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Topic: TLC stain  (Read 5548 times)

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Offline Urbanium

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TLC stain
« on: April 22, 2015, 09:44:40 AM »
Is anyone aware of a TLC dip which does not oxidise the "oxidisable" spots on the plate (KMnO4, Goofy etc.), but instead acts as a reducing agent?

Offline Dan

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Re: TLC stain
« Reply #1 on: April 22, 2015, 10:22:00 AM »
Goofy

I had to google that. Where does the name come from? I've always known it as CAM...

I found a recipe for 0.1% morin in MeOH (source). Presumably morin is an antioxidant, so the mechanism would be reductive... I've never used it.
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Offline Babcock_Hall

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Re: TLC stain
« Reply #2 on: April 22, 2015, 10:48:09 AM »
What compound or class of compounds are you trying to visualize?

Offline Urbanium

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Re: TLC stain
« Reply #3 on: April 22, 2015, 11:33:48 AM »
The compound has two alkyls and few of sulfurs and oxygens between, like an alternating ether-thioether system. For some reason I can't oxidise it, but since the whole compound is a dimer with an S-S bond in the middle, I was thinking of reductive cleavage on the TLC plate.

Offline Babcock_Hall

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Re: TLC stain
« Reply #4 on: April 22, 2015, 12:21:57 PM »
Once reduced, you can use a TLC spray based on Ellman's reagent.  Thioethers?  IIRC we once tried a method that we found referenced in a paper coauthored by Isaac Asimov.  I think it used azide, but I don't believe that we had great success with it.

Offline kriggy

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Re: TLC stain
« Reply #5 on: April 23, 2015, 11:03:06 AM »
The compound has two alkyls and few of sulfurs and oxygens between, like an alternating ether-thioether system. For some reason I can't oxidise it, but since the whole compound is a dimer with an S-S bond in the middle, I was thinking of reductive cleavage on the TLC plate.

Maybe hydrogen peroxide? we learned that thioethers can be easily oxidized to sulfoxides or sulfones

Offline Babcock_Hall

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Re: TLC stain
« Reply #6 on: April 23, 2015, 04:11:09 PM »
G. E. Howard and J. Baldry, Analyst 94 July 1969, pp. 589-593
These authors use chloramine T for thioethers and perhaps disulfides.  I don't recall having tried this myself.  The azide method I mentioned used iodine, and it came from Chargaff's lab in 1948.  We did not have much luck with it, but we did not try very hard.

Offline Babcock_Hall

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Re: TLC stain
« Reply #7 on: April 10, 2024, 01:15:47 PM »
Acta Chemica Scandinavica 1960 14:1980-1984.  Stig Akerfeldt used 1% CuCl2 in 50% ethanol containing 5% ammonia as a spray reagent to produce black spots for cysteamine S-phosphate on paper.  It also reacts with thiophosphate, but I am not sure how other compounds would behave.

Erratum
In regards to my previous message, I had a look at the 1969 paper by Howard and Baldry.  They did not use chloramine T for TLC detection; it was a reagent.
« Last Edit: April 10, 2024, 05:05:08 PM by Babcock_Hall »

Offline Babcock_Hall

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Re: TLC stain
« Reply #8 on: April 10, 2024, 06:08:38 PM »
A test thioether stained nicely with basic permanganate.

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