Researcher

Marshall Moritz

Objective

To determine the solubility of p-toluenesulfonic acid in 2 different solvents, acetonitrile and toluene, by NMR spectropscopy.
[Add any missing H NMR spectra in ChemSpider JCB]

Procedure

Saturated solutions of p-toluenesulfonic acid in acetonitrile and toluene were prepared by adding excess solute to 200uL 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 filtration by Pasteur pipette. NMR tubes were labelled appropriately; A for acetonitrile, and O for toluene. 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 Exp107

Spectra

ONSCExp107A2 Raw data for JCAMP dx file ONSCExp107A2
ONSCExp107A3 Raw data for JCAMP dx file ONSCExp107A3
ONSCExp107O1 Raw data for JCAMP dx file ONSCExp107O1
ONSCExp107O2 Raw data for JCAMP dx file ONSCExp107O2
ONSCExp107O3 Raw data for JCAMP dx file ONSCExp107O3

Discussion

The solubility of p-fluorobenzoic acid in any non-aqueous solvent had not been previously reported at the time of this experiment. Thus the values generated by this experiment could not be compared to any other values but themselves. The solubility of p-toluenesulfonic acid in acetonitrile toluene yielded very uniform results [1]. However, the solubility of p-toluenesulfonic acid in toluene appeared to be very small and it was difficult to distinguish peaks on the NMR. Vial O1 appeared to be contaminated with water, thus trace amounts of p-toluenesulfonic acid probably dissolved in the water and appeared in the NMR spectrum. However, for vials O2 and O3 which were not contaminated, the peaks for p-toluenesulfonic acid did not appear, and thus it was assumed that there was no solute dissolved in the toluene and the solubility was zero.

Conclusion

The solubility of p-toluenesulfonic acid in acetonitrile was found to be 0.11M and 0.12M. The mean value was 0.11M and the standard deviation was 0.007.
The solubility of p-toluenesulfonic acid in toluene was found to be 0.00M. The mean value was 0.00M and the standard deviation was 0.00.

Log

2009-06-08
10:14--Added 200uL of toluene to 3 vials labeled O1, O2, and O3.
10:19--Added 200uL of acetonitrile to 3 vials labeled A1, A2, and A3.
10:22--After adding 4 small scoops of p-toluenesulfonic acid to vials O1, O2, and O3, the vials were capped and vortexed for approximately 10 seconds. This was repeated one time and the solution was found to be saturated.
10:31--After adding 3 small scoops of p-toluenesulfonic acid 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.
10:55--All vials A1, A2, A3, O1, O2, and O3 were set in a large beaker filled one-quarter with water and placed in the sonicator. The temperature was read at 26.0C and the timer was set to 30 minutes.
11:30--All vials were removed from the sonicator and set out to cool to room temperature in a water bath.
11:12--All vials were filtered, passing the contents of the vials through a pasteur pipette packed with cotton, thus allowing only the supernatant to pass through.
11:50--NMR tubes were prepared for each vial by taking the respective supernatants and added 500uL of CDCl3 to appropriately labeled NMR tubes.
11:55--NMR tubes O2, A1, and A3 all contained significant amounts of solid when mixed with CDCl3. It was assumed that the supernatant was super-saturated, thus when it cooled further, it released some solid p-toluenesulfonic acid. [No it jut means that the solute is less soluble in CDCl3 (check the solubility in CHCl3 at some point) - you would have to use DMSO-d6 in those cases. Either way the results are not usable if a precipitate comes out in the NMR tube JCB]

2009-06-10
9:15--The NMR spectra of all vials were taken on the 300MHz Varian instrument. A good spectra of vial A1 could not be obtained, perhaps due to the large amount of solid present in the tube.

References

[1] Solubility of p-toluenesulfonic acid in non-aqueous solvents

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