Problems Set Week 7

1. Referring to step 3 of the lidocaine project (conversion of (4) to (5))

a. Why do you use a three-fold excess of diethylamine?

b. Why is toluene used and the mixture refluxed for 90 minutes?

c. How do you know if your reaction started?

d. Outline a separation scheme for the isolation of lidocaine. Indicate at each step in which layer your product is.

2. Using Spartan 02, 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 from 0 to 360 degrees in 30 degree increments. Plot the observed energy, the amide bond distance and the natural charge of the nitrogen atom as a function of the dihedral angle. Which conclusion can be drawn from those plots? (Hint: the following article might be helpful in your work: J.Chem.Ed. 2001, 78, 538.)