Objective

To measure the solubility of the Ugi product (206B) in different solvents by NMR.

Procedure

Saturated solutions of ugi product 206B was prepared in seventeen solvents in one dram vials, after vortexing excess solute in each for 10min. The solutions were left to equilibrate over-night. 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. The relative integrations of a solute peak and the internal standard peak were compared to estimate the concentration of the solute in each supernatant.

Results



Solvent
Internal standard
HNMR
Solubility (M)
THF
Acetone
HNMR
0.25
benzene
Acetonitrile
HNMR
0.01
methanol
Acetonitrile
HNMR
0.05
ethanol
Acetonitrile
HNMR
0.02
toluene
Acetonitrile
HNMR
0.01
acetonitrile
Acetone
HNMR
0.02
chloroform
Acetonitrile
HNMR
0.57
DMSO
Acetonitrile
HNMR
0.23
diethylether
Acetonitrile
HNMR
0.00
cyclohexane
Acetonitrile
HNMR
0
cyclopentane
Acetonitrile
HNMR
0
dichloromethane
Acetonitrile
HNMR
0.24
carbontetrachloride
Acetonitrile
HNMR
0.00
isopropanol
Acetonitrile
HNMR
0
N,N-dimethylformamide
Acetonitrile
HNMR
0.24
water
Acetone
HNMR
0.00
n-hexane
Acetonitrile
HNMR
0
Spreadsheet

Discussion

The Ugi product (206B) is most soluble in Chloroform (0.57M). THF, DMSO, DCM and DMF dissolved the Ugi product to almost same extent (range 0.23- 0.25) . Toluene, benzene, carbontet, acetonitrile, ethanol and methanol do not dissovle the Ugi product as well, the extent of its solubility in these solvents range from 0.00- 0.05M. Surprisingly methanol is some what a better solvent than ethanol, It is almost insoluble in water.
Cyclohexane, cyclopentane and n-hexane HNMR peaks proved to be coinidental with the t-butyl peaks, the remaining peaks corresponding to the Ugi product were almost absent or insignificant in those solvents, prompting a zero solubility call.
The Ugi product is presumed to be less denser than water, DCM, chloroform and carbontet because it floats on these solvents.

Conclusion

Solubility of the Ugi product (206B) has been successfully determined in different solvents. In general the above solvents can be divided in three groups based on the solubility of the Ugi product
Solvent
Solubility (M)

chloroform
0.57
THF, DMSO, DCM and DMF
0.23-0.25
Toluene, benzene, cyclohexane,
cyclopentane, n-hexane, carbontet,
acetonitrile, water, diethylether,
isopropanol,ethanol and methanol
0.00-0.05


Log

2009-02-07

13:00 Prepared satured solutions of the Ugi product (206B) in different solvents listed below. Saturation was achieved by vortexing the solution for 10min after last addition of the solute.
Vial number
Solvent
Internal standard
(added to the NMR tube)
Int.Std (Peak);
Solvent (Peaks) in CDCl3 (ppm)
1
THF
Acetone
2.16; 3.72 &1.84
2
benzene
Acetonitrile
2.00; 7.33
3
methanol
Acetonitrile
2.00; 3.66 & 3.43
4
ethanol
Acetonitrile
2.00; 3.68, 2.61 & 1.22
5
toluene
Acetonitrile
2.00; 7.00-7.38 & 2.34
6
acetonitrile
Acetone
2.16; 2.00
7
chloroform
Acetonitrile
2.00; 7.25
8
DMSO
Acetonitrile
2.00; 2.62
9
diethylether
Acetonitrile
2.00; 3.47 & 1.20
10
cyclohexane
Acetonitrile
2.00; 1.43
11
cyclopentane
Acetonitrile
2.00; 1.50
12
dichloromethane
Acetonitrile
2.00; 5.29
13
carbontetrachloride
Acetonitrile
2.00; none
14
isopropanol
Acetonitrile
2.00; 4.00, 2.16 & 1.20
15
N,N-dimethylformamide
Acetonitrile
2.00; 8.01, 2.97 & 2.88
16
water
Acetone
2.00; 1.58
17
n-hexane
Acetonitrile
2.00; 1.29, 1.27 & 0.89

2009-02-08

20:30 The sample were centrifuged, took pics ; picture1; picture2
2:55 The supernatants were decanted into new vials. They were left overnight pending NMR analysis.

2009-02-10

20:00 Obtained HNMR of samples by dissolving 100uL of the saturated solution in a CDCl3 (700uL) except for the water solution for which D2O was used.
To all NMR tubes acetonitrile (10uL) was added as an internal standard, except for tubes containing toluene, water and acetonitrile itself, where acetone (10uL) was used as an internal standard.