Researcher

Marshall Moritz

Objective

To determine the solubility of pyrene in acetonitrile by NMR spectropscopy.

Procedure

Saturated solutions of pyrene in acetonitrile were prepared by adding excess solute to 250uL of solvent in a half-dram vial. The vials were vortexed for approximately 10 seconds and if necessary, more solute was added until after vortexing, precipitate remained on the bottom of the vial. The vials were sonicated until solid remained for 30 minutes of consecutive sonication. The supernatant was then removed from the vials by Pasteur pipette. NMR tubes were labelled appropriately with A for acetonitrile, and numbered 1, 2, and 3 for each trial. 2-3 drops of the supernatant were added to 500uL of CDCl3 in the appropriate NMR tubes. An NMR of each sample was taken on the 300MHz Varian instrument.

Results


Spreadsheet Exp108

Spectra

ONSCExp108A1 Raw data for JCAMP dx file ONSCExp108A1
ONSCExp108A2 Raw data for JCAMP dx file ONSCExp108A2
ONSCExp108A3 Raw data for JCAMP dx file ONSCExp108A3

Discussion

The concentration of pyrene in acetonitrile had not been previously reported at the time of this experiment. Thus the values generated in this experiment could not be compared to any other values but themselves. There were no statistical anomalies in the solubility of pyrene in acetonitrile [1]; the set of values for each solvent was very uniform, thus suggesting the data is reliable. The NMR spectra for all samples did not show distinct peaks for each hydrogen of the pyrene molecule, thus the spectra was integrated for all 10 hydrogens over the range pf peaks. Also, the NMR speactra for sample A3 showed an extra peak at 4.75ppm, thus there may have been an impurity, however this did not affect the results. The experiment generated good results, and though this does not account for potential uniform experimental errors, the experiment was successful.

Conclusion

The solubility of pyrene in acetonitrile was found to be 0.09M, 0.08M, and 0.07M. The mean value was 0.08M and the standard deviation was 0.01.

Log

2009-06-10
10:45--Added 250uL of acetonitrile to 3 vials labeled A1, A2, and A3.
10:48--After adding 2 small scoops of pyrene to vials A1, A2, and A3, the vials were capped and vortexed for approximately 10 seconds. This was repeated one time and the solution was found to be saturated.
10:51--All vials A1, A2, and A3were set in a small beaker filled one-third with water and placed in the sonicator. The temperature was read at 20.5C and the timer was set to 30 minutes.
11:22--All vials were removed from the sonicator and set out to cool to room temperature in a water bath.
12:10--All vials were seeded with a crystal of pyrene to induce any further crystallization and ensure the supernatant was not supersaturated.
12:14--The supernatants were removed from each vial by Pasteur pipette, as the supernatant was easily separated from the remaining solid in each vial.
12:18--NMR tubes were prepared for each vial by taking the respective supernatants and adding 500uL of CDCl3 to appropriately labeled NMR tubes.
12:30--The NMR spectra of all vials were taken on the 300MHz Varian instrument.

References

[1] Solubility of pyrene in non-aqueous solvents

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