UC-EXP263scheme.png

Researcher

Evan Curtin

Objective

To repeat the synthesis of benzalaniline from aniline and benzaldehyde at a 2M concentration in ethanol in order to obtain solubility data as explained on the imine project page.

Procedure

Weigh benzaldehyde and aniline in eqimolar amounts. Weigh enough ethanol so that the final mixture will be the desired concentration (calculations shown here). Mix benzaldehyde and ethanol into 50mL Erlenmeyer flask. Add aniline slowly, swirling. Stir on magnetic stirring plate for a few hours. Cool mixture, filter using a Büchner funnel. Dry the solid in a desiccator under high vacuum.

Results

Calculations Sheet UC-EXP263plan

Characterization of 1A (Benzalaniline after 3 days of high vacuum):

Appearance: Light yellow solid
Amount: 5.6250g (56.2% yield)
mp: 43-47°C
HNMR (solvent: CDCl3):



Characterization of 1B (Benzalaniline after 4 days of high vacuum):
Appearance: Light yellow solid
Amount: 5.5842g
mp: 45-47C
HNMR (solvent: CDCl3):






Discussion

  1. The 2.2 ppm singlet in the NMR of 1A is probably due to traces of acetone in the NMR tube. This peak is not present in the NMR of 1B.
  2. The melting point of 45 C for benzalaniline is somewhat below that reported in the literature - averaging at 52.7 C.
  3. The solubility of the benzalaniline in ethanol is reported to be 1.27 M at room temp and it explains the formation of 2 layers since the reaction was carried out at 4M. The low melting point of the product is consistent with observing 2 layers until the mixture was cooled to 0C, where solid precipitated out and could be filtered.

Conclusion

Benzalaniline was synthesized in 56.2% yield by reacting benzaldehyde and aniline at 4M concentration in ethanol and cooling to 0C to precipitate product.

Log

2011-04-15

11:18 - Weighed out the reactants: 5.1407g aniline, 5.8578g benzaldehyde and 2.5465g of ethanol (200 proof, anhydrous).
11:19 - Mixed reagents in a 50mL Erlenmeyer flask. The mixture heated up. Covered flask in parafilm
11:30 - Sonicated the mixure. A white cloud appeared.
11:32 - Set on magnetic stirring plate
13:23 - Observed mixture, it now has 2 layers. Cooled mixture in an ice/water bath. Some solid formed.
13:34 - Vacuum filtered the mixture using a Büchner funnel and house vacuum. The mixture went straight through the funnel, then formed solid in the filtration flask. Some solid was collected in the funnel.
13:51 - Vacuum filtered the mixture from the first filtration, using a few mL of cold (ice water bath) ethanol to collect some of the solid.
14:03 - Removed solid from the vacuum filter (from both the first and second filtrations), and put into a push cap vial (mass of vial with the cap is 14.1123g).
14:23 - Punctured the cap of the vial and put in dessicator under high vacuum.

2011-04-18

14:24 - Removed sample from desiccator (1A). Weighed. Mass of product is 5.6250g.
14:28 - Obtained melting point of sample. 43-47°C. Left sample in vial with cap on in a fume hood.

2011-04-28

11:31 - Made solution of benzalaniline and CDCl3.
11:45 - Took HNMR spectrum of solution (1A) using 500MHz varian NMR. Quick review revealed presence of an upfield peak uncharacteristic of benzalaniline.
12:05 - Put sample in desiccator under high vacuum.

2011-04-29

12:15 - Removed Sample from desiccator. Sample is now 1B
12:36 - Took some sample, added CDCl3, put in NMR tube
12:45 - Took HNMR using 300 MHz varian NMR.
12:50 - Took melting point and weighed 1B, mp is 45-47°C and mass is 5.5842g.