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Solubility book (3rd Edn)
To test the solubility of trans-cinnamic acid in benzene, toluene and acetonitrile by the SAMS NMR method.
Cinnamic acid had a solubility of 0.236M
[I corrected the value here and in the SAMS Spreadsheet - acetonitrile had three hydrogens AL]
in Acetonitrile, 0.252M in Benzene, and 0.257M in Toluene.
[There is a major error in the calculation in acetonitrile - check the sheet carefully JCB][Is the acetonitrile value in SolSum incorrect? Compare to the predicted value. AL]
The value for Benzene is much larger than the previous value for this combination. A 0.252M solution is the same as 37.3g/L, while the previous literature value for this was 13g/L. This helps prove that the values used to predict cinnamic acid in benzene are off, and need to be corrected.
12:35 Room Temperature 22.5C
12:40 Added about 1 mL of Benzene to 1 dram screw cap vial 1
12:42 Added about 1 mL of Toluene to screw cap vial 2
12:44 Added about 1 mL Acetonitrile to screw vial 3
12:46 Added about 1 mL of Trifluoroethanol to screw vial 4
13:00 Added 164mg of TCA to vial 1
[Do you have a little calculation sheet for planning amount to add? JCB]
13:02 Added 115mg of TCA to vial 2
13:04 Added 113mg of TCA to vial 3
13:06 Added 149mg of TCA to vial 4
13:10 Parafilmed all four vials
13:12 Filled a 600mL beaker with 47C tap water and placed all 4 vials in it
13:20 Placed all 4 vials in the beaker 48.5C
13:27 Removed from beaker at 44C
13:28 decanted solutions- used a pipette to decant trifluoroethanol because it was more dense than TCA.
11:45 Placed all 4 vials in a beaker filled with 27C tap water. Precipitate could been seen in all four samples. The precipitate was on the bottom of the vial for benzene, toluene, and acetonitrile, but floating on top of the trifluoroethanol. It does not look like any of the solvent had evaporated.
12:00 beaker at 25C, removed vials and prepared NMR samples.
[How exactly did you do this? You should drop the supernatant directly in a vial with CDCl3 - otherwise it can be very easy for solvent to evaporate and give erroneously much higher concentrations. JCB]
12:15 Took NMR spectra of all except Trifluoroethanol, because sample floated on top of solvent, and could not get only liquid into the tube. Also, ran out of Duterated Chloroform.
[In the future you can filter with cotton in a Pasteur pipette - you only need one or two drops for SAMS method JCB]
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