Problems Set #4
ATTN: answers to the below questions are due at the start of your lab period; these answers should be part of your pre-lab write-up.
The Lidocaine NMR spectra can be found here.
1. What is the advantage of using Ce(OH)3(OOH) for the oxidation of the alcohol over conventional reagents for the oxidation?
2. Why is it important to cool down a solution slowly during recrystallization?
3. Suggest a method to recover CeCl3 from the Ce(OH)3 formed in the oxidation of the alcohol.
4. How can you prove by spectroscopy that the oxidation was successful?
5. Using Spartan Pro, do the following calculations for DEET (N,N-diethyl-m-toluamide). Define a dihedral angle between the carbonyl group and the adjacent amine function (OCNC). Perform the calculations using AM1 level (constraints checked) for the following dihedral angles: 0, 30, 60, 90, 120, 150 and 180 degrees. Record the energy, the bond distance between the carbonyl carbon and nitrogen of the amide group and the NPI charge on the nitrogen atom.
a. Using Excel plot the resulting energy (kJ/mol) as a function of the dihedral angle.
b. Calculate the HOMO and LUMO orbital for the configuration with the highest and the one with the lowest energy. How are the structures of the molecule different in those two extreme forms?
c. What happens to the bond distance and the charge on nitrogen atom if the dihedral angle changes? Rationalize the trends.