Researcher

Tim Bohinski

Objective

To measure the solubility of p-nitrobenzaldehyde in different solvents.. For a justification of this project see here.

Procedure

Saturated solutions are made of PNBA (link to ChemSpider) in different solvents by charging a one dram vail with 900ul of the solvent. PNBA is then added until the solution is saturated. Each vial is vortexed for 30s. Also each vial is centrifuged for 1-2minutes. 300ul of the liquor is then pipetted into half dram preweighed vials. The solution is weighed and entered into the speedvac. The solution is then reweighed after all of the liquid has evaporated off. The results can be found in the Spreadsheet.

Results

The results can be found in the Spreadsheet
Pictures will posted as soon as camera software gets fixed via Khalid. Failure of camera to retrieve pictures.
PNBA in acetonitrile:1.06M
PNBA in methanol: 0.398M
PNBA in chloroform: 1.08M
PNBA in ethanol: 0.131M
PNBA in toluene: 0.374M
Other findings using the same solute and solvents can be found in this article. Private Access.

Discussion

Vial 3b was hard to charge with solution since some solute may have entered the pipet. Spreadsheet. Previous runs showed a decrease in pressure during Exp208. For Exp212 a new pump in the speedvac was used and the pressure didn't change during the experiment. However powders were still obtained from the saturated solutions. Thus a drop in pressure in the speedvac doesn't mean powders can't be obtained.
The solutions may have to be held on the vortex longer to see if any further dissovling occurs, since the only result that matches with other findings is when chloroform was the solvent.
In Exp208 vials that were designated for PNBA was aborted since it was believed that enough solute was available. I wanted to see experimentally if there was enough PNBA, and there was since this experiment was performed.
PNBA as found in the published papers is as follows:
PNBA in acetonitrile: 1.350M
PNBA in methanol: 1.23M
PNBA in chloroform: 1.08M
PNBA in ethanol: 0.376M
PNBA in toluene: 0.467M

Conclusion

Solutions will be vortexed longer to see if the saturated solutions' concentration can be increased.
[Ethanol and methanol values marked as "solute reacts with solvent" since hemiacetal likely forms JCB]

Log

2008-10-31
11:00 Charged one dram vials with 900ul of each solvent
11:10 Charged each solvent with PNBA.
11:15 Vortexed each for 30 seconds, making sure solution was saturated.
11:20 Centrigued each solution for one minute
11:21 Labeled half dram vials
11:25 Weighed half dram vials.
11:37 Picture was taken of vials. (212p1)
11:40 Pippetted 300ul of each saturated solution into duplicated half dram vials
11:50 Weighed the half dram vials
12:00 Took picture of vials. (212p2)
12:05 Entered half dram vials into speedvac. Pressure (5Torr)
13:00 Removed from speedvac, and reweighed.
14:00 Took a picture of powders in vial. (212p3)

References

Solubility of 4-nitrobenzaldehyde in methanol