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Author Topic: Methylamine - better yields
Rhodium [Image] posted 05-11-98 05:24 AM
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70 grams hexamethylenetetramine (0.5 mole) and 30 grams
paraformaldehyde (1 mole) was dissolved in 200 ml water
and 200ml 37% HCl (2 moles) was added. The mixture was
slowly heated and the contents was slowly distilled,
and the temperature rose slowly over 1-2 hours to
109_C. During this time, a lot of CO2 was evolved, and
approx 75ml of formaldehyde-smelling distillate was
collected. The solution was concentrated under vacuum
until a lot of solids precipitated, which were filtered
off, and the solution was further concentrated,
filtered etc until everything was crystallized. The
white solids were placed in 150ml warm MeOH, and
filtered. The insoluble portion was recrystallized from
water, to give XX grams of ammonium chloride. The
methanol solution was evaporated and recrystallized
from methanol and washed with acetone, to give a
deliquescent crystalline mass, which was dried in a
desiccator over CaCl2, to give 49 grams of methylamine
hydrochloride (0.72 mole). Calculated on the two moles
of amine nitrogen put into the equation, 36% became
methylamine, and 37% (0.75 mole) became ammonium
chloride. The net yield of methylamine is therefore
58%.
(No, I'm out of chloroform. Can any other solvent
substitute for it when washing away dimethylamine?)
quirks [Image] posted 05-11-98 10:28 AM
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Why not TCE?? It has similar solvent charecteristics
no? That's what I was going to use instead of
chloroform.
quirks [Image] posted 05-11-98 10:28 AM
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Why not TCE?? It has similar solvent charecteristics
no? That's what I was going to use instead of
chloroform.
David [Image] posted 05-11-98 02:54 PM
unregistered
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Rodium, does this method seem to be easier/cheaper/less
work than the NH3 + formaldehyde one? I mean, since you
gotta use NH3 and formaldehyde to make
hexamethylenetetramine anyway. (unless you want to buy
it)
David [Image] posted 05-11-98 02:54 PM
unregistered
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Rodium, does this method seem to be easier/cheaper/less
work than the NH3 + formaldehyde one? I mean, since you
gotta use NH3 and formaldehyde to make
hexamethylenetetramine anyway. (unless you want to buy
it)
Rhodium [Image] posted 05-11-98 04:04 PM
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I just had all the chemicals lyin' around and I *WILL*
convert Hexamine to methylamine! I will I will I will!
As it stands, the method sucks, but at least I managed
to get a decent yield of methylamine from hexamine
after all. But it is far from quantitative yield. I
must find those articles in Bull Soc Chim and Compt
Rend...
Rhodium [Image] posted 05-11-98 04:04 PM
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I just had all the chemicals lyin' around and I *WILL*
convert Hexamine to methylamine! I will I will I will!
As it stands, the method sucks, but at least I managed
to get a decent yield of methylamine from hexamine
after all. But it is far from quantitative yield. I
must find those articles in Bull Soc Chim and Compt
Rend...
Semtex Enigma [Image] posted 05-11-98 06:33 PM
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I take it you had made your own or were using reagent
grade Hex, right? Have you had any success using the
Camping fuel tabs? I haven't been able to SUCCESSFULLY
remove all that other crap from those tablets... do ya
have a procedure to do such a thing? I still plan on
making my own hex once or twice to get the practice,
but I wouldn't mind having 5-10kg methylamine in a
cache in the hills or somethin....
Semtex Enigma [Image] posted 05-11-98 06:33 PM
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I take it you had made your own or were using reagent
grade Hex, right? Have you had any success using the
Camping fuel tabs? I haven't been able to SUCCESSFULLY
remove all that other crap from those tablets... do ya
have a procedure to do such a thing? I still plan on
making my own hex once or twice to get the practice,
but I wouldn't mind having 5-10kg methylamine in a
cache in the hills or somethin....
Rhodium [Image] posted 05-11-98 07:49 PM
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I use reagent grade hexamine, yes. And as I am not
american, I don't know how to purify your camping fuel.
Our european brand "Esbit" is easily purified by
recrystallization from water.
Rhodium [Image] posted 05-11-98 07:49 PM
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I use reagent grade hexamine, yes. And as I am not
american, I don't know how to purify your camping fuel.
Our european brand "Esbit" is easily purified by
recrystallization from water.
Semtex Enigma [Image] posted 05-12-98 01:02 AM
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Do you mean disolve tablet(s) in water filter and save
(1) Liquid or (2) Soild? I would think that if it is
the liquid that needs to be saved, the water would have
to be evaporated, no?
Semtex Enigma [Image] posted 05-12-98 01:02 AM
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Do you mean disolve tablet(s) in water filter and save
(1) Liquid or (2) Soild? I would think that if it is
the liquid that needs to be saved, the water would have
to be evaporated, no?
Rhodium [Image] posted 05-12-98 07:11 AM
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Yes, throw away solid, evaporate water. It would be
simpler to use CHCl3, but it may dissolve the binder
too.
Rhodium [Image] posted 05-12-98 07:11 AM
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Yes, throw away solid, evaporate water. It would be
simpler to use CHCl3, but it may dissolve the binder
too.
adamantane [Image] posted 05-14-98 03:19 AM
unregistered
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You know, maybe the laws of physics are weird here in
Kansas, but the other night Dorothy was whisked to a
land where she made Methylamine from Hexamine campfuel
tablets with near 100% yield in a very short perios of
time, following the proportions that are listed, uh,
somewhere? Maybe on Rhodium's page? In any case, it's
140g hexamine/400mL HCl/100mL ethanol. HOwever the
following modifications were made:
1. scale down factor of 4 (35g hexamine)
2. subst. 99% isopropanol (avail at the drugstore, if
it's a good one)
3. Procedure was as follows:
Pour HCl into bowl. Add Isopropanol with stirring. Add
hexamine in portions with stirring. Heat and CO2 are
released. As soon as all solids are dissolved* boil the
hell out of it to drive off water, HCl, etc. Result is
fast and easy and beautiful.
*This is a modification from the posted journal
procedure, which said to let it sit 8-16 hours. Dorothy
found that letting it stand _decreased_ yield and
increased formation of the white fluffy precipitate
which is almost certainly ammonium chloride.
Soon I will have the results of various analyses of the
product to see how pure it is. However it seems likely
that the only possible contaminant is dimethylamine,
and there can only be a minority of that, even in the
worse circumstances, because each hexamine molecule has
only 6 C's to 4 N's...
Anybody else feel like they might get picked up by a
tornado and sent to a place where they can try to
duplicate Dorothy's dream?
adamantane [Image] posted 05-14-98 03:19 AM
unregistered
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You know, maybe the laws of physics are weird here in
Kansas, but the other night Dorothy was whisked to a
land where she made Methylamine from Hexamine campfuel
tablets with near 100% yield in a very short perios of
time, following the proportions that are listed, uh,
somewhere? Maybe on Rhodium's page? In any case, it's
140g hexamine/400mL HCl/100mL ethanol. HOwever the
following modifications were made:
1. scale down factor of 4 (35g hexamine)
2. subst. 99% isopropanol (avail at the drugstore, if
it's a good one)
3. Procedure was as follows:
Pour HCl into bowl. Add Isopropanol with stirring. Add
hexamine in portions with stirring. Heat and CO2 are
released. As soon as all solids are dissolved* boil the
hell out of it to drive off water, HCl, etc. Result is
fast and easy and beautiful.
*This is a modification from the posted journal
procedure, which said to let it sit 8-16 hours. Dorothy
found that letting it stand _decreased_ yield and
increased formation of the white fluffy precipitate
which is almost certainly ammonium chloride.
Soon I will have the results of various analyses of the
product to see how pure it is. However it seems likely
that the only possible contaminant is dimethylamine,
and there can only be a minority of that, even in the
worse circumstances, because each hexamine molecule has
only 6 C's to 4 N's...
Anybody else feel like they might get picked up by a
tornado and sent to a place where they can try to
duplicate Dorothy's dream?
RatHead [Image] posted 05-14-98 08:15 AM
unregistered
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The possibilties of some 2 carbon skeleton degradation
products exist also. I'm trying to find that info on
the hexamine degradation mechanism.
RatHead [Image] posted 05-14-98 08:15 AM
unregistered
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The possibilties of some 2 carbon skeleton degradation
products exist also. I'm trying to find that info on
the hexamine degradation mechanism.
Labrat [Image] posted 05-14-98 09:59 AM
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Adamantane, what if I told you that adding an alcohol
to the reaction mix with hexamine will lower the yield
of methylamine? But I ain't bullshittin' you! Just
check out the article Werner wrote in the JCS ('18).
Here the author states, that a low yield is bound to be
had from formalin and ammonium chloride, since formalin
contains methanol as an polymerisation inhibitor.
Formaldehyde will react with methanol at a temp of
about 40-50 dg C forming methylal and thus lowering
overall yield. Substituting isopropanol will only make
the acetal-forming easier. Now you see why you
shouldn't mix alcohol in the Hex->Mex reaction?
Labrat [Image] posted 05-14-98 09:59 AM
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Adamantane, what if I told you that adding an alcohol
to the reaction mix with hexamine will lower the yield
of methylamine? But I ain't bullshittin' you! Just
check out the article Werner wrote in the JCS ('18).
Here the author states, that a low yield is bound to be
had from formalin and ammonium chloride, since formalin
contains methanol as an polymerisation inhibitor.
Formaldehyde will react with methanol at a temp of
about 40-50 dg C forming methylal and thus lowering
overall yield. Substituting isopropanol will only make
the acetal-forming easier. Now you see why you
shouldn't mix alcohol in the Hex->Mex reaction?
green_pea [Image] posted 02-08-99 01:59 PM
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Back to the original question Rhod asked about---what
is another substitute for chloroform. If one were doing
the Formaldehyde/ammon. chlor. rxn for methylamine--is
there another substitute for chloroform maybe DCM?
Anyone??
The Cook [Image] posted 02-10-99 03:38 AM
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Oh Rhodium, you are the sickest.
Yep, paraform would definately make this rxn a molar
assload more repeatable.....
I think ppl's problems are the TYPE of hexamine they
use. Military (US) is fine, can be dissolved/filtered
with acetone. But watch out, I got some "hexamine" that
obviously wasn't. (It was trioxane, a.k.a
paraformaldehyde-useful, but deceptive)
Actually, Military trioxane bars (clean out the purple
w/ acetone, scrape off the clear igniter crap first)
are good for your formaldehyde needs....
Yeah, so I'm saying you're both right... I never
understood why people think Methlyamine is
restricted.....
-cook
ChemHack [Image] posted 02-10-99 12:28 PM
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Here in the US, methylamine and its salts are
restricted.
In my opinion, the reason that Rhodium got higher
yields when adding paraformaldehyde is that there is
excess ammonium chloride formed when the hexamine
breaks down. The paraform reacts with this extra NH4Cl.
Of course, I could be wrong.
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