Researcher

Marshall Moritz

Objective

To determine the solubility of 2-chloro-5-nitrobenzaldehyde in 6 different solvents: ethanol, methanol, acetonitrile, THF, DMSO, and toluene by NMR spectropscopy.

Procedure

Saturated solutions of 2-chloro-5-nitrobenzaldehyde in 6 different solvents were prepared by adding excess solute to 300uL of solvent in a one-dram vial. The vials were vortexed for approximately 10 seconds and if necessary, more solute was added until after vortexing, precipitate remained on the bottom of the vial. The vials were sonicated until solid remained for 30 minutes of consecutive sonication. The supernatant was then removed from the vials by Pasteur pipette. NMR tubes were labelled appropriately; E for ethanol, M for methanol, A for acetonitrile, T for THF, D for DMSO, and O for toluene. 2-3 drops of the supernatant were added to 500uL of CDCl3 in the appropriate NMR tubes. An NMR of each sample was taken on the 300MHz Varian instrument.

Results


Spreadsheet Exp105

Spectra

ONSCExp105A1 Raw data for JCAMP dx file ONSCExp105A1
ONSCExp105A2 Raw data for JCAMP dx file ONSCExp105A2
ONSCExp105A3 Raw data for JCAMP dx file ONSCExp105A3
ONSCExp105D1 Raw data for JCAMP dx file ONSCExp105D1
ONSCExp105D2 Raw data for JCAMP dx file ONSCExp105D2
ONSCExp105D3 Raw data for JCAMP dx file ONSCExp105D3
ONSCExp105E1 Raw data for JCAMP dx file ONSCExp105E1
ONSCExp105E2 Raw data for JCAMP dx file ONSCExp105E2
ONSCExp105E3 Raw data for JCAMP dx file ONSCExp105E3
ONSCExp105M3 Raw data for JCAMP dx file ONSCExp105M3
ONSCExp105O1 Raw data for JCAMP dx file ONSCExp105O1
ONSCExp105O2 Raw data for JCAMP dx file ONSCExp105O2
ONSCExp105O3 Raw data for JCAMP dx file ONSCExp105O3
ONSCExp105T1 Raw data for JCAMP dx file ONSCExp105T1
ONSCExp105T2 Raw data for JCAMP dx file ONSCExp105T2
ONSCExp105T3 Raw data for JCAMP dx file ONSCExp105T3

Discussion

The solubility of 2-chloro-5-nitrobenzaldehyde in several solvents had been previously measured before this experiment, thus the values generated by this experiment were verified when compared to other experiments using the same solvent and solute. Exp208 reported a concentration value of 2.83M for 2-chloro-5-nitrobenzaldehyde in THF [1], which was in agreement with the values in this experiment, 2.72M, 2.81M, and 2.79M. The proximity of solubilities from two separate experiments, plus 3 trials in the same experiment rules out the possibility of systematic errors, and the experiment was successful.

The solubility of 2-chloro-5-nitrobenzaldehyde in acetonitrile had also been measured in EXP069 and exp208 and the values in this experiment were not in agreement with either of the previous experiments [2]. Compared to values of 1.99M, 2.15M, and 1.97M from this experiment, the solubility in was reported as 2.30M from EXP069 and 3.12 from exp208. The log from EXP069 shows the vial was not sonicated and may have been improperly vortexed. It is also unclear if/how precipitate was separated from the supernatant, thus the value from this experiment is somewhat unreliable. The log from exp208 shows some problems with evaporation when the samples were put in the speed-vac, so evaporation of the solvent may have generated a higher solute-to-solvent ratio, thus the higher concentration.[Actually the evaporation problem can only give rise to underestimated values. The hypothesis that NMR is significantly underintegrating because only aldehyde and aromatic peaks are available needs to be looked at. You could try to make a 0.6M solution in methanol and do SAMS on that JCB] The same experiments also reported values of 2-chloro-5-nitrobenzaldehyde in toluene and again there was significant disagreement [3]. EXP069 and exp208 showed values of 2.14M and 2.00M respectively, while this experiment had concentrations of 1.55, 1.47, and 1.55M. As the other experiments were again too high, perhaps there was a difference in the room temperature during the labs.

EXP069 and exp208 also gave concentrations of 2-chloro-5-nitrobenzaldehyde in ethanol [4]. There was again confusion with all values from those experiments and this experiment as the results were scattered. This experiment yielded values of 0.37, 0.30, and 0.22, with a standard deviation of just 0.075. Other reported concentrations were 0.12M from EXP069 and 0.52M from exp208. The values from this experiment still fall near the mean and median of all reported values, so it is likely they are fairly accurate. EXP069, Exp033, and exp205 reported values for methanol as well [5], and they were again fairly scattered, with values of 0.18M, 0.27M, and 0.78M respectively, while this experiment generated a concentration of 0.31M. This value was in close proximity to EXP069 and Exp033, leaving 0.78M as a statistical outlier. However, it must be considered that the vials of 2-chloro-5-nitrobenzaldehyde in methanol had problems during sonication as the lids repeatedly popped off and methanol evaporated from the vials. This happened repeatedly, thus only one value was reported from this experiment, so it is difficult to say whether or not it is accurate, even with the values from the other experiments because they are not clustered.

The concentration of 2-chloro-5-nitrobenzaldehyde in DMSO had not been previously reported at the time of this experiment. Thus the values generated by this experiment could not be compared to any other values but themselves [6]. There were no statistical anomalies in the solubility of 2-chloro-5-nitrobenzaldehyde in THF, and the data set was very uniform. Thus, excluding possible systematic errors, the experiment generated good results.

Conclusion

The solubility of 2-chloro-5-nitrobenzaldehyde in acetonitrile was found to be 1.99M, 2.15M, and 1.97M. The mean value was 2.036M and the standard deviation was 0.098.
The solubility of 2-chloro-5-nitrobenzaldehyde in DMSO was found to be 2.84M, 2.97M, and 2.98M. The mean value was 2.93M and the standard deviation was 0.078.
The solubility of 2-chloro-5-nitrobenzaldehyde in ethanol was found to be 0.37M, 0.30M, and 0.22M. The mean value was 0.296M and the standard deviation was 0.075.
The solubility of 2-chloro-5-nitrobenzaldehyde in methanol was found to be 0.31M. The mean value was 0.31M and the standard deviation was 0.00.
The solubility of 2-chloro-5-nitrobenzaldehyde in toluene was found to be 1.55M, 1.47M, and 1.55M. The mean value was 1.523 and the standard deviation was 0.462
The solubility of 2-chloro-5-nitrobenzaldehyde in THF was found to be 2.72M, 2.81M, and 2.79M. The mean value was 2.776M and the standard deviation was 0.051.

Log

2009-06-02
10:18--Added 300uL of DMSO to 3 vials labeled D1, D2, and D3.
10:21--Added 300uL of methanol to 3 vials labeled M1, M2, and M3.
10:25--Added 300uL of toluene to 3 vials labeled O1, O2, and O3.
10:27--Added 300uL of THF to 3 vials labeled T1, T2, and T3.
10:29--Added 300uL of acetonitrile to 3 vials labeled A1, A2, and A3.
10:31--Added 300uL of ethanol to 3 vials labeled E1, E2, and E3.
10:34--After adding 3 small scoops of 2-chloro-5-nitrobenzaldehyde to vials D1, D2, and D3, the vials were capped and vortexed for approximately 10 seconds. This was repeated three times and the solution was found to be saturated.
10:39--After adding 2 small scoops of 2-chloro-5-nitrobenzaldehyde to vials M1, M2, and M3, the vials were capped and vortexed for approximately 10 seconds. The solution was found to be saturated.
10:43--After adding 2 small scoops of 2-chloro-5-nitrobenzaldehyde to vials O1, O2, and O3, the vials were capped and vortexed for approximately 10 seconds. This was repeated two times and the solution was found to be saturated.
10:47--After adding 3 small scoops of 2-chloro-5-nitrobenzaldehyde to vials T1, T2, and T3, the vials were capped and vortexed for approximately 10 seconds. This was repeated three times and the solution was found to be saturated.
10:51--After adding 2 small scoops of 2-chloro-5-nitrobenzaldehyde to vials A1, A2, and A3, the vials were capped and vortexed for approximately 10 seconds. This was repeated once and the solution was found to be saturated.
10:54--After adding 1 small scoop of 2-chloro-5-nitrobenzaldehyde to vials E1, E2, and E3, the vials were capped and vortexed for approximately 10 seconds. This was repeated twice and the solution was found to be saturated.
11:58--All vials E1, E2, E3, A1, A2, A3, O1, O2, O3, T1, T2, T3, D1, D2, D3, M1, M2, and M3 were set in a large beaker filled one-quarter with water and placed in the sonicator. The temperature was read at 23.0C and the timer was set to 30 minutes.
11:41--All vials were removed from the sonicator and set out to cool to room temperature. Vials M1, M2, and M3 lost their caps during sonication and the methanol evaporated, thus these vials were remade from scratch with 300uL of methanol and enough 2-chloro-5-nitrobenzaldehyde such that the solution was saturated
11:44--Vials M1, M2, and M3 were set in a small beaker filled one-third with water and placed in the sonicator. The temperature was read at 25.0C and the times was set to 30 minutes.
11:45--Vials A1, A2, A3 were seeded with a few crystals of 2-chloro-5-nitrobenzaldehyde to induce crystallization.
11:50--Vials M1, M2, and M3 again lost their caps during sonication; they were immediately replaced and watched for the duration of sonication to ensure it did not happen again.
12:17--Vials M1, M2, and M3 were removed from the sonicator and set out to cool to room temperature.

03-06-2009
10:47--The saturated solutions from vials O1, O2, D3, E1, E3, and M3 were collected by pasteur pipette as the supernatant was cleanly separated from the remaining precipitate in the vials.
10:58--The supernatants from vials A1, A2, A3, T1, T2, T3, O3, D1, D2, and E2 were collected by filtration. The solutions were passed through a pasteur pipette filled with cotton, thus allowing only the supernatant to pass through and trapping any remaining solid. Vials M1 and M2 yielded no supernatant--presumably this was lost during/because of the sonication problem.
11:21--NMR tubes were prepared for all vials; the supernatants collected from each vial were placed in an appropriately labelled NMR tube and mixed with 500uL of CDCl3.

04-06-2009
9:30--The NMRs of all vials were taken on the 300MHz Varian instrument

References

[1] Solubility of 2-chloro-5-nitrobenzaldehye in THF
[2] Solubility of 2-chloro-5-nitrobenzaldehyde in acetonitrile
[3] Solubility of 2-chloro-5-nitrobenzaldehyde in toluene
[4] Solubility of 2-chloro-5-nitrobenzaldehyde in ethanol
[5] Solubility of 2-chloro-5-nitrobenzaldehyde in methanol
[6] Solubility of 2-chloro-5-nitrobenzaldehyde in non-aqueous solvents

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