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Ghetto TLC: Solvents?

atrollappears

atrollappears

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Hey guys, got some TLC plates and was thinking of running a few with certain *ahem* materials I have around to get an idea of their purity. So, are there easily available solvents I could use? I was thinking acetone for the polar solvent, and maybe butane (if I could get it to stay as a liquid and mix with acetone) or toluene for the nonpolar solvent. Any suggestions?
 
the solvent choice really depends on what youre trying to put through the tlc. you may have better results with ethanol as the polar solvent based on the functional groups in your test molecule. butane also evaporates quickly, maybe try naptha for the non-polar solvent? if you can get your hands on ether, you may want to try that as well. keep in mind toluene is aromatic, naptha is aliphatic, this will also have an effect on your tlc
 
Butane is not suitable as TLC as it's a gas at STP.

Organic solvents that are "commonly availiable" - limonene (orange oil), pinene (turpentine), toluene, naptha/kerosene/ligroin/hexanes/heptane

isopropanol:naptha:vinegar may be a solvent system you can use?
 
FYI many drug molecules are amines and require the addition of a basic component to the TLC eluent to elute properly.
 
I would go for toluene, hexanes, t-butyl methyl ether could work if you get your hands on it. Xylene even could work. The more polar solvents should be easier to get your hands on.

I just did a TLC last week. I used 120mL of toluene, 60mL of DEE, 18mL of acetic acid and 11 ml of methanol for caffeine, acetominophen and aspirin
 
Thanks for the responses, guys.

Cortexiphan said:
FYI many drug molecules are amines and require the addition of a basic component to the TLC eluent to elute properly.
Click to expand...

The molecules I'm looking at are have aromatic groups and are amines: amphetamines and arylcyclohexylamines. So I would have to add a basic component? And since it's aromatic I should use an aromatic solvent, correct? And I will also have to make sure whatever solvents I'm using are soluble in each other I suppose. How about xylene and isopropyl alcohol with NaOH?
 
some blend of naptha:xylene:iProh/naoh 90:9:1 is probably your best bet
heptane can be found in some craft and hardware stores as e.g. Bestine for cleaning paint brushes if naptha is too complex
ligroin/pet ether (60-90c cut) is also acceptable (same shit as hexanes... lol)
dont use methanol as its not very miscible with hexanes/benzine derivs
you may want to avoid using xylene as the shit stinks
 
sekio said:
some blend of naptha:xylene:iProh/naoh 90:9:1 is probably your best bet
heptane can be found in some craft and hardware stores as e.g. Bestine for cleaning paint brushes if naptha is too complex
ligroin/pet ether (60-90c cut) is also acceptable (same shit as hexanes... lol)
dont use methanol as its not very miscible with hexanes/benzine derivs
you may want to avoid using xylene as the shit stinks
Click to expand...

Thx I'll try it out
 
I wouldn't use aqueous ammonia, personally.. water usually fucks up TLC because you form a two phase system in your development chamber... plus its nearly impossible to evaporate. Maybe isopropanolic KOH could work, if you have the alcohol dried really well.

IME you can almost always get good separation with some combination of DCM/EtOAc/MeOH (all three can be distilled from hardware store stuff), even with most alkaloids. Occasionally a base is needed (triethylamine is a good choice), but usually you can get away without it.

The real question is how are you going to visualize this stuff? If you're not working with a UV absorbing compound, you'll need access to something like phosphomolybdic acid to be able to see the spots on the plate.
 
get some Isopropanol and some hexane or Petroleum ether and run you TLC with like 10:90 (IPA:Hexane/PE) for amines it always good to add 1% TEA or DEA (Triethylamine or Diethylamine) but I guess you wont have acces to them =\ so maybe some KOH in IPA should work too

You can colour you plates with a Permangante solution should be easier to get then the Molybdo/Cer(IV) stuff :) and works for most compunds.

Her is a good side for staining solutions:
http://orgprepdaily.wordpress.com/2006/09/27/tlc-staining-solutions/
 
I was under the impression that one can do a crude sulfuric acid and oven procedure as a developer for TLC plates.

Another good stain would be e.g. Mecke/Marquis
 
Roger&Me said:
I wouldn't use aqueous ammonia, personally.. water usually fucks up TLC because you form a two phase system in your development chamber... plus its nearly impossible to evaporate. Maybe isopropanolic KOH could work, if you have the alcohol dried really well.

IME you can almost always get good separation with some combination of DCM/EtOAc/MeOH (all three can be distilled from hardware store stuff), even with most alkaloids. Occasionally a base is needed (triethylamine is a good choice), but usually you can get away without it.

The real question is how are you going to visualize this stuff? If you're not working with a UV absorbing compound, you'll need access to something like phosphomolybdic acid to be able to see the spots on the plate.
Click to expand...

The IPA is >99%. And as far as visualizing, I was thinking maybe a blacklight, but I'm actually liking sekio's suggestion now, since I have those reagents.

sekio said:
I was under the impression that one can do a crude sulfuric acid and oven procedure as a developer for TLC plates.

Another good stain would be e.g. Mecke/Marquis
Click to expand...
 
The other simple stain that everyone can do is sulfuric acid plus oven., or vanillin plus sulfuric acid plus oven, or something like that
 
Great thread, I will be doing ghetto TLCing as well in the future - got the main gear already.
One project would be converting ibotenic acid to muscimol. Probably using an acid can separate the two, right? But if aqueous solvent systems are not advisable, how to use the vinegar? Or shall I drop sulfuric acid in IPA, something like that?
I think ninhydrin will be used for amine staining. Seems like a handy solution when using mostly alkaloids :D But I understand if that is not considered quite ghetto.
 
CuSO4 forms purple complexes with amines, I am told. Probably easier to get a hold of that.
someone said:
Isopropanol/lighter fluid (1:9) works for almost everything - I've tried! Iodine vapor is a very good stain, too. It is temporary though, so you'll have to mark the spots before it evaporates.
Click to expand...
 
Isn't cupric sulfate non-selective for staining all organic compounds, basically? (Would work) ... anyway I cannot easily find info on that, other than that phosphoric acid tends to be used (can probably be substituted I guess) and charring with heat.
Ninhydrin is available to me though.
 
Not that I mean to nag but perhaps you read amide, and I don't even know if tertiary amides are included or if it must be a peptide or primary amide. Probably the latter, I guess the N-hydrogen is involved.
It's probably that when I read organic matter I thought organic in the context of org. chem, but instead it must have been protein.

If not true - and CuSO4 can stain amines, then it's somewhat of an "off-label" and hardly documented application, in that case even more thanks for the insight.

Think about it though, why would people go through the trouble with expensive stuff like ninhydrin if CuSO4 is just as good?
 
Not Voodoo - Workup Notes
[Procedure for removing] Amine solvents (pyridine, di- and trialkylamines): Amines will partition into the organic layer during a typical aqueous workup. However, they become water soluble [if you] wash the organic layer several times with 10% copper sulfate (aqueous and blue). The copper-complexed amine will partition into the aqueous solution, which turns purple. Continue to wash with the copper sulfate solution until no color change is observed.
Click to expand...

I can verify this later I suppose. Sometimes "good enough" chemistry is simply lost to new technologies considered "superior".
 
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