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list of experiments
Solubility book (3rd Edn)
1A from UCExp262
To determine the solubility of 1A from
) in ethanol and hexane and benzalaniline (from
) in ethanol by
SAMS NMR method
Make saturated solutions of the solute in the solvents of interest. Do this by mixing the solute into the solvent. Heat to around 40-45C. If all solid dissolved, let sit on counter, but if there is still solid remaining, decant immediately into a clean container and let the supernatant sit on counter. Let solution stand to equilibriate. If the solid precipitates, decant the supernatant. This is a saturated solution. However, if there is no solid, try to precipitate solid using a sonicator. If there is still no precipitate, evaporate solvent slowly using air, sonicating from time to time to avoid supersaturation (be careful that the temperature doesn't drop too low). Once solid precipitates, decant the solution. This is saturated.
Take some saturated solution (100-300 microliters). Add deuterated solvent to the solution (a few hundred microliters). Add the new solution to an NMR tube so that the solution fills 5cm in the tube. Take the HNMR spectrum of the solution. Use webservice to compare the solute and solvent peaks.
The solubility in ethanol for the compounds is
For Benzalaniline: 1.3 M
For UCExp262-1A: 0.07 M
Calculations for solubility data.
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The solution of benzalaniline (sample 1) had an aldehyde peak at 9.95ppm. The ratio of the imine peak at 8.42ppm to this peak is 9.96:1. (integration values are 6.58 and 0.66). However, the HNMR of
-2D had no noticeable aldehyde peak. The imine must have been hydrolyzed at some point. The sample was exposed to air for a long period of time and there could be water in the air that caused the hydrolysis.
The spectrum for the solution of N-vanillylidene aniline (
-1A) has peaks that are highly distorted. The appearance of peaks around 11 and 10 ppm are probably a result of this distortion. The values for this sample are invalid.
Solubilities were determined for the two compounds in ethanol. However, the NMRs show that in both cases, the values are not accurate.
12:27 - Inspected
after being left to evaporate at room temperature. Precipitate formed.
12:45 - Made solution of hexane and 1A from
, now called 2. (Benzalaniline in ethanol is 1).
13:24 - Solution (2) never fully dissolved, discarded and made a new solution of lower concentration with the same materials (3).
13:40 - Solution (3) never fully dissolved, discarded and made a new solution of lower concentration with the same materials (4). 4 again didn't dissolve; solubility is most likely very low.
14:29 - Made a solution of 1a from
and ethanol (labeled 5). Heated solution in 50C bath until all dissolved, this took less than 2 minutes. Allowed to cool at RT for about 5 minutes, sonicated. Precipitate formed.
14:45 - Decanted the supernatant from 5 and mixed with CDCl3 and put in NMR tube. Added solution 1 to NMR tube along with CDCl3. No new precipitates formed. Took NMR of sample using 300MHz varian.
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