Objective

To ascertain the solubility of 2-phenylbutyric acid in toluene, THF, DMSO by NMR spectroscopy.

Procedure

Saturated solutions of 2-phenylbutyric acid were prepared in toluene, THF, and DMSO. The solutions were prepared by mixing together the solute and 150μL of the solvent into a vial. With each subsequent addition of solute, there were bouts of vortexing. Once the solutions showed an excess of solute, the vials were sonicated, using a Branson 1510 instrument, for 30 minutes. Solutions were then left to equilibrate. 100μL of the supernatants were micropipetted out and then dissolved into NMR tubes containing 900μL of deuterated chloroform (CDCl3) Proton NMR readings of the solutions are obtained with the use of a 500MHz instrument.

Results

Sample
Solvent
Solute
HNMR
HNMR Raw Data
Solubility (M)
1
Toluene
2-phenylbutyric acid
HNMR
2-phbutyricacid-toluene-SAMS.jdx
5.35
2
THF
2-phenylbutyric acid
HNMR
2-phbutyricacid-THF-SAMS.jdx
5.96
3
DMSO
2-phenylbutyric acid
HNMR
2-phbutyricacid-DMSO-SAMS.jdx
5.97

Image of the supernatants post sonication
Image of the supernatants post equilibriation

Spreadsheet




Discussion

Saturated solutions in each solvent was obtained. This was verified by observation of solid solute contained within the sample vials after the sonication process. Therefore, the NMR spectra obtained could be held in confidence that the spectra was from a saturated solution, and that solubilites obtained from the spectra were validated.
Also of possible interest, when drawing-up these solutions it was observed the an endothermic reaction occurred (the vials grew noticeably colder to the touch upon addition of the solute to the solvents).

To help with the standardization of the procedure, the temperature of the water within the sonicator should be taken before and after the sonication process as occurred. Furthermore, a stock amount of water should be kept at a temperature perhaps of 18°C to be used as the starting temperature for each sonication process. Also, once the sonication process is completed, the vials should be allowed to equilibrate in a volume of that stock water that is kept at 18°C. Lastly, the temperature of the laboratory should be noted before solutions of the supernatant and the deuterated solvent are formulated for the NMR analysis.

When doing a query on 2-phenylbutyric acid, solubility results are retrieved from this experiment as well as Exp022. However, upon review of Exp022, it can be seen that an optically active 2-phenylbutyric acid was used [(+)-2-phenylbutyric acid]; therefore it must be stated that both carboxylic acids are not of the same source. The 2-phenylbutyric acid used for this experiment presents in a solid crystalline form, while the (+)-2-phenylbutyric acid was a viscous liquid.

ONSC_Exp083_2-phenylbutyric_acid_&_(+)-2-phenylbutyric_acid.jpg

Nonetheless, both forms are of the same compound, which was verified by taking an HNMR spectra of them both.

2-phenylbutyric acid (sample was dissolved in CDCl3) (This spectra has also be deposited on Chemspider, as the spectra for this compound was missing)
(+)-2-phenylbutyric acid (sample was dissolved in CDCl3)

Conclusion

The solubility of 2-phenylbutyric acid has been determined in toluene, THF, and DMSO. The obtained data shows that 2-phenylbutyric acid is indeed capable of making 2M solutions for the Ugi product.


Log

(includes Observations)

2009-04-22

17:16 Ambient temperature within the lab was measured to be 22°C.
17:20 A saturated solution of 2-phenylbutyric acid in toluene was made by adding the solute to 150μL of toluene solvent in a vial labeled "toluene". Vortexed the vial briefly in-between additions, till the solute visibly collected at the bottom of the vial. With every subsequent addition of solute to the solution (when vortexing after adding some solute to the solution, the solute would dissolve into the solution; if this occurred, there is a need to add more solute, so that once the solution is vortexed, there still remains to be some solute that can not be dissolved into the solution, which is used as a presumption that saturation has been reached, later confirmed after the sonication process) the volume of the solution was observed to increase, this can be taken to mean that the solute is perhaps quite soluble in the solvent; because the solvent is able to dissolve a considerably great amount of the solute . Also, the reaction appeared to be endothermic, observed by the vial feeling cold to the touch with addition of solute to the solvent.[good observation - that is interesting JCB]
17:24 A saturated solution of 2-phenylbutyric acid in THF was made by adding the solute to 150μL of THF in a vial labeled "THF". The vial was vortexed briefly in between additions, till the solute was seen to collect at the bottom of the vial. The volume of this solution also greatly increased and appeared to be an endothermic reaction.

17:29 A saturated solution of 2-phenylbutyric acid in DMSO was made by adding the solute to 150μL of DMSO in a vial labeled "DMSO". Vortexed the vial briefly in between additions, till the solute visibly collected at the bottom of the vial. The volume of this solution also greatly increased and appeared to be an endothermic reaction..
17:37 Sonicated all 3 vials. Starting temperature recorded to be 18
°C.
18:10 It was observed that there was still solute that remained collected at the bottom of the vial. End temperature of sonicator recorded to be 31°C. Obtained an image of post-sonicated vials. Vials were left to equilibrate

2009-04-23

16:10-16:20 Obtained image of post-equilibrated vials.
17:01 Micropipetted 900μL of deuterated chloroform into 3 NMR tubes, labeled "toluene", "THF", and "DMSO."
17:05 Micropipetted 100μL of the supernatant from the
"toluene" vial into its respective NMR tube. Mixed.
17:06 Micropipetted 100μL of the supernatant from the "THF" vial into its appropriate NMR tube. Mixed.
17:07 Micropipetted 100μL of the supernatant from the "DMSO" vial into its respective NMR tube. Mixed.
17:10 Obtained NMR spectra using the 500MHz Varian instrument.


References


Solubility of 2-phenylbutyric acid in toluene (Solubility data viewer)
Solubility of 2-phenylbutyric acid in THF (Solubility data viewer)
Solubility of 2-phenylbutyric acid in DMSO (Solubility data viewer)

Compound
Inchi Key
Inchi
2-phenylbutyric acid
OFJWFSNDPCAWDK-UHFFFAOYAE
InChI=1/C10H12O2/c1-2-9(10(11)12)8-6-4-3-5-7-8/h3-7,9H,2H2,1H3,(H,11,12)
Toluene
YXFVVABEGXRONW-UHFFFAOYAT
InChI=1/C7H8/c1-7-5-3-2-4-6-7/h2-6H,1H3
THF
WYURNTSHIVDZCO-UHFFFAOYAI
InChI=1/C4H8O/c1-2-4-5-3-1/h1-4H2
DMSO
IAZDPXIOMUYVGZ-UHFFFAOYAR
InChI=1/C2H6OS/c1-4(2)3/h1-2H3