The reaction was with 5mmol of Anthracene and 5mmol of Maleic Anhydride to generate the Diels-Alder product. Why was xylene the solvent of choice?
There are three reasons why xylene was the solvent of choice:
1. Xylene has a high boiling point (~140 °C).
Since the solution of reactants is so concentrated, the boiling point of the refluxing mixture may be closer to 180 °C. The higher the temperature, the faster the rate!
2. The product is less soluble in xylene than the reactants are, so the adduct crystallizes from the solution on cooling.
3. The xylene (m.p. ~-50 °C) will not solidify when the reaction mixture is cooled in ice water.
Thus, you can easily filter off the solid adduct for later purification.