1 2 3 4



Researcher

Evan Curtin

Objective

To determine the solubility of Salicylideneaniline (1) N-(4-Dimethylaminobenzylidene)aniline (2) N-(4-Methoxybenzylidene)aniline (3) and N-Vanillylidene aniline (4) in a 90/10 (v/v) mixture of ethanol and water.

Procedure

Results

SAMS spreadsheet
SAMS2 (Contains calculation for ratios of aldehyde in the imines used)
Volume Calculation Sheet

The solubility in a 90/10 (v/v) mixture of ethanol and water for the compounds along with the molar percent of aldehyde to imine is:
Salicylideneaniline : 0.5139 M, 10.92%
N-(4-Dimethylaminobenzylidene)aniline : 0.0918 M, 11.30%
N-(4-Methoxybenzylidene)aniline : 0.8784 M, 16.87%
Sample 1



Sample 2



Sample 3



Discussion

In each case, the imines hydrolyzed to their respective aldehydes and amines. The amount of aldehyde was quantified by comparing the concentration of the aldehyde to the imine (using the integration of the peaks at 9.6-10ppm and 8.2-8.8ppm, respectively)(calculations). Samples 1 and 2 contained a 12% ratio of aldehyde to imine, while sample 3 had 20%. In UCexp269 (the source of samples 1, 2 and 3), there was a 2.71% aldehyde to imine ratio for N-(4-Dimethylaminobenzylidene)aniline, and there was no detectable amount of aldehyde in the other two samples(calculations). In all cases, the imine hydrolyzed more in the ethanol/water solution.

[Are these results expected from Godoy2005 ? JCB]
The predicted solubilities in a 90/10 (vol) ethanol/water mixture for salicaldehyde, N-(4-Dimethylaminobenzylidene)aniline, and N-(4-Methoxybenzylidene)aniline are 0.115M, 0.055M and 0.012M, respectively [only compare to Abraham predictions JCB]. In comparison, the solubilities determined in this experiment were 0.5175, 0.0918 and 0.9009.

Conclusion

The attempt at finding the solubility of imines in the 90/10 ethanol water mixture was hindered by hydrolysis of the imine to the aldehyde. Nevertheless since hydrolysis was < 17%, the values were used and recorded in the solsum sheet.

Log

2011-07-08

10:30 - Turned bath temperature to 40°C, current temperature 24C
10:34 - Weighed ethanol and water, (14.2074g ethanol, 2g water). Mixed in a 20mL screw cap tube. Put the cap on.
10:53 - Weighed out each sample into 1 dram screw cap vials. (1) is 269-1, (2) is 269-2, (3) is 269-3, and (4) is 268. The samples weighed: (1) 0.2994g, (2) 0.2566g, (3) 0.3151g, (4) 0.2658g.
11:03 - Weighed the ethanol/water mixture into each sample. (1) 0.7998g, (2) 0.8470g, (3) 0.7846g, (4) 0.9147g
11:09 - Covered the vials in parafilm, and added to bath (temperature now 45C)
11:40 - 1 and 3 dissolved completely, bath temperature is 45C
11:46 - Decanted 2 and 4 into new vials, set all samples on counter at RT (25C).
11:48 - 1 had precipitate, sonicated all samples. 2 formed precipitated. 3 Formed layers (small viscous layer formed at the bottom). 4 had no visible change.
12:16 - The layers dissappeared in 3 and it is now one clear solution. Sample 1 is now all liquid, but there are layers present.
12:17 - Took samples from the solutions of 1, 2 and 3. Added CDCl3. 1 and 2 became cloudy. They remained cloudy after sonication. Added 1-3 drops of DMSO-d6 to each, and they became clear.
12:26 - Added to NMR tubes.
12:55 - Took HNMR using varian 500MHz NMR.
[Even if 4 did not give a precipitate at room temp still get an NMR to evaluate imine hydrolysis JCB]