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Topic: TLC visualization  (Read 3203 times)

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Offline kriggy

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TLC visualization
« on: July 21, 2016, 03:39:16 PM »
Hey guys,
Im running arylation of N,N´diacylated hydrazine using Chan Lam conditions and Im wondering if there is a staining solutions that would visualize the hydrazine? I think I could see the product and boronic acid under UV detection but I doubt that the starting hydrazine would be visible. I doubt I could oxidize it by iodine or KMnO4... Could ninhydrin or dragendorf work in this case? I recall there was a book or article that had lots of different staining reagents but I cant find it anywhere
(I could run it on HPLC but that requires some procedures to remove the copper that seems time consuming and impractical due to low scale of the reaction.)

Online Babcock_Hall

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Re: TLC visualization
« Reply #1 on: July 21, 2016, 05:23:58 PM »
There is an ancient but still useful book by Egon Stahl, "Thin-Layer Chromatography."  There isn't anything about hydrazine in the index, however.

Offline orgopete

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Re: TLC visualization
« Reply #2 on: July 21, 2016, 08:02:37 PM »
There is an ancient but still useful book by Egon Stahl, "Thin-Layer Chromatography."  There isn't anything about hydrazine in the index, however.

Old is okay, but ancient? Ouch!

@kriggy
Is doubt a euphemism for failed?



Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Offline AWK

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Re: TLC visualization
« Reply #3 on: July 22, 2016, 02:55:37 AM »
A new spray reagent replacing sulphuric acid in thin-layer chromatography
Tadeusz Zimiński, Edward Borowski
Journal of Chromatography A
Volume 23, 1966, Pages 480-482

"The latter reagent is prepared by dissolving 20 g of ammonium sulphate in
100ml water and adding 4 ml sulphuric acid (d = 1.84)."
Aluminium, silica gel hot plate ~400 C. Used for all non-volatile organic compounds.
AWK

Offline kriggy

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Re: TLC visualization
« Reply #4 on: July 22, 2016, 03:28:17 AM »
There is an ancient but still useful book by Egon Stahl, "Thin-Layer Chromatography."  There isn't anything about hydrazine in the index, however.

Old is okay, but ancient? Ouch!

@kriggy
Is doubt a euphemism for failed?

Kind of. I tried UV and it was slightly visible but not great. Iodine stain worked fine to my surprise.

AWK: thanks, will keep that in mind

Online Babcock_Hall

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Re: TLC visualization
« Reply #5 on: July 22, 2016, 09:02:33 AM »
Ferric chloride/sulfosalicylic acid is one that I pull out occasionally for hard cases.

Offline orthoformate

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Re: TLC visualization
« Reply #6 on: July 22, 2016, 10:32:36 AM »
There is an ancient but still useful book by Egon Stahl, "Thin-Layer Chromatography."  There isn't anything about hydrazine in the index, however.

Old is okay, but ancient? Ouch!

@kriggy
Is doubt a euphemism for failed?

Hi Kriggy,

I think you should try KMnO4.

Ortho

Offline kriggy

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Re: TLC visualization
« Reply #7 on: July 22, 2016, 05:51:48 PM »
Thanks for suggetions guys, both KMnO4 and iodine worked fine and the hydrazine is kind enough to stick to start of the TLC. Another problem seems that its spot is covered by some undissolved copper so it is not clear to see. On the other hand, it seems that its consumed already while there is lot of boronic acid left in the reaction but that is another story. Gonna be fun monday I guess :-D

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