Researcher

Marshall Moritz

Objective

To generate a solubility-temperature curve for 4-nitrobenzaldehyde in acetonitrile, chloroform, THF, and toluene
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Procedure

Solutions of known concentration of 4-nitrobenzaldehyde in mixtures of acetonitrile, chloroform, THF, and toluene were made by weighing out a known amount of solvent, approximately one gram, in a tared half-dram vial. Weighed amounts of 4-nitrobenzaldehyde were added to each vial. Each vial was tightly capped and parafilmed. Vials were set in a thermostated water:ethylene glycol bath until the bath reached 46.0C. The bath was cooled, and the temperature at which each vial showed precipitate was recorded to create a solubility-temperature curve. An NMR spectra was taken of 4-nitrobenzaldehyde in pure THF and pure toluene to find the solubility at room temperature; vials were made with 200uL of solvent and enough solute such that the solutions were saturated after 30 minutes of sonication. The supernatants were dissolved in 500uL of CDCl3 and the NMR was taken on the 500MHz Varian instrument.

Results

Spreadsheet Exp114

Discussion

This experiment yielded results similar to those of Exp111, but with more variables and therefore 5 dimensions instead of 3. Though the five-dimensional surface could not be visualized, slices of the graph could be seen by setting three variables to zero and thus getting a three-dimensional plot of the three remaining variables. However, the entire 5-dimensional surface could be more accurately described with a regression (which will hopefully be done soon), which would generate an equation to predict the solubility of 4-nitrobenzaldehyde in any combination of the four solvents and at any temperature.

Conclusion


Log

2009-06-29
9:34--Mixtures of THF, toluene, acetonitrile, and chloroform were made in vials 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and 13. Each vial had a total of 0.5 grams of solvent.
10:56--After the solvent(s) were added, each vial was tightly capped and set aside.

2009-06-30
9:15--Various amounts of 4-nitrobenzaldehyde were weighed and carefully added to each vial such that each vial had a known concentration of approximately 0.65M. After the 4-nitrobenzaldehyde was added, each vial was tightly capped.
10:01--All vials were covered with parafilm to prevent any potential evaporation.
10:07--All vials were added to a thermostated 3:2 water:ethylene glycol bath and the bath was set to 45.0C.
10:32--The bath reached 45.0C, left vials in bath to equilibrate. At 45.0C, all vials showed saturated solutions. The following procedure describes the duration of the experiment: the bath was set to a temperature and the lid was removed from the bath so that all vials could be observed as the temperature fell. When the bath reached the desired temperature, it was left to equilibrate for approximately 5 minutes. After again looking for saturated solutions, the temperature of the bath could be lowered again.
10:45--All vials had clear, unsaturated solutions. The temperature was turned to 40.5C.
10:56--All vials were still unsaturated, The temperature was turned to 37.0C.
11:19--All vials were still unsaturated at 37.5C and the temperature was turned to 34.0C.
11:21--Vial 2 showed precipitate at 35.6C and was removed from the thermostated bath.
11:29--All remaining vials were unsaturated. The temperature was turned to 31.0C. This process continuted until vial 1 was removed at -12.9C.

References

Solubility of 4-nitrobenzaldehyde in non-aqueous solvents

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