The Diels-Alder reaction between furan and maleic anhydride took a couple of days to goto completion while the adduct between á-terpinene and maleic anhydride formed withinminutes. What factor may have contributed to the low reactivity between furan andmaleic anhydride?

Answer and Explanation:

In the Diels Alder reaction there is an overlap between the HOMO and the LUMO which is thermally allowed to happen. The endo components are usually more favored due to the orbital interaction. The so called transition state for exo component is much higher in the energy than transition state in endo component. Therefore the endo product tends to have low activation energy and thus it tends to form faster.