Researcher

Evan Curtin

Objective

To synthesize benzalaniline at 2M in trifluoroethanol(1), n-hexane(2) and isopropanol (3)

Procedure

Benzaldehyde (50mmol, 5.306g) was reacted with aniline (50mmol, 4.656g) at 2M concentration in trifluoroethanol (20.351g) and isopropanol (12.150g). Precipitate from the isopropanol mixture was filtered using a buchner funnel, washed with ethanol and characterized by HNMR. The trifluoroethanol did not form a precipitate and the solution was analyzed by HNMR.

Results

UC-EXP271 Plan Sheet
Characterization of 3A:


Reaction Mixture for 1:


Discussion

1) Imine did form in trifluoroethanol, however there was not enough to form a precipitate. The solubility of benzalaniline in trifluoroethanol is 3.682, which explains why the product never precipitated.
2) Aniline is not soluble enough in n-hexane to be able to run the reaction at high concentrations.
3) The product precipitated in isopropanol and had a yield of 62%. The solubility for benzalaniline in isopropanol at 0C is 0.3M. Running the reaction at 2M would result in an optimal yield of 85%. Human error is likely to blame for the discrepancy.

Conclusion

Benzalaniline was successfully synthesized in isopropanol, however it is too soluble to precipitate out of trifluoroethanol and the starting materials are not soluble enough to dissolve in hexane.

Log

2011-08-01

15:08 - Weighed reactants. Weighed 50 mmol of each reactant as well as enough solvent to run the reaction at 2M trifluoroethanol (20.3527g), n-hexane (10.3841g), and isopropanol (12.1479g). Used roughly half of each solvent to dissolve the starting materials. However, Aniline did not mix with n-hexane, even after roughly quadrupling the volume with hexane.
15:09 - Mixed solutions of benzaldehyde and aniline from in a 250mL erlenmeyer flask with both trifluoroethanol and isopropanol as solvents. Added magnetic stirring rod, parafilmed and set on a stirring plate.
15:50 - Precipitate formed in 3, removed from stirring plate and put in an ice/water bath.
15:58 - Filtered 3, put solid in 2 separate vials, each with punctured caps, in a desiccator under high vacuum.
17:05 - 1 Still has no precipitate, left on stirring plate.
2011-08-02
16:42 - Re moved sample 3 from desiccator (now called 3A), weighed. Mass is 5.5828g.
17:02 - Added CDCl3 to a small amount of 3A, put in NMR tube.
17:14 - Took HNMR of sample 3A using 500MHz varian NMR.