Objective

To determine the solubility of phenanthrene-9-carboxaldehyde and 1-pyrenebutyric acid in methanol by UV-Vis spectroscopy

Procedure

Saturated solutions of phenanthrene-9-carboxaldehyde and 1-pyrenebutyric acid in methanol were prepared in half dram vials and left to equilibrate for 3 hours. The supernatant from each solution was subjected to dilutions until UV absorbance for them fell under 1.0 absorbance units. Molar absortivity ε values for the compounds were obtained by recordring the UV spectra of there solutions of known concentrations.

Results

Saturated solutions
024A-2
024A-3
024B-2
024B-3
024ACal-1
024ACal-2
024BCal-1
024BCal-2
Spreadsheet

Discussion


Table 1
Sample
Concentration (mM)
in Methanol

Wavelength
(nm)

ε cm-1M-1
Phenanthrene-9-carboxaldehyde
0.01387
250
42935.62

0.01387
316
9382.316
1-Pyrenebutyric acid
0.02375
242
65728.91

0.02375
275
45828.41

0.02375
341
38459.7
As described in Table 1, the molar extinction coefficient of phenanthrene-9-carboxaldehyde in methanol at 250nm was found to be 42935 and at 316nm it was 9382.
For 1-Pyrenebutyric acid the molar extinction coefficient at 242 nm was 65728, at 275nm it was 45828 and at 341nm it was determined to be 38459 cm-1M-1
The following are the concentrations calculated for the solutions (numbers in blue correspond to phenanthrene-9-carboxaldehyde and the ones in green to 1-pyrenebutyric acid.
Table 2
Solution
Concentration (mM)
ONSC024A-1---
77.72
ONSC024B-1---
22.7

Conclusion

Concentration of a saturated solution of Phenanthrene-9-carboxaldehyde in methanol has been determined to be 0.078M
Concentration of a saturated solution of 1-Pyrenebutyric acid in methanol has been determined to be 0.022M

Log

2009-01-13

14:00 Made-up saturated solutions of phenanthrene-9-carboxaldehyde and 1-pyrenebutyric acid in methanol in half dram vials. The vials were vortexed for 8 min each inorder to ensure saturation. The vials were left undisturbed for three hours to equlibrate.
14:20 Temperature in the lab was recorded to be 24C
17:10 Obtained a picture of the saturated solutions after equlibration.
17:45 Dilutions of the saturated solutions were performed as below
Solution ID
Description
024A-1
Saturated solution of Phenanthrene-9-carboxaldehyde
024A-2
100uL 024A-1 in methanol made-up in a 10mL Volumetric flask
024A-3
100uL 024A-2 in methanol made-up in a 10mL Volumetric flask
024B-1
Saturated solution of 1-Pyrenebutyric acid
024B-2
100uL 024B-1 in methanol made-up in a 10mL Volumetric flask
024B-3
100uL 024B-2 in methanol made-up in a 10mL Volumetric flask

18:00 Obtained UV spectra of the dilute solutions.
19:30 Weighed 19.6mg phenanthrene-9-carboxaldehyde and dissolved it in methanol, the solution was made-up to the mark in a 100mL Volumetric flask. This solution is 024ACal-1
20:00 Solution 024ACal-2 was made by dissolving 024ACal-1 (250uL) in methanol in a 10mL volumetric flask.
20:30 Weighed 16.0 mg 1-pyrenebutyric acid and dissolved it in methanol, the solution was made-up to the mark in a 100mL volumetric flask. This solution is 024BCal-1
20:50 Solution 024BCal-2 was made by dissolving 024ACal-1 (250uL) in methanol in a 10mL volumetric flask.
21:40 Obtained UV spectra of the above solutions.