Monoamine
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Location: Sweden(ish)
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Purifying methylamine HCl from a solution with excess HCl
I have a HCl solution of methylamine and ammonia (mostly methylamine with a little ammonia, presumably), which I got by bubbling methylamine (with
probably a little ammonia contamination) gas into about 6N HCl.
Now the bubbeling is done, but when I test the solution it's still strongly acidic (bright red litmus paper). So I'm wondering how I can best purify
out the methylamine.
First off, if I just boil the HCl off, will it charr the methylamine hydrochloride that's in it?
Alternatively I was thinking of neutralizing the solution with NaHCO3 or ammonium carbonate and then boiling the water off.
The result will be a mixture of methylammonium chloride, ammonium chloride and (depending on the base I use for the neutralization) NaCl.
So then I would just have to dump the solid leftovers into absolute ethanol and warm the ethanol until the methylammonium chloride dissolves in it.
ammonium chloride and NaCl are not very soluble in ethanol. So then I should just be able to filter off the methylammonium chloride in ethanol
solution, evaporate off the ethanol and be left with fairly pure methylamine hydrochloride (which I can then further dry in a desiccator over silica).
Do you expect this to work? How about boiling off the HCl directly so I don't need to neutralize it with NaHCO3? I think that there is only a very
small amount of ammonia contamination at this point.
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bnull
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As far as I remember, methylamine hydrochloride doesn't char. Try vacuum distillation. The worst that can happen is sublimation or decomposition or
both.
In any case, take a look at this thread: http://www.sciencemadness.org/talk/viewthread.php?tid=9139.
Quod scripsi, scripsi.
B. N. Ull
P.S.: Did you know that we have a Library?
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