Researcher

Jenna Mancinelli

Objective

To generate a solubility-temperature curve for boc-glycine in THF.

Procedure

Label five vials, into which 0.5 g THF is pippetted. The appropriate amount of boc-glycine is added to each vial. Each vial is parafilmed tightly and vortexed for 15 seconds. All five vials are placed into heating-cooling thermostat with 60% water and propylene glycol bath set to 40C until all mixtures become unsaturated. Once all vials have reached solution, the temperature of the bath is lowered in 1 to 2 degree increments. The temperature at which precipitates occur is recorded.

Results

Spreadsheet


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Discussion

Based on the two data points obtained, a solubility-temperature curve was able to be to created. Using this graph, the concentration at room temperature, 23C, is predicted to be 4.4977 M. In comparison to previous experiments, these results are consistent, being neither lower than the lowest obtained values nor higher than the highest obtained values. Experiment 207 showed that the concentration of boc-glycine in THF is 3.45 M. As no temperature is listed in that experiment, it is possible that the temperature may have been lower than room temperature. No temperature is recorded for Experiment 071 either, which claims the solubility to be 4.77 M. It is possible that here the temperature was higher than room temperature, explaining the difference in concentrations amongst the various experiments. From the results obtained from this experiment, it is possible to predict the concentration of boc-glycine in THF at specific temperatures. Further experimentation would aid in filling in the gaps between and beyond data points. For instance, a 3.5 M solution would probably precipitate at about -8C. This can be tested along with that of other concentrations.

Conclusion

A solubility-temperature curve was obtained of boc-glycine in THF.

Further experimentation is necessary to find a more accurate curve.

Log

2009-08-03

16:00 Labeled five vials
16:10 Pippetted approximately 0.5 g THF to each vial. Exact amounts recorded in results.
16:30 Weighed out specific amounts of boc-glycine. Added each weighed sample to the appropriate vial. Exact amounts recorded in results.
17:15 Parafilmed each vial and labeled each with a tag. Each vial was vortexed for 15 seconds. Vials 1, 2, and 3 showed clear homogenous solutions, while vials 4 and 5 showed saturated solutions.
18:00 Placed all five vials in heating-cooling thermostat with 60% water and propylene glycol bath set to 40C.
18:10 Vial 5 observed to be saturated solution still. Left in bath.
18:20 Vial 5 reached solution. With all five vials in the bath, began lowering the temperature of the bath in two to three degree increments.
20:00 Vial 5 precipitates at 1C.
20:35 Vial 4 precipitates at -19C
20:45 Bath reached -25C. Vials 1, 2, and 3 never showed precipitate.