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10th March 2012 @ 01:21
START: 12/03/12
FINISH: 13/03/12

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Summary and Conclusion
The reaction proceeded as expected with an isolated product yield of 81%. Proton NMR of the product showed trace amounts of solvent and the phenethylamine starting material. Failed recrystallisation attempt from diethyl ether and hexane. Product deemed adequate for use in further reactions.
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Background
See synaptic leap post: here.

Scheme KAB18-1



Hazard and Risk Assessment
Hazard and Risk Assessment KAB18-1


Following Experiments
Synthesis of N-[2-(3,4-Dimethoxyphenyl)ethyl]-1-phenylmethanimine (KAB19-1)
AgOTf catalysed synthesis of 1-phenyl-1,2,3,4-tetrahydroisoquinoline (KAB20-1)
Synthesis of 1-phenyl-1,2,3,4-tetrahydroisoquinoline (KAB20-2)
Synthesis of 1-phenyl-1,2,3,4-tetrahydroisoquinoline (KAB20-3)

Chemical Information
2-Phenethylamine (1) - SMILES: c1ccc(cc1)CCN, InChI: InChI=1S/C8H11N/c9-7-6-8-4-2-1-3-5-8/h1-5H,6-7,9H2, InChIKey: BHHGXPLMPWCGHP-UHFFFAOYSA-N.
Benzaldehyde (2)- SMILES: c1ccc(cc1)C=O, InChI: InChI=1S/C7H6O/c8-6-7-4-2-1-3-5-7/h1-6H, InChIKey: HUMNYLRZRPPJDN-UHFFFAOYSA-N.
N-Benzylidene-N-phenethylamine (3, KAB18-1) - SMILES: N(=C/c1ccccc1)\CCc2ccccc2, InChI: InChI=1S/C15H15N/c1-3-7-14(8-4-1)11-12-16-13-15-9-5-2-6-10-15/h1-10,13H,11-12H2/b16-13+, InChIKey: OOBAKFDIGIHHOM-DTQAZKPQSA-N

Procedure
Benzaldehyde (1.6 mL, 16 mmol, 1 eq) was added slowly to a stirring mixture of diethyl ether (4 mL) and 2-phenethylamine (2 mL, 16 mmol, 1 eq). The reaction was left to stir at rt from 08:36.
After 4 hours of stirring, the reaction mixture was dried over magnesium sulfate, filtered then concentrated to give a yellow liquid, which crystallised on standing (2.7 g, 81%). Confirmed by H-NMR.
KAB18-1
Raw H-NMR KAB18-1


Attempted recrystallisation from Et2O/hexane. Starting mass: 736 mg.

13/03/12 - Recrystallisation failed. No further purification attempts.

Summary and Conclusion
The reaction proceeded as expected with an isolated product yield of 81%. Proton NMR of the product showed trace amounts of solvent and the phenethylamine starting material. Failed recrystallisation attempt from diethyl ether and hexane. Product deemed adequate for use in further reactions.

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NOTES 12/03/12
- Flask: 19.4842 g
- UPLOAD NMR
- Still working out a way to assay the rxn progress. Two possibilities so far: Product has same Rf as benzaldehyde or has an Rf smaller than phenethylamine. Last attempt was in MeOH/EtOAc, 1:5, v/v. Phenethylamine moved, but suspected product spot was still on the base line. Doesn't make sense. Will attempt DCM/MeOH mixture.
- Sample may also contain some benzaldehyde.

NOTES 13/03/12
- ReXST failed. Wary of heating solution during reXST - product may hydrolyse to starting materials.
- Trace starting materials in product weren't removed, again because hydrolysis of the imine might occur.
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Linked Posts
Attached Files
Scheme KAB18-1
Hazard and Risk Assessment KAB18-1
Scheme KAB18-1
Table KAB18-1
Reaction mixture (4 h)
Raw H-NMR KAB18-1
KAB18-1
Comments
Re: Synthesis of N-benzylidene-N-phenethylamine (KAB18-1) by Matthew Todd
10th March 2012 @ 11:03
What's the procedure you're following? Don't you need a dehydrator?
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Re: Synthesis of N-benzylidene-N-phenethylamine (KAB18-1) by Paul Ylioja
11th March 2012 @ 22:14
I've used benzylamine and benzaldehyde to form the imine without the need for any drying agents during the reaction in near quant. yield. I was able to just dry the solution with MgSO4 before addition of lithium acetylides to the resulting imines without much hassle.
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