Researcher

Valentine Anyiam

Objective

Determination of the solubility of cinnamic acid in a series of glycol solvents: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and polyethylene glycol (PEG-400, average of 9 EG units) utilizing the shake flask method. The experiment would be carried out similar to the method published online by Beerbower, and with the use of a vortex genie.

Procedure

Prepare about a 1.5M solution of cinnamic acid in ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and polyethylene glycol (make sure to measure the exact mass of both the solute and the solvents). All five solutions must then be placed on top of vortexer to shake for about a day. Check the next day to see if the solutions have dissolved completely. If they have not, then prepare an NMR sample out of them for NMR analysis. If they have, then add some more cinnamic acid to each of the solutions that had dissolved completely and allow those solutions to shake on top of the vortex genie again for another day.

Results

Solubility Sheet 1
IMG_20120601_101106.jpg
Pic1: Glycol solutions with cinnamic acid after shaking for about a day. Only the ethylene and diethylene glycol solutions did not dissolve completely.
IMG_20120608_141004.jpg
Pic2: All of the solutions seem to be saturated.

Discussion

An NMR analysis of cinnamic acid in ethylene and diethylene glycol solvents revealed the concentration to be 0.369M and 0.837M respectively at 23C. This results contradicts the trend predicted of cinnamic acid in glycol solvents in that it was expected for cinnamic acid to have its highest solubility value within ethylene glycol and for the solubility to decrease as the number of carbon atoms on the glycol solvent increased. Instead it would seem as though the solubility increases to a certain extent and then possibly remains fairly constant with increasing number of carbon atoms on the glycol solvent. In order to confirm the NMR spectra obtained for cinnamic acid in triethylene, tetraethylene and polyethylene glycol still need to be converted into the appropriate file and uploaded unto the wiki.

Conclusion

The solubility of cinnamic acid in ethylene glycol and diethylene glycol were determined to be 0.37M and 0.84M respectively at 23C.

Log

2012-05-31

12:46- 0.4490g of cinnamic acid was added to a small vial labeled vial EGca.
13:03- 0.4495g of cinnamic acid was added to a small vial labeled vial DEGca.
13:08- 0.4541g of cinnamic acid was added to a small vial labeled vial TEGca.
13:12- 0.4496g of cinnamic acid was added to a small vial labeled vial TetraEGca.
13:15- 0.4527g of cinnamic acid was added to a small vial labeled vial PEGca.
13:21- 2.2491g of ethylene glycol was added to vial EGca.
13:24- 2.5084g of ethylene glycol was added to vial DEGca.
13:28- 2.4517g of ethylene glycol was added to vial TEGca.
13:31- 2.3817g of ethylene glycol was added to vial TetraEGca.
13:35- 2.3969g of ethylene glycol was added to vial PEGca.
13:47- All five solutions were sealed with screw caps, covered with parafilm covering and then duck taped on top of a vortex genie along with five other glycol solutions from EXP295 . The vortex genie was then set to shake at a setting of 2.

2012-06-01

10:04- The vortex genie was turned off. The triethylene, tetraethylene and polyethylene glycol solution with cinnamic acid seem to dissolved completely whereas the ethylene and diethylene glycol solutions with cinnamic acid did not.
10:11- Pic1 was taken of all five solutions.

2012-06-07

13:11- 0.294g of cinnamic acid was added into vial TEGca.
13:14- 0.295g of cinnamic acid was added into vial TetraEGca.
13:17- 0.292g of cinnamic acid was added into vial PEGca.
13:29- The cinnamic acid in ethylene glycol solution was filtered out into a small clean vial. A few microliters of it was then used to prepare an NMR sample with acetone-d-6 solvent.
13:31- The cinnamic acid in the diethylene glycol solution was filtered out into a small clean vial. A few microliters of it was then used to prepare an NMR sample with acetone-d-6 solvent.
16:02- The filtered cinnamic acid solutions were poured back into their respective vials.
16:09- All five solutions containing cinnamic were duck taped back on top of the vortex genie along with four other glycol solutions containing benzoic acid from EXP295. The vortex genie was set to shake at a setting of 2.
16:52- An NMR analysis was taken for the ethylene and diethylene glycol solutions containing cinnamic acid and were each saved as ONSCExp296NMREG1 and ONSCExp296NMRDEG1 respectively.

2012-06-08

14:05- The vortex genie was turned off.
14:10- Pic2 was taken of all five solutions containing cinnamic acid.

2012-06-11

13:27- The cinnamic acid in the triethylene, tetraethylene and polyethylene glycol solutions were filtered out into small separate clean vials. A few microliters of each sample was then used to prepare NMR samples with acetone-d-6 solvent of each of them.
13:57- An NMR analysis was taken for the triethylene, tetraethylene and polyethylene glycol solutions containing cinnamic acid and were each saved as ONSCExp296NMRTEG1, ONSCExp296NMRTetraEG1 and ONSCExp296NMRPEG1 respectively.