Researcher

Matthew McBride

Objective

To determine the solubility of trans-dibenzalacetone (Product A from EXP300) in Ethyl Acetate, Ethanol, and Hexanes using the Shake Method and SAMS HNMR.

Procedure

A small amount of the trans-dibenzalacetone (approximately 0.1 g) was placed in each of three 1-dram screw cap vials. Each solvent was added to one of the vials. The vials were placed on the shake plate for 24 hours to create saturated solution. The supernatant was then analyzed by SAMS HNMR to measure solubility. If no crystals were visible in the vial, then additional crystals were added. The vials were placed back on the shake plate for an additional 24 hours (48 hours in total). The supernatant was once again analyzed by HNMR to determine solubility. The solubility values from 24 hours and 48 hours were compared to be sure the solution was indeed saturated. A saturated solution will give equal solubility values.

Results

SAMS Sheet 1 for Vial A - solubility in ethyl acetate:
24 hours: 0.655M at 23°C
48 hours: 0.624M at 23°C
SAMS Sheet 2 for Vial B - solubility in ethanol:
24 hours: 0.070M at 21.5°C
48 hours: 0.098M at 23°C
SAMS Sheet 3 for Vial C - solubility in n-hexane:
24 hours: 0.079M at 21.5°C
HNMR Spectrum of just the CDCl3 used for this experiment.

Discussion

The close agreement of the solubility measurements in ethyl acetate indicate that the solubility is 0.6M. For ethanol, the measurements are also very close and indicate a solubility around 0.8M. For n-hexanes, there is confusion regarding whether the solvent is n-hexane or just hexanes. The spectrum is a bit messy from 0.8-1.6 ppm and does not clearly show n-hexane. Additionally, only a 24 hour measurement could be made, because all of the liquid in the vial escaped during the second day of mixing. This was possible because the vials were placed on their sides to be secured to the shake plate. In the future, the vials will be secured in a vertical position to prevent any of the liquid from escaping. The lack of certainty that the solvent sued was n-hexane and the inability to obtained a 48 hour measurement requires that this solubility be remeasured.

Conclusion

The solubility of trans-dibenzalacetone in ethyl acetate is 0.6M. The solubility in ethanol is 0.08M. Initial testing indicates that the solubility of trans-dibenzalacetone acetone in n-hexanes could be around 0.079M.

Log

2012-06-26

16:05 0.1145 g of the trans-dibenzalacetone from EXP300 was added to a [[#|screw cap]] 1-dram vial (Vial A). 0.[[#|1000]] g of the crystals were added to Vial B. 0.0995 g of the crystals were added to Vial C.
16:17 0.6 mL of ethyl acetate was added to Vial A. Some of the crystals dissolved into the solution immediately, but some crystals were still visible in the solution.
16:21 0.6 mL of ethanol was added to Vial B. A small amount of the crystals entered the solution, but most of the crystals were still visible.
16:24 0.6 mL of n-hexane were added to Vial C. Most of the crystals were still visible.
16:29 A [[#|screw cap]] was placed on each vial and sealed with parafilm. The three vials were taped together and secured onto the vortex. The vortex was turned on to level two and continuously shook the vials to mix the solutions. Picture #1 was taken.

2012-06-27

9:52 The three vials were removed from the vortex shake plate and a thermometer was immediately placed in Vial C to test the temperature. The temperature was 89°F (31.6°C). All of the crystals had entered the solution in Vial A (ethyl acetate). Crystals were visible in both Vial B (ethanol) and Vial C (hexanes). Vials B and C were placed on the lab bench at room temperature (lab temperature was 21.5°C) to allow the crystals to settle below the supernatant.
10:05 0.0230 g of trans-dibenzalacetone was added to Vial A and the vial was placed back on the shake plate. The vial was sealed with a screw cap and parafilm.
10:50 CDCl3 was placed in the inner NMR tube. Picture #2 was taken of Vials B and C.
11:01 Approximately 0.5 mL of the supernatant from Vial B was added into the outer NMR tube. The inner NMR tube containing the reference (CDCl3) was placed into the NMR tube holding the sample.
11:10 The solution from Vial B was analyzed by 500MHz HNMR to determine the solubility. The file of the spectrum was named ONSEXP301VialB.
16:45 The supernatant used for the NMR analysis from Vial B was placed back into Vial B. A few drops of this supernatant was added to 0.5 mL of CDCl3 and added to an NMR tube. A few drops of the supernatant from Vial C was added to 0.5 mL of CDCl3 and added to an NMR tube. 0.5 mL of just CDCl3 was added to an NMR tube.
16:58 Crystals were visible in Vials A, B and C when Vials B and C were placed back on the shake plate.
20:01 The Vial B sample, the Vial C sample, and the pure CDCl3 sample was analyzed by 500MHz HNMR. The Vial B and C samples were after 24 hours of mixing on the shake plate.

2012-06-28

12:49 Removed the three vials from the shake plate. Lab temperature was 23°C. Crystals were visible in each vial, but no liquid was present in Vial C. The liquid must have leaked out. No supernatant could be obtained from Vial C.
13:04 A few drops of the supernatant from Vial A and Vial B were each added to CDCl3 and placed in an NMR tube. Each sample was analyzed by 500MHz HNMR. The sample from Vial A was following 24 hours of shaking and the sample form Vial B was after 48 hours of shaking. Vial A was then placed back on the shake plate.

2012-06-29

9:42 Vial A was removed from the shake plate and placed on the lab counter to cool and allow the crystals to settle. The lab temperature was 23°C. A small amount of the liquid seemed to have escaped from the vial. The vials should be secured in a vertical position on the shake plate to prevent the solvent form leaking.
9:49 Added a few drops of the supernatant from Vial A to CDCl3 and added to a NMR tube.
10:16 The sample from Vial A following 48 hours of mixing was analyzed by 500MHz HNMR.