Researcher

Marshall Moritz

Objective

To generate a solubility-temperature curve for 4-nitrobenzaldehyde in acetonitrile and chloroform.
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Procedure

Solutions of known concentration of 4-nitrobenzaldehyde in acetonitrile and chloroform 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, and a "flag" was attached to each vial by wrapping copper wire around the vial and attaching a labeled sticker to each vial. Vials were set in a thermostated water:ethylene glycol bath until the bath reached 45.0C. The bath was cooled, and the temperature at which each vial showed precipitate was recorded to create a solubility-temperature curve.

Results

Spreadsheet Exp111 NMR


Spreadsheet Exp111


Spreadsheet Exp111 Mixtures
EXP111.jpg

Spectra

ONSCExp111A2 Raw data for JCAMP dx file ONSCExp111A2
ONSCExp111A8 Raw data for JCAMP dx file ONSCExp111A8

Discussion

The NMR results show that the NMR technique is in fact very accurate, especially with relaxation times of 50 seconds for more accurate and sharper peaks. The concentration of A2, calculated to be 0.392M was found to be 0.38M by the NMR. Additionally, the saturated solution of 4-nitrobenzaldehyde in acetonitrile was found to be 0.95M at room temperature, which was 19.0C. This value seems to fit, as the concentration for a solution at 17.7C was found to be 0.908M.
The solubility-temperature graph generated from the data in this experiment yielded a saddle-shaped 3-dimensional plot with the 3 variables being temperature, solubility, and % mole fraction of chloroform in the mixtures. Though this is the maximum number of solvents that can be used to construct a graph in 3 dimensions, this experiment can be expanded to include more solvents and thus there exists another variable for each solvent used.

Conclusion

The experiment successfully yielded data that generated the 3-dimensional plot of solubility vs. temperature for a 2 solvent system. See Exp114 for a continuation of this experiment in a 4 solvent system.

Log

2009-06-22
10:36--Weighed out approximately one gram of acetonitrile in vials labeled with marker, A1, A2, A3, A4, A5, A6, A7, A8, A9, and A10 and one gram of chloroform in vials C1, C2, C3, C4, C5, C6, C7, and C8.
11:21--Various amounts of 4-nitrobenzaldehyde were weighed and carefully added to each vial such that each vial had a known concentration. After the 4-nitrobenzaldehyde was added, each vial was tightly capped.

2009-06-23
9:15--All vials were covered with parafilm to prevent any potential evaporation.
9:39--All vials were "flagged"; copper wire was wrapped around the neck of each vial and stickers, labeled appropriately for each vial (A1, A2, etc...) were attached to the end of the wire. This method prevented any marker from washing off and clearly labeled each vial to prevent any confusion.
10:07--All vials were added to a thermostated 3:2 water:ethylene glycol bath and the bath was set to 45.0C.
10:27--The bath reached 45.5C, left vials in bath to equilibrate. For 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. The sonicator was filled with a water/ethlyene glycol bath as well and vials were intermittently sonicated in the 35.0C sonicator.
11:01--All vials had clear, unsaturated solutions. The temperature was turned to 40.5C.
11:10--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 A10 showed precipitate at 36.5C and was removed from the thermostated bath.
11:23--Vial C8 showed precipitate at 35.5C 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 A1 was removed at -26.3C.

2009-06-24
9:28--Samples of vial A8, saturated at room temperature, and vial A2, at a known concentration to verify NMR technique, were dissolved in 500uL of CDCl3 in appropriately labeled NMR tubes..
9:38--NMR of A8 and A2 was taken on the 500MHz Varian instrument.
10:48--Mixtures of acetonitrile and chloroform were made in vials M1, M2, M3, M4, M5, M6, M7, M8, and M9, each with a total of 1 gram of solvent. Vials M1, M2, and M3 had 25:75 mixtures of acetonitrile:chloroform, vials M4, M5, and M6 were 50:50, and vials M7, M8, and M9 were 75:25.
11:26--Various amounts of 4-nitrobenzaldehyde were carefully weighed and added to vials M1, M2, M3, M4, M5, M6, M7, M8, and M9 so each vial had a known concentration. After the solute was added, each vial was tightly capped and vortexed for 10 seconds.

2009-06-25
9:19--All vials were covered with parafilm to prevent any potential evaporation.
9:39--All vials were "flagged"; copper wire was wrapped around the neck of each vial and stickers, labeled appropriately for each vial (M1, M2, etc...) were attached to the end of the wire. This method prevented any marker from washing off and clearly labeled each vial to prevent any confusion.
9:50--All vials were added to a thermostated 3:2 water:ethylene glycol bath and the bath was set to 40.0C.
10:23--The bath reached 40.0C, left vials in bath to equilibrate. For 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.
10:38--All vials had clear, unsaturated solutions. The temperature was turned to 30.0C
10:34--All vials were still unsaturated, The temperature was turned to 28.0C
10:42--All vials were still unsaturated, the temperature was turned to 24.0C
10:43--Vial M3 showed precipitate at 27.7C and was removed from the thermostated bath.
11:44--Vial M6 showed precipitate at 27.0C and was removed from the thermostated bath.
10:47--Vial M9 showed precipitate at 25.6C and was removed from the thermostated bath.
10:48--Bath reheated to 32.0C, all vials were unsaturated, double checked temperatures for vials M3, M6, M9.
12:51--All remaining vials were unsaturated. The temperature was turned to 19.0C. This process continuted until vial M4 precipitated at -24.5C.

References

Solubility of 4-nitrobenzaldehyde in non-aqueous solvents

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