Researcher

Jenna Mancinelli

Objective

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

Procedure

The following seven solutions are prepared each with 200 ul of the chosen solvent and enough solute so that that mixture is saturated:
(1) benzoic acid in methanol
(2) phenanthrene-9-carboxaldehyde in acetonitrile
(3) p-toluenesulfonic acid in ethanol
(4) 4-methoxyphenylacetic acid in methanol
(5) nicotinic acid in methanol
(6) B,B-dimethylacrylic acid in methanol
(7) 4-acetamidobenzoic acid in methanol
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

PIctures
ONSCExp136-1
SAMS Spreadsheet

ONSCExp136-1A
ONSCExp136-2A
ONSCExp136-3A
ONSCExp136-4A
ONSCExp136-5A
ONSCExp136-6A
ONSCExp136-7A



Discussion


Solute
Avg Solubility (M)
SD
Benzoic acid
2.8215
0.2407
Phenanthrene-9-carboxaldehyde
0.1537
0.045
4-methoxyphenylacetic acid
2.4767
0.2311
Nicotinic acid
0.0633
0.0047
The solubilities obtained for benzoic acid, phenanthrene-9-carboxaldehyde, and 4-methoxyphenylacetic acid are all consistent with previous findings. I have found benzoic acid to have a solubility of 2.97 M which is within the standard deviation of the average 2.8215 M. The obtained solubility of phenanthrene-9-carboxaldehyde was 0.15 M which almost exactly matches the 0.1537 M average. Additionally, the solubility obtained for 4-methoxyphenylacetic acid was 2.57 M which is within the standard deviation of the average 2.4767 M.

No reliable solubilites were obtained for nicotinic acid or 4-acetamidobenzoic acid, because these samples did not go into solution with the CDCl3 in the NMR tubes. For this reason, the numbers collected should not be considered reliable.

No results for p-toluenesulfonic acid in ethanol or B,B-dimethylacrylic acid in methanol have been previously recorded. For this reason, the solubilities I have obtained for these samples cannot be compared to other data.


Conclusion

The solubilities for six solutes in different solvents have been determined by H NMR.
Solute
Solvent
Solubility (M)
benzoic acid
methanol
2.97
phenanthrene-9-carboxaldehyde
acetonitrile
0.15
p-toluenesulfonic acid
ethanol
4.69
4-methoxyphenylacetic acid
methanol
2.57
B,B-dimethylacrylic acid
methanol
4.73
4-acetamidobenzoic acid
methanol
0.52

Log


2009-08-20
10:20 Prepared seven vials each containing 200 ul of the appropriate solvent and enough of the chosen solute so that the solutions appeared saturated, with the solute visible in the vials.
13:35 Took picture ONSCExp136-1 of seven vials to display saturation of solutions.
13:37 Placed all vials into heating-cooling thermostat with 60% water and propylene glycol bath that had been previously set to 45C.
14:22 Lowered temperature of bath to 25C. While still at 45C, but after having been in the bath for 45 minutes, vials 4 (4-methoxyphenylacetic acid) and 6 (B,B-dimethylacrylic acid) appear as unsaturated solutions with no observable solute. The remaining five vials all appear to have more saturated solutions than before being put into the bath. The amount of solvent appeared to have decreased in these vials.
2009-08-24
11:30 Removed the sample vials from the bath.
11:40 Transferred ~100uL of the supernatant from each vial in to clean NMR tubes with 700uL CDCl3 in them. Supernatants from vials (5) and (7) did not dissolve in CDCl3 (formed two layers)
15:30 Obtained HNMR of the solutions ..labeled ONSCExp1A to 7A.