Researcher

David Bulger

Objective

To verify the solubility of 4-pyrenebutanoic acid in THF.

Procedure

A 0.75 M solution of 4-pyrenebutanoic acid in THF was made by adding 0.75 moles of 4-pyrenebutanoic acid to 1-mL volumetric flask and filling with THF to the 1-mL mark. The solution was then sonicated to dissolve the 4-pyrenebutanoic acid. However, some of the pyrenebutanoic acid did not dissolve. Therefore solubility of supernatant saturated solution was determined. Semi-Automated Measurement of Solubility (SAMS) was performed in order to verify the solubility of pyrenebutanoic acid.

A 0.60 M solution of 4-pyrenebutanoic acid in THF was made by adding 0.60 moles of 4-pyrenebutanoic acid to 1-mL volumetric flask and filling with THF to the 1-mL mark. The solution was then sonicated to dissolve the 4-pyrenebutanoic acid. However, some of the 4-pyrenebutanoic acid did not dissolve. Therefore solubility of supernatant saturated solution was determined. Two methods were used, Semi-Automated Measurement of Solubility (SAMS) and internal standard of 1,2-dichloroethane, in order to verify the solubility of 4-pyrenebutanoic acid.

Results

NMR

ONSCExp091-1A-HNMR
Raw JCAMP-DX File for ONSCExp091-1A-HNMR
ONSCEXP091
Raw JCAMP-DX File for ONSCEXP091

Pictures

exp091-1A_photo1a
exp091-1A_photo1b
exp091-1A_photo2
exp091-1A_photo3
Note: The following pictures are compressed. Higher resolution photos are available if needed.
Exp091-2A_photo4a
Exp091-2A_photo4b
Exp091-2A_photo5a
Exp091-2A_photo5b
Exp091-2A_photo6a
Exp091-2A_photo6b
Exp091-2A_photo7a
Exp091-2A_photo7b
Exp091-2A_photo7c
Exp091-2A_photo8a
Exp091-2A_photo8b
Exp091-2A_photo8c

Spreadsheets

ONSCExp091-01
ONSCExp091-02


NMR
Molarity of solution if solid had completely dissolved (M)
Solubility (M)
ONSCExp091-1A-HNMR
0.75
0.55, 0.64, 0.68
ONSCEXP091
0.60
0.76, 0.81, 1.03

Discussion

In Exp061, the solubility for 4-pyrenebutanoic acid in THF was calculated to be 1.39 M and 1.35 M for the methylene protons by SAMS, 1.15 M for the aromatic protons by SAMS, and 0.67 M for the aromatic protons using an internal standard. And in Exp084, the solubility was calculated to be 0.86 M using the acid proton, 0.92 M using the aromatic protons, and 1.03 M and 1.03 M using the methylene protons by SAMS and 0.55 M using an internal standard.

Experiment
NMR Signal Used
Method of Solubility Analysis
Solubility (M)
Exp061
Methylene
SAMS
1.39
Exp061
Methylene
SAMS
1.35
Exp061
Aromatic
SAMS
1.15
Exp061
Aromatic
Internal Standard
0.67
Exp084
Carboxylic acid
SAMS
0.86
Exp084
Aromatic
SAMS
0.92
Exp084
Methylene
SAMS
1.03
Exp084
Methylene
SAMS
1.03
Exp084
Methylene
Internal Standard
0.55
Exp091
Carboxylic acid
SAMS
0.55
Exp091
Aromatic
SAMS
0.64
Exp091
Methylene
SAMS
0.68
Exp091
Carboxylic acid
SAMS
0.81
Exp091
Aromatic
SAMS
1.03
Exp091
Methylene
SAMS
0.76
Exp091
Carboxylic acid
Internal Standard
0.32
Exp091
Aromatic
Internal Standard
0.35
Exp091
Methylene
Internal Standard
0.47
[Nice way to summarize the results to date JCB]

The attempt to make a 0.75 M solution of 4-pyrenebutanoic acid in THF was unsuccessful as some solid precipitated out of solution. The remaining solution was assumed to be saturated, and could therefore be used to determine solubility using SAMS. The solubility was measured to be 0.68 M using the methylene protons, 0.55 M using the carboxylic acid proton, and 0.64 M using the aromatic protons.

The attempt to make a 0.60 M solution was successful at a temperature of 36 degrees Celsius. However, when the temperature decreased to room temperature (19 degrees Celsius), solid precipitated out of solution indicating that this concentration also was not acheived. So SAMS was used again to determine the solubility of the remaining saturated solution, and the solubility was measured to be 0.76 M using the methylene protons, 0.81 M using the carboxylic acid proton, and 1.03 M using the aromatic protons, all of which are greater than the attempted concentration. The source of this error could be evaporation of the solvent during transfer to the NMR tube and/or simply the SAMS method. Either way, the solubility of 4-pyrenebutanoic acid in THF is estimated to be 0.55 - 0.60 M.

Note: While the internal standard calculations could be made by subtracting the predicted areas of the overlapping peaks, the margin for error is very large. Therefore, the internal standard measurements can be disregarded.

Conclusion

The solubility of 4-pyrenebutanoic acid in THF is estimated to be somewhere in between 0.55 M and 0.60 M.

Log

2009-05-18

15:03 Weighed 4-pyrenebutanoic acid (216.3 mg)
15:10 Inserted into 1-mL volumetric
15:21 Added THF up to 1-mL mark
15:27 Labeled (0.75 M DAB)
15:28 Parafilmed and added copper wire support
15:30 Photo (exp091-1A_photo1a)
15:31 Photo (exp091-1A_photo1b)
15:32 Sonicated (24 degrees Celsius)
15:59 (38 degrees Celsius)
16:14 Sonication ended
17:14 Removed from sonicator (27 degrees Celsius)
17:16 Added THF up to 1-mL mark [How much did you add roughly? JCB] Just a few drops.
17:20 Parafilmed and added copper wire support
17:22 Photo (exp091-1A_photo2)
17:22 Sonicated (26 degrees Celsius)
17:26 Removed from sonicator [Why only 4 min? JCB] I was going to sonicate it longer to let it dissolve, but decided to run NMR.
17:27 Transferred supernatant to vial and labeled (91-1A)
17:30 Photo (exp091-1A_photo3)
17:32 Centrifuged vial for 2 min
17:36 Added DMSO (700 uL) to NMR tube
17:37 Centrifuged vial for less than 1 min
17:38 Added supernatant from vial (100 uL) to NMR tube
17:44 Obtained NMR spectrum (Gain = 10) on 500 MHz spectrometer [Name the spectrum JCB] (ONSCExp091-1A-HNMR) Note: There are still some spinning side bands.
18:09 Parafilmed volumetric flask and vial

2009-05-19

14:25 Weighed 1-mL volumetric flask (15.587 7 g)
14:27 Added 4-pyrenebutanoic acid into volumetric flask
14:43 Weighed flask with acid (15.760 5 g)
14:44 Added THF up to 1-mL mark
14:50 Labeled volumetric flask (91-2A)
14:52 Photos (Exp091-2A_photo4a, Exp091-2A_photo4b)
14:55 Cleaned off label and weighed volumetric flask (16.513 8 g)
14:56 Relabeled, parafilmed, and added copper wire support
14:57 Sonicator temperature at 27 degrees Celsius
14:58 Began sonication
15:02 Vortexed for 10 sec
15:02 Sonicated
15:27 Reparafilmed (old parafilm melted)
15:28 Removed from sonicator
15:37 Sonicator temperature at 36 degrees Celsius
15:38 Photos (Exp091-2A_photo5a, Exp091-2A_photo5b) - solute completely dissolved
16:45 Photos (Exp091-2A_photo6a, Exp091-2A_photo6b)
16:51 Labeled NMR prep half-dram vial (91-NA)
18:05 Photos (Exp091-2A_photo7a, Exp091-2A_photo7b, Exp091-2A_photo7c) - solvent evaporated slightly, temperature decreased to room temperature (19 degrees Celsius), and some solid precipitated
18:06 Added THF up to 1-mL mark
18:10 Parafilmed
18:12 Vortexed for 1 min
18:15 Photos (Exp091-2A_photo8a, Exp091-2A_photo8b, Exp091-2A_photo8c) - did not go back into solution at room temperature
18:45 Added 700 uL CDCl3 to 91-NA
18:48 Pipeted saturated solution from volumetric flask into another half-dram vial
18:49 Added 100 uL saturated solution from half-dram vial to 91-NA
18:51 Added 10 uL 1,2-dichloroethane to 91-NA
18:52 Vortexed for 30 sec - did not go into solution (need to use DMSO-d6 instead of CDCl3)
19:05 Added 700 uL of DMSO-d6, 100 uL of saturated solution, 10 uL of 1,2-dichloroethane to another half-dram vial
19:14 Vortexed for 30 sec
19:19 Transferred to NMR tube (91) using Pasteur pipet
21:00 Parafilmed NMR tube

2009-05-20

12:05 NMR of ONSCEXP091

References


Solubility of 4-Pyrenebutanoic Acid in Organic Solvents
Solubility of 4-Pyrenebutanoic Acid in THF (solubility data viewer)

Acknowledgements

The author wishes to thank Dr. Jean-Claude Bradley for the use of his lab and Khalid Mirza for his help with the NMR.