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16th August 2012 @ 03:38
Sc: 1-10
Synthesis of SC2-1 from tryptamine and 4-nitrobenzaldehyde.

SC2-1 was successfully synthesised (1.4782 g, 5.040 mmol, 80.4%, m.p. 161-2 degrees).

HIRAC


SC1-1 and SC2-1 HIRAC.pdf


Procedure followed:

The basic procedure was identical to that used for SC1-1.

SC2-1%20reaction%20scheme.png

16th August 2012
Tryptamine (1.0039 g, 6.27 mmol) and 4-nitrobenzaldehyde (0.9905 g, 6.55mmol) were combined in dichloromethane (0.2 M, 33 mL). The reaction was stirred at room temperature (23 degrees) for 21 hours.

17th August 2012
Fine yellow crystals were visible in the reaction mixture. Crude product was obtained using vacuum filtration (wet yield of 1.5481 g). Further moisture was removed by drying under vacuum over the weekend. In addition, solvent was evaporated from the yellow filtrate to improve yield.

Recrystallisation experiments were performed on SC2-1 obtained from the filtrate fraction. SC2-1 (~50 mg) was heated in the presence of various solvents (~2 mL). Samples were left to recrystallise over the weekend. Solubility and crystal formation data were recorded:

Dichloromethane: compound dissolved, no immediate crystal formation. Gel-like recrystallisation observed within 3 hours.
Ethanol: compound dissolved, small crystals immediately formed.
Methanol: incomplete dissolution but immediate crystal growth was observed.
Toluene: compound dissolved, no immediate crystal formation. Small orange crystals formed over the weekend - different to the yellow coloured compounds seen in all other solvent recrystallisations. The identity of this product will be investigated using NMR.
1-propanol: compound dissolved, small crystals immediately formed.
Ethyl acetate: compound dissolved, no immediate crystal formation.
Ether: no dissolution observed.

Recrystallisation experiments for SC2-1.JPG
Recrystallisation experiments_1.JPG
Recrystallisation experiments_2.JPG


Photographs of crystals formed with chosen solvents.

20th August 2012
Dry yields of each recrystallisation were determined, as follows:

DCM: 41.6%
Ethanol: 83.4%
Methanol: 78.0%
Toluene: 68.2%
1-propanol: 78.0%
Ethyl acetate: 66.5%
Ether: not crystals.

Based on crystal appearance and yield, EtOH was found to be the optimal solvent.

Total yield for SC2-1: 1.4782 g, 5.040 mmol, 80.4%, m.p. 161-2 degrees.

22nd August 2012
As with SC1-1, NMR analysis was performed on SC2-1 to infer the formation of imine. Four independent NMR analyses were done on various samples of SC2-1. We did this to check for any chemical differences between the crude solid, solid obtained from the filtrate portion (see procedural information), and solids recrystallised from ethanol (fine yellow needles) and toluene (small orange crystals, unlike those formed using any other solvent, which was unexpected). There were no noticeable differences in the NMR spectra, indicating that despite slight differences in physical appearance, the compound present was the same in each case.
22.08.12_SC2-1_EtOH_1H.pdf


Attached Files
SC1-1 reaction scheme.png
SC2-1 reaction scheme.png
22.08.12_SC2-1_EtOH_1H.pdf
SC2-1_EtOH.zip
Recrystallisation experiments for SC2-1.JPG
Recrystallisation experiments_1.JPG
Recrystallisation experiments_2.JPG