Sidmadra
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Need suggestions for isolating an Amino Acid from Sodium Chloride.
I purchased an Amino Acid HCl salt (Dimethylglycine HCl) online with the intent of neutralizing it and chlorinating it. After neutralization and
evaporation, I've discovered most of the solvents in my lab are unable to dissolve the Amino Acid. I tried Ethanol, Methanol, Isopropanol, Acetone,
Ethyl Acetate, DCM, Chloroform. Even "Glycine" is soluble in Ethanol, but for some reason Dimethylglycine doesn't seem to be.
What I imagined to be an extremely straightforward procedure turned into 15+ hours of lab work of testing different solvents, distilling them to see
if any came over, and so on.
The next thing I am considering is trying to recrystallize it from boiling water, but I really need a way to ensure that no trace Sodium Chloride is
left, because that could cause chlorine generation during the Chlorination reaction. As it stands, my solid mixture is composed of roughly 42g of
Sodium Chloride and 70g of Amino Acid.
Is there some obvious method I am overlooking here? I am not used to dealing with Amino Acids like this.
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AvBaeyer
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What do you mean by"chlorinating" DMG? Are you referring to the acid chloride or some other form of chlorination whatever that might be? More
specifics would be useful.
AvB
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Sidmadra
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Quote: Originally posted by AvBaeyer  | What do you mean by"chlorinating" DMG? Are you referring to the acid chloride or some other form of chlorination whatever that might be? More
specifics would be useful.
AvB |
Hi
I plan to use Cyanuric Chloride to form the Acid Chloride, but what is the relevance of that to isolating and quantifying the Amino Acid? I need to
isolate the Amino Acid no matter what since I only plan to use like 1g of it in the chlorination step.
What other sort of specifics are you interested in?
[Edited on 9-8-2018 by Sidmadra]
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morganbw
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wiki mentions a route to the free amino acid by neutralizing the acid salt with silver oxide.
I am clueless on the specifics but hoped it would give you a direction to look.
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Sidmadra
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Using silver for that purpose sounds pretty expensive for such a cheap amino acid. I'm sure there's bound to be a cheaper solution than that. I'm
going to research a bit more later today.
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UC235
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Did you add an excess of NaOH and now you have Sodium dimethylglycinate? Because that would explain your solubility issue. Otherwise, I see literally
no reason why it shouldn't be extremely soluble in most organic solvents.
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Sidmadra
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| Quote: Originally posted by UC235 | | Did you add an excess of NaOH and now you have Sodium dimethylglycinate? Because that would explain your solubility issue. Otherwise, I see literally
no reason why it shouldn't be extremely soluble in most organic solvents. |
I added at most 1% molar excess of hydroxide, so some of the compound would have been the Sodium Salt, but not the bulk of it. I was fairly precise
with the weight measurements. There's a solubility table online for Glycine and even that is only soluble in Ethanol and Water. I didn't have any
success with Ethanol though for this. Your surprise is exactly how I felt. Amino Acids in general don't tend to have a high solubility in organic
solvents unless they maybe have aryl groups.
I know what I can do. I'll make a ammonia solution in methanol from ammonium chloride and sodium hydroxide with slight excess of ammonium chloride,
filtering off the sodium chloride formed. I'll then use that methanol ammonia solution to neutralize the acid salt directly, which should leave me
with the isolated pure amino acid, as all formed ammonium chloride would be dissolved in the methanol.
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unionised
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| Quote: Originally posted by Sidmadra |
I really need a way to ensure that no trace Sodium Chloride is left, because that could cause chlorine generation during the Chlorination reaction.
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Good luck... any moisture present will get converted to chloride and hence chlorine.
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