Objective

To determine the solubility of 4-acetamidobenzoic acid and nicotinic acid in methanol, ethanol, acetonitrile, THF and benzene

Procedure

Solutions of 4-acetamidobenzoic acid and nicotinic acid were prepared in methanol, ethanol, acetonitrile, THF and benzene, by dissolving excess of solute in them.These solutions were left in a water-glycol bath at 50C for 5h, then they were left for the next 19h at 25C. Proton HNMR spectra of the supernatant from each solution was obtained on a 500MHz Varian invo instrument. Solubility of the solute was determined using SAMS.

Results

SAMS Spreadsheet
HNMR
4-acetamidobenzoic acid
nicotinic acid

Conclusion

Solubility of 4-acetamidobenzoic acid and nicotinic acid has been determined in five solvents.

------------------------Solubility (M)---------------------------
Solvent
4-acetamidobenzoic acid
nicotinic acid
methanol
0.19
0.6
ethanol
0.23
0.09
acetonitrile
0.01
0.00
THF
0.17
0.09
benzene
0.00
0


Log

2009-08-24
16:00 Ten half dram vials were labeled 1-10
16:10 Placed two spatula tip full 4-acetamidobenzoic acid in first five vials labled 1-5.
16:35 Placed two spatula tip full nicotinic acid in the remaining five vials labeled 6-10.
16:40 Switched on the water-glycol bath and set it to 50C
16:55 Pipetted out 500uL solvents; methanol in vials 1 and 6, ethanol in 2 and 7, acetonitrile in 3 and 8, THF in 4 and 9 and benzene in 5 and 10.
17:20 The vials were then screw-capped tightly and parafilmed. Each vial was vortexed for about 30s after the solvent addition.
17:45 Placed the vials in the bath now at 50C.
21:35 Set the water-glycol bath to 25C
2009-08-25
16:45 Removed the vials from the water-glycol bath
17:10 Pipetted out 100uL of the supernatant from each vial in to 10 clean and dry NMR tube containing CDCl3 (600uL). When the supernatant from vial 4 was added to CDCl3 in the tube, the contents of the tube turned cloudy, indicating the precipitation of 4-acetamidobenzoic acid from chloroform-D. This is likely if the solubility of the acid is higher in the supernatant (THF solution) than in CDCl3. Therefore pipetted out another 100uL of the supernatant in to another clean-dry NMR tube containing DMSO-d6. This time the solution remained clear.
19:20 Obtained HNMR of all the solutions. The H-NMRs are labeled UCExp137-xA; x= the vial number.