attached to your notebook. You will refer to them as you discuss any similarities or differences between them and the spectra of your Diels-Alder product. 19

Answer 1

The reaction is Carried out in xylene as non polar enough to dissolve both reactants efficiently, Moreover, the boiling point if xylene in high enough to provide sufficient rate of reaction. rightarrow Workup is also easy here. The product is Colours as the extended resonance is restricted. Initially arhracne have three benzene ring in Conjugation but after the formation if product, the middle ring is no longer in Conjugation. Endo product is formed due to the fact that the reaction is kinetically controlled. Moreover the transition state that formed is stable when HOMO& LUMO orbital's overlapped to undergo a Connected mechanism, where the orbital of diemphile and diene interact to provide extra stabilization. Cis - 2 methyl - 2, 4, - hexadiene is more reactive as for diels - Alder reaction reacts a cis diene is required where bond making and bond breaking can occur simultaneously. Moreover, the