Researcher

Jenna Mancinelli

Objective

To determine the solubilities of four solutes in different solvents by H NMR.

Procedure

The following six solutions are prepared each with 200 ul of the chosen solvent and enough solute so that that mixture is saturated:
(1) 3,4-(methylenedioxy)phenylacetic acid in acetonitrile
(2) salicylic acid in toluene
(3) salicylic acidin chloroform
(4) salicylic acid in dichloromethane
(5) phthalic acid in chloroform
(6) trans-cinnamic acid in acetone
Once solutions are prepared, they are placed into a heating-cooling thermostat with 60% water and propylene glycol bath set to 45C. After 45 minutes, the temperature of the bath is lowered to 25C. The vials remain in the bath set to 25C for an additional 45 minutes. An H NMR is obtained for all the vials.

Results


SAMS Spreadsheet


Discussion

Using the data obtained through H NMR, the solubilities of three out of the four solutes were able to be determined. 3,4-(methylenedioxy)phenylacetic acid in acetonitrile was determined to have a solubility of 0.1 M. Salicylic acid in toluene has a solubility of 0.11 M, while when in dichloromethane it was found to have a solubility of 0.15 M. The solubility of phthalic acid in chloroform was determined to be 0.51 M. To my knowledge no previous solubility measurements of these same solute-solvent mixtures have been recorded, and thus no comparisons can be made at this time.

H NMR spectra of the mixtures of salicylic acid in chloroform and trans-cinnamic acid in acetone were not able to be obtained. The salicylic acid in chloroform did not produce a clear supernatant upon centrifugation, and therefore no pure sample could be extracted and placed into an NMR tube. The trans-cinnamic acid in acetone showed no remaining solvent after being in the bath at 25C. Both of these samples will need to be redone in order to obtain accurate spectra and solubility measurements.

Conclusion

The solubilities of three solutes in different solvents have been determined by H NMR.
Solute
Solvent
Solubility (M)
3,4-(methlenedioxy)phenylacetic acid
acetonitrile
0.1
salicylic acid
toluene
0.11
salicylic acid
dichloromethane
0.15
phthalic acid
chloroform
0.51

Log


2009-08-27
15:20 Labeled six vials Vial 1 - Vial 6
15:40 Added approximately 200 ul of the appropriate solvent to each vial
15:55 Added enough of the appropriate solute to each vial so that a saturated solution was prepared.
16:15 Parafilmed tightly, vortexed for 15 seconds, and tagged each vial.
16:25 Placed all vials into heating-cooling thermostat with 60% water and propylene glycol bath that had been previously set to 45C.
16:55 Lowered temperature of bath to 25C.
17:40 Removed samples from bath. Vial 6 showed no visible solvent. Centrifuged vials 1 through 5. Vial 3 did not show two distinct layers after centrifuging.
18:00 H NMR obtained for vials 1, 2, 4 and 5.