Objective

To assess the solubility of 4-pyrenebutanoic acid in THF and a 3:1 mixture of THF and methanol by NMR.

Procedure


Results


NMR tube method
4-pyrenebutanoic acid in THF(ONSC74-N1)
4-pyrenebutanoic acid in 3:1 THF:MeOH(ONSC74-N2)
Vial method
4-pyrenebutanoic acid in THF(ONSC74-V1)
4-pyrenebutanoic acid in 3:1 THF:MeOH(ONSC74-V2)

Spreadsheet

Discussion

It is difficult to see any decent peaks in the NMRs run with out deuterated solvents and solid in them..therefore results are based on the values obtained from the runs of the supernatants with deuterated solvents. Since David had been obtaining decent HNMRs without deuterated solvent (Exp072; example 4-phenylbutyric acid), it is may be inferred that solid in NMR tubes causes intense peak distortions. However there may be some degree of tolerance to the amount of solid in the tube before peak distortion occurs...Therefore it may still be possible to perform an entire solubility estimation in an NMR tube without having to separate the solid from the supernatant, if the amount of solid under the supernatant is small.

[Report the solubility of 4-pyrenebutanoic acid in THF based on SAMS analysis of vial method JCB]

Log

2009-04-07

12:00 Made-up a 3:1 solution of THF /methanol (1mL) by mixing THF (750uL) and methanol (250uL) in a one dram vial.
12:30 Two spatula scoops of 4-pyrenebutanoic acid was added to 500uL of the 3:1 THF: MeOH solution.- The solution in the vials is labeled V1
12:35 To another one dram vial containing 300uL of THF, 4-pyrenebutanoic acid was added. The solution in the vials is labeled V2
12:45 To two NMR tubes labeled N1 and N2; 4-pyrenebutanoic acid was added. To the NMR tube 1, THF (200uL) THF was added and capped. To the NMR tube labeled 2, a 3:1 THF:MeOH (200uL) solution was added and capped.
12:50 Placed the one dram vials V1 and V2 and the NMR tubes N1 and N2 in to a sonicator, to dissolve the solid inorder to make a saturated solution.
13:10 Removed from the sonicator.
13:20 Started to run a HNMR of the samples with solid in it.
13:30 Unable to obtain a decent spectrum (severe peak distortions)...popped out the sample tube and pushed it about 1cm out of the spinner.it is assumed that by doing so the liquid in the sample tube remains be the focus of the NMR probe. Obtained a one scan spectrum (nt=1) with gain set to 10. These NMRs of the solutions in the NMR tubes along with solid settled at the bottom are labeled ONSC74-N1 and ONSC74-N2.
13:50 Decanted the supernatants from the vials V1 and V2 in to two clean vials. Transferred 100uL of each supernatant into two clean and dry NMR tubes, added 700uL CDCl3 and obtained HNMR.These NMRs are labeled ONSC74-V1 and ONSC74-V2.