last updated Friday, November 7, 2003

Meeting 14 (Nitration)

1. Referring to the nitration experiment, answer the following questions:

a. How do you generate the nitronium ion in the laboratory?

b. What is the function of the sulfuric acid in the experiment?

2. During the nitration step, explain why does the amount of the dinitro derivative increases with increase in temperature of the reaction mixture? How can you prevent this from happening? Explain.

3. Using Spartan 2002, perform an AM1 calculation for for the NO₂⁺, NO₂, CH₃CO⁺ and acetone. Include the simulation of the Density map for the HOMO and LUMO of each molecule/ion. Note that NO₂⁺ and CH₃CO⁺ are cations, while NO₂ is a radical (doublet). By looking at the individual density of teh HOMO orbital, can you explain the following trends?

a. The nitronium ion is a much stronger electrophile than trhe acylium ion?

b. The nitrogen in NO2 has more of a nucleophilic character than an electrophilic one.

c. The bond distances are shorter in the cations than in the neutral species. Why?