Researcher

Valentine Anyiam

Objective

Determination of the solubility of benzoic acid in a series of glycol solvents: ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and polyethylene glycol. This experiment will also use the SAMS technique with a 2-chamber NMR tube to avoid solubility problems between CDCl3 and ethylene glycol polymers.

Procedure

Obtain five separate test tubes and fill each one with about 600mg of benzoic acid. Then mix 2mL of ethylene glycol within the first test tube, 2mL of diethylene glycol within the second test tube, 2mL of triethylene glycol within the third test tube, 2mL of tetraethylene glycol within the fourth test tube and 2mL of polyethylene glycol within the fifth test tube. Place each of these samples within a bath of boiling water for about 30 minutes. After boiling, transfer the supernatant within each solution into another clean test tube and then place these test tubes within a room temperature water bath. Allow them to sit within the water baths for approximately 1 day. Check the next day for signs of precipitation.

Results

Solbuilities could not be obtained.

Discussion

None of the glycol solutions precipitated out even after sitting in the room temperature water bath for more than a week. Supersaturation may be possible but is very unlikely.

Conclusion

The benzoic acid solutions may be too super saturated in order to confirm with accuracy the solubilities via NMR analysis.

Log

2012-05-11

16:36- 613.7mg of benzoic acid was poured into a 20mL test tube labeled test tube EG.
16:38- 605.7mg of benzoic acid was poured into a 20mL test tube labeled test tube DEG.
16:40- 610.1mg of benzoic acid was poured into a 20mL test tube labeled test tube TEG.
16:42- 601.4mg of benzoic acid was poured into a 20mL test tube labeled test tube TetraEG.
16:44- 607.3mg of benzoic acid was poured into a 20mL test tube labeled test tube PEG.
16:48- A beaker was filled about halfway with water and then placed on top of a hot plate. The hot plate was then turned on and set to 10.
16:51- 2mL of ethylene glycol was mixed with the benzoic acid in test tube EG.
16:53- 2mL of diethylene glycol was mixed with the benzoic acid in test tube DEG.
16:55- 2mL of triethylene glycol was mixed with the benzoic acid in test tube TEG.
16:57- 2mL of tetraethylene glycol was mixed with the benzoic acid in test tube TetraEG.
16:59- 2mL of polyethylene glycol was mixed with the benzoic acid in test tube PEG.
17:04- The water on top of the hot plate was boiling. The hot plate was changed to a setting of 9. All five solutions were placed within the hot water bath.
17:41- Another beaker was filled with warm water so it could be used as a room temperature water bath. The temperature of this water bath is 27C.
17:43- The hot plate was turned off.
17:45- The supernatant within test tube EG was pipetted out and transfered into another small test tube labeled test tube EG-Sup. This test tube was then placed within the room temperature water bath.
17:50- The supernatant within test tube DEG was pipetted out and transfered into another small test tube labeled test tube DEG-Sup. This test tube was then placed within the room temperature water bath.
17:53- The supernatant within test tube TEG was pipetted out and transfered into another small test tube labeled test tube TEG-Sup. This test tube was then placed within the room temperature water bath.
17:56- The supernatant within test tube TetraEG was pipetted out and transfered into another small test tube labeled test tube TetraEG-Sup. This test tube was then placed within the room temperature water bath.
17:59- The supernatant within test tube PEG was pipetted out and transfered into another small test tube labeled test tube PEG-Sup. This test tube was then placed within the room temperature water bath.
18:00- Room Temperature water bath at 24C.

2012-05-24

14:00- Room temperature water bath is at 21C. None of the solutions showed any signs of precipitation.