Objective

To measure the solubility of the 4-pyrenebutanoic acid in different solvents by NMR.

Procedure

Saturated solutions of 4-pyrenebutanoic acid was prepared in seventeen solvents in one dram vials, after vortexing excess solute in each for 10min. The solutions were left to equilibrate for three days. The solutions were then centrifuged and the supernatants were decanted in to separate vials. The supernatants (100uL) were dissolved in a deuterated solvent and an internal standard (10uL) in an NMR tube and a proton NMR was obtained. Although an internal standard had been added to the solutions, it was not used to determine the solubility, instead SAMS was used for that purpose.

Results



Solvent
Int. Std
HNMR
int. Std
HNMR
THF
DCM
HNMR
DCE
HNMR
benzene
DCM
HNMR
DCE
HNMR
methanol
DCM
HNMR
DCE
HNMR
ethanol
DCM
HNMR
DCE
HNMR
toluene
DCM
HNMR
DCE
HNMR
acetonitrile
DCM
HNMR
DCE
HNMR
chloroform
DCM
HNMR
DCE
HNMR
DMSO
DCM
HNMR
DCE
HNMR
diethylether
DCM
HNMR
DCE
HNMR
cyclohexane
DCM
HNMR
DCE
HNMR
cyclopentane
DCM
HNMR
DCE
HNMR
dichloromethane
CH3CN
HNMR
DCE
HNMR
carbontetrachloride
DCM
HNMR
DCE
HNMR
isopropanol
DCM
HNMR
DCE
HNMR
N,N-dimethylformamide
DCM
HNMR
DCE
HNMR
n-hexane
DCM
HNMR
DCE
HNMR
Spreadsheet
Spreadsheet-61B
Spreadsheet-61C (using XY JCAMP-DX files) - [only THF added -rest need to be filled in JCB]



Discussion

One of the methylene groups (~2.4 ppm) had been used to integrate the solute to determine its solubility in the solvents. Using aromatic protons did not yield expected results. This may be a result of the fact that the protons on sp2 take longer to relax and the delay time (d1=0.3s) between 900 pulses was insufficient.

Conclusion

Solubility of 4-pyrenebutanoic acid has been determined in different solvents.

Log

2009-02-15

19:00 Labeled sixteen one dram vials with sixteen solvents listed in the above results table.
19:20 To labeled vials respective solvents (~600uL) was added.
20:10 Three to four narrow spatula full 4-pyrenebutanoic acid was added to each vial, after the addition every vial was vortexed for about 30sec. Vials labeled THF, DCM, DMSO and DMF got clear hence another 3 spatula full acid was added to them and vortexed again for 30s. Now all the vials had some undissolved solid remaining in them.
20:50 At this time vials were vortexed for 10 min in groups of 8 tied with rubber band, so it became easier to vortex and also to reduced the over all vortexing time.
21:00 Vials with DMSO and DMF solutions further cleared-up, therefore another 2 spatula full acid was added to them and vortexed for yet another 10min.
21:15 After the vortexing was complete there was still some solid that remained undissolved in each vial. The solutions were then left to equlibrate over night.

2009-02-19

20:00 The vials containing the solutions were centrifuged (benchtop centrifuge) and the supernatants were collected in to separate vials. Solutions containing methylene chloride, chloroform and carbontet had solid acid floating over the supernatant (solvents with high specifc gravity), for these solutions the bottom clear liquid was carefully piipetted out into separate vials...inspite of all care to spearate the solid from the supernatans, some solid particle were still seen in the pipetted supernatants..therefore solubilties based on these solutions may contain some error. However, the solubilites in these high density solvents appeared to be very low. Therefore, for the purpose this experiment was conducted, the resultant solubilities may still be used if they are confirmed to be ver low. (We are looking for solvents which would make ~2M conc. solutions)

2009-02-20

15:00 To sixteen clean and dry NMR tubes deuterated solvent (700uL) was added (shown in the table below), followed by saturated supernatants (100uL) and an internal standard (10uL).
Supernatant
Deuterated solvent
Internal standard
THF
DMSO-d6
DCM
benzene
DMSO-d6
DCM
methanol
DMSO-d6
DCM
ethanol
DMSO-d6
DCM
toluene
DMSO-d6
DCM
acetonitrile
DMSO-d6
DCM
chloroform
CDCl3
DCM
DMSO
DMSO-d6
DCM
diethylether
DMSO-d6
DCM
cyclohexane
CDCl3
DCM
cyclopentane
CDCl3
DCM
dichloromethane
DMSO-d6
acetonitrile
carbontetrachloride
DMSO-d6
DCM
isopropanol
DMSO-d6
DCM
N,N-dimethylformamide
DMSO-d6
DCM
n-hexane
CDCl3
DCM
20:00 Obtained HNMRs of solutions on the 500MHz Varian Invoa instrument. The NMR tubes containing the samples were left capped in the hood.

2009-02-25

00:00 To NMR tubes containing the samples (in deuterated solvents, of which some may have evaporated) 1,2-dichlorethane (10uL) was added, the NMR solution in the tube was thoroughly mixed.

2009-02-26

05:00 HNMR of the samples were obtained, these spectra are labelled with DCE suffuix...there are series # 2 spectra.