TLC when making b-styrene’s?

Rabidreject

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Hey guys,

I just read the TLC of drugs post on here.
I am currently messing about with the Henry reaction but I have also been messing about with cold reductive animations of tryptamine - basically flying blind…

I am a little confused - I was just messing around with what chatGPT suggested as a starting point.
I’m a little confused. Do I need both UV wavelengths to see everything if I am not developing using iodine and simply viewing under UV?

My latest test used 8:2 ethyl acetate:ethanol - I have no ammonia and it said I could get away without it.

The thing I am finding is that both spots just rise to the top of where the mobile phase gets to…I’m not seeing any difference in the distance travelled, however I’m assuming - since I used 2,5-DMOBA and tryptamine just to practice with.
ACTUALLY - after the time it took me to write this post, I re-examined the plate under UV and can now see the starting point…

1. I will mostly be using this technique to ensure full conversion in syntheses as opposed to testing pre-bought drugs for purity - so I am assuming, if I spot with the RM and it shows multiple ‘dots’ after development, it shows there hasn’t yet been full conversion?

2. Is it also a good idea to take a sample of the un-refluxed mixture as well for comparison - assuming so as you need to see it develops differently?

I guess I’m a bit confused…

Here is my 2nd attempt - 2,5-DMOBA on the left and tryptamine on the right. (I get that you are unlikely to test these two next to each other) still though - tests

Also, I found it kinda funny when you said cut the plate with scissors as mine are glass lol
I did, however buy a glass cutter which works great but is hard to cut straight hence the slight wobbly edges.

MIEkxurSzn


Oh that’s strange, it turned the image sideways….okay bottom of the plate on the right, top on the left. Sorry about that.
So there are 2, 2,5-DMOBA spots and 3x tryptamine ones…not sure why the top spots of the tryptamine spots doesn’t show though…lack of ammonia?
 

Rabidreject

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Honestly, I thought the ‘spotting’ part would be the hard bit - how wrong I was! Ha
 

gnbarsh3463_11

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You have to choose the right eluent for your molecule. In case of tryptamine, 10:1 THF:Methanol seems to work fine, if you don't have THF then use EtOAc:Methanol or Hexanes:Methanol and try different fractions. NH3 in the eluent must be added for tryptamines, because the plates are acidic and can interact with amines. You can wash the plates and reuse them.
 
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