Question

1. Three (03) students are planning to run Diels-Alder reactions using maleic anhydride as dienophile and three (03) different dienes (A, B, and C). Student A will be using cyclopenta-1,3-diene (compound A), Student B will be using buta-1,3-diene (compound B) and student C will be using 1,2,3,7,8,8a-hexahydronaphthalene (compound C).

1. Draw the reaction schemes for Student A, Student B and Student C using the above given starting materials (write “NO REACTION” whenever the reaction is impossible).

Student A’s reaction scheme (2 pts)

Student B’s reaction scheme (2 pts)

Student C’s reaction scheme (2 pts)

2. Which of the three reactions would you expect to be the fastest? Why?(2 pts)

3. Student A would have to crack the cycolpentadiene before it can be used, while student B will use the butadiene as purchased; explain why? (4 pts)

(d). Why is maleic anhydride a much better dienophile than ethylene (CH₂=CH₂)? (2 pts)

(e). When producing Diels-Alder adducts using maleic anhydride as the dienophile, why is it important that reagents and apparatus be dry? (2 pts)

(f). Why is Diels-Alder reaction exothermic process? Explain considering bond cleavage and bond formation contribution to the enthalpy change (2 pts)

Answer 1