Ramblings of the QuASI

These are the discussion questions to go with the QuASI REEL lab report due next week. Its some food for thought.  Ill post my idea/thoughts/responses to each of these sometime in the next week.  I need to really do some research first to get all my facts straight.

Discussion Questions ¹

1. The synthesis of these new azo dyes using a procedure adapted from methyl orange was not as easy as it sounds. The solubility of the starting materials we a big issue. What steps would you take to modify the procedure to overcome some of your synthetic difficulties and the uncertainty that resulted?

2. Some of the compounds that were tested were recrystallized and some were not. Why could this be a problem? Why doesn’t Dr. Paul care if what we tested was pure or not? On the other hand, discuss the benefits of working with pure molecules?

3. The “A” in QuASI is for “aqueous”, and some of your products were not soluble enough in water to analyze their properties. Propose changes to the dye molecules structure that might make them more soluble in water without affecting their ability to detect anions.

4. Anions are extremely soluble in water because water strongly hydrogen bonds to these atoms to stabilize their concentrated charges. Would you expect complexing/associating an anion with an organic molecule would be difficult in the presence of so much water? What would you have to do to make your dye molecule a better “life raft” or “seat cushion” for the halides to sit down on?

5. Why would you expect a halide to change the color of an organic molecule in solution?

6. A majority of the UV‐vis analysis studies did not record a significant change in λmax between chloride and bromide containing solutions, yet this may not be a problem with our hypothesis. Consider as many aspects of the experiment that might factor into this negative result. Why did so many people see no change?

References:

(1) Paul, Noel. "Anion Selective Indicator (QuASI) for Aqueous Solutions." Chemistry 255 Research Experience to Enhance Learning. (2011): Print.