Problems Set - Meeting #4
Announcements:
1. Make sure that you make progress on your formal report as well in terms of literature search and writing the parts that you completed already in the lab.
2. The second quiz will be administered on Wednesday, January 21, 2009 at 8:00 am covering the resolution and the ligand synthesis and techniques involed in these projects. Bring a ruler, non-graphing calculator and pen with you. Please make sure that you arrive on time (this means that you are seated by 7:55 am!!!). Late arrivals will not be allowed into the class room since they disturb the rest of the class!! This also means that you will not be allowed to take the quiz!!!
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.
1. Arginine, an amino acid that serves as precursor to NO, and also helps to decrease blood pressure is found in may dairy products. A student synthesized the compound in the lab and wants to evaluate its purity.
a. He obtains the optical rotation for a solution of 0.35 g in 5 mL of water. The student observes an optical rotation of a= +0.60o in a 10 cm cell. Determine the optical purity of the sample.
b. What would change if the solution was prepared in 6M HCl or 0.5 M NaOH solution?
2. Referring to the synthesis and characterization of the Jacobsen ligand, answer the following questions.
a. The initial stage of the reaction the tartrate salt is reacted with potassium carbonate in water. Provide a balanced equation and rationalize the choice of solvent. Why is potassium carbonate used here and not potassium hydroxide?
b.After the initial part of the reaction (see a.), 95% ethanol is added. Explain why.
c.What should the student observe if the reaction ran according to plan?
d.Why is water added to the reaction mixture prior allowing it to cool to room temperature?
e. The ligand exhibits a fairly strong intramolecular hydrogen bond. Give three pieces of evidence for this observation.
f. Which solvent is used to acquire the UV-Vis spectrum of the ligand? Which type of cuvette should be used here? What's the proper concentration?