Problems Set - Meeting #7

1. Referring to the reaction carried out in the lab, answer the following questions.

a. Benzyne is considered aromatic despite having 8p-electrons. Explain briefly why.

b. How is benzyne obtained in the reaction? Show a balanced chemical equation.

c. The procedure asks to carry out the reaction in a larger container. Why?

d. Why is 1,2-dimethoxyethane used in the reaction and not diethyl ether?

e. Isopropanol is used in the recrystallization step. Would 95% ethanol work as well here? How about ethyl acetate?

2. A UV-Vis spectrum is also obtained for the compound obtained in this week's experiment.

a. Why does the procedure ask to use a quartz cuvette instead of a plastic cuvette (made from methacrylate like last week) this time?

b. Which concentration is needed for the UV-Vis characterization of the TPN? How do you prepare this solution?

c. Which information should you report in your postlab write-up from the UV-Vis spectrum?

d. All peaks due to the target compound are located below 300 nm. Which type of transitions can they be attributed to?

3. Theory of Diels-Alder Reactions

a. The reader mentions that the diene has to be in s-cis conformation. Explain briefly why.

b. Which impact do acceptor and donor substituents have in the reaction?

c. What does the term "secondary orbital interaction" refer to?