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Author: Subject: Good way to Methylamine HCl?
Mendeleev
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[*] posted on 28-11-2004 at 09:55


My point was that, can a solid even have a vapor pressure?



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[*] posted on 28-11-2004 at 10:34


Naphthalene stinks.
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neutrino
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[*] posted on 28-11-2004 at 16:32


Yes it can. To clarify the previous post, naphaltene sublimes a little at room temperature (because it has some vapor pressure) and thus stinks.
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biggrin.gif posted on 6-6-2005 at 16:29
Methylamine & Butanol


Swim made some MeNH3.HCl via Hex and methanol. After removing excess NH4Cl, volume was reduced with vacuum in a water bath untill very very thick. If Swim uses Butanol to extract, some water will come over as well. So what will this water more likely bring with it, methylamine or NH4CL?

Kind regards,
FF
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biggrin.gif posted on 9-6-2005 at 17:21
Methylamine extraction methods


Hi there!

Swim wants to extract Mehn2.HCl with Butanol as easily as possible keeping purity and yield high without going Orange.

Swim added 50g Hex + 155g 30% HCl + methanol + 10g NH4CL set up in a 3 neck 250ml RBF with a packed 250 mm column in a mantle. The methyl formate was distilled over about 3 hours, temp around 31.5 to 36 deg C (I think, can't remember right now). heat was progressivly raised while distilling formate until the reaction temp reached 90 deg C and was kept there for 1 hour. Cooled, filtered, set up in water bath with simple vacuum distilation. reduced till Nh4CL spotted, cooled, filtered, reduced again till very thick and mushy and no more distillate come over.

Now swim is thinking of extracting either of 3 ways;

1) Adding butanol, fractionally distilling azeotrope till dry, decanting then adding fresh dry butanol and simply boiling and decanting. With oil bath at 145 deg C.

2) Adding butanol, boiling decanting, etc pooling, cooling, filtering, distilling the butanol to crash out MeNh2.HCl.

3) The more traditinal method of cooling before it's gets mushy, filtering to collect the MeNH2.HCl and returning filtrate, reducing and pouring into a beaker where it goes solid, then boiling with butanol.

Swim's amine turned orange when using method (1) and no amine collected. That happened in another synth where more HCL was used (100g Hex + 330g HCl) Can too much HCl screw things up? Why did it turn orange?

Regards,
FF
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[*] posted on 10-6-2005 at 02:57


Turning orange happens after my experience when there are ketones present as adulterants. In my case they were in the denat. EtOH.
When the denat. alcohol was pretreated with NaOH and distilled what left back the polymerized ketones - no orange discoloring was detected anymore.

I always used IPA for extraction. First one or two selective crystallations to crash out most ammoniumchloride and the three portions of boiling hot IPA.
Worked ok for me.

Extracting without crashing out the NH4Cl had proven unfavorable as somehow the methylamine doesnt like to get extracted from heaps of NH4Cl (this problem was also mentioned in the literature - yields got much better after I changed procedure - better but timeconsuming).

Also I quitted attempts drying the methylamine.HCl. For my purposes it was enough to dissolve the wet stuff in EtOH, to add HaOH pellets and to distill the EtOH/MeAm over into some more cold EtOH. Some water is ok in an Al/Hg.

Remarkable is perhaps that one older book says thats carefully extracting the MeAm.HCl with EtOH (96%) is ok and residual NH4Cl is not so much one has to bother with for most uses.

NH4Cl precrashed - is understood.
This would make the trip a one solvent only story - much to my liking. Have to try this though.

Final: At Rhodiums page was a big-scale methylamine from formaldehyde/NH4Cl with pictures. Well, I must say that strangely the "methylamine" as depicted in these pictures looked exactly like my ammoniumchloride always looked like. Just if somebody asks himself how MeAM.HCl may look like I can assure that at least in central Europe it does not look like these pictures showed.
(Literature tells that the crystals of MeAm.HCl and NH4Cl differ distinctly and obviously)

/ORG




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[*] posted on 19-6-2005 at 02:16


Damm those ketones! What ratio of NaOH to alcohol do you use to clean? I will use pure 95% EtOH next time. The Denatured alcohol I use has 95% ETOH, 4.25% H2O 0.25%; MIBK, Denatonium Benzoate and Fluoroscein.

I followed your procedure again this time without adding any water, without refluxing first and using a molar equivalent of MeOH. Methyl formate was collected between 31.5 and 36 deg C without refluxing first then holding it there at 90 deg for 1 hour then vacuum distilling, but only got 50% yield after IPA. This was a few days ago and I remember vacuum distilling till rock hard and almost dry before trying to extract with IPA. So does it not matter how wet the crystaline mix is before extracting?

What's the deal with the Vacuum method? Is there a special secret here?
I used Baalchemists writeup. There must be something very very simple here that I still don't understand. 54g hex + 185ml 28% HCL (diluted from 162ml 370g/l 32%) I wish they would write it in grams! not ml. It all dissolved, didn't wait to see hydrolysis, I've used this hex before. Put it straight into a hot water bath and refluxed with vacuum for 3 hours. Liquid temp was 78 deg. Then vacuum distilled for 3 hours untill almost dry. Added 85 ml IPA, boiled for 30 min, decanted, results- maybe 10 flakes of MeHN3.HCL. Jesus.

Summarian, and others at the Hive claimed 80 to 95% refluxing at 65 deg. I believe them, but what's the catch? I've made safrole from catachol but methylamine is still my biggest problem, even the easiest fool proof synths. It's embasasing but true!

Regards,
FF


[Edited on 19-6-2005 by FriendlyFinger]
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[*] posted on 7-8-2005 at 19:32


In this article, methylamine is alleged to have been made by heating ZnCl2, NH4Cl, and MeOH. At 303C.

That is about all that I can say about it, I have no idea what the table numbers on the second page has to do with the yields on the third. The editors must have been able to figure it out. Anyone want to give it a try?

Attachment: jacs_42_2663_1920.pdf (245kB)
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praseodym
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[*] posted on 8-8-2005 at 23:36


Methylamine can actually be obtained by heating aq ammonia with methylchloride.
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skippy
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[*] posted on 9-8-2005 at 10:26


Interestingly, I was just reading about the rxn of alkyl halides with ammonia a week ago and found a bit of info that
implies that the rxn is impractical:

http://www.usm.maine.edu/~newton/Chy251_253/Lectures/Amines/...

"A third method of preparing amines involves the reaction of alkyl halides with ammonia or another amine. The reaction of methyl bromide with ammonia, Equation 3, is a simple example.

While reaction 3 looks simple, it is, in fact, tricky to obtain methylamine in good yield. The reason for this is that methyl amine is more reactive than ammonia; as soon as it is formed, it reacts with methyl bromide to produce dimethylamine. This, in turn, reacts with more methyl bromide to generate trimethylamine. Ultimately, tetramethyl ammonium bromide is formed as shown in Equation 4.

The trick required to obtain monoalkylation is to use a large excess of ammonia. By using an NH3/CH3Br ratio of, say, 100/1 or 1000/1, it becomes statistically more likely that a methyl bromide molecule will encounter an ammonia molecule than a methyl amine molecule. Once all the methyl bromide has reacted, the excess ammonia, which has a lower boiling point than the methyl bromide, is boiled off, leaving the methyl amine behind. (Ammonium bromide is also left behind from the reaction of the HBr that is produced in reaction 3 with some of the excess ammonia. This is separated from the methyl bromide during the work-up of the reaction mixture.)"

end quote

Maybe a tenfold excess of NH3 would be OK with purification? I don't know, any comments?
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[*] posted on 9-8-2005 at 22:21


Hmm...true that this reaction has to take place under very controlled conditions. When excess ammonia is used, all methylamine, dimethylamine, trimethylamine and tetramethylamine will be formed. So anyway to separate the mixture, anyone?
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TaurineMonster
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[*] posted on 21-10-2005 at 22:50


I read a synth for this scaled up to 3mol, but now can't find it.anyone have it saved somewhere close?
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[*] posted on 8-2-2009 at 06:44


What is the best way to go about storing and transfering MeAm HCL from its salt form into a gas canister for storage and 99% anhydrous usage. Ive read that 50% of base makes the gas but how does one go about filling canister or tank for use later on?
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[*] posted on 8-2-2009 at 07:31


easy method:

Methylamine Hydrochloride from Ammonium Chloride and Paraformaldehyde

27 grams of ammonium chloride, 30 grams of paraformaldehyde (molar ratio 1:2), and 90 ml of water were gradually heated. At 80°C a clear solution was obtained, and the temperature was maintained at 104°C for four hours. Slightly more than one-third (9.06 grams) of the ammonium chloride was recovered, whilst 18.96 grams of pure methylammonium chloride were obtained. This equals 86% of the theoretical amount. The amount of dimethylammonium chloride produced was not estimated. It is not suggested from the results of this experiment that paraformaldehyde can economically be used on a large scale with advantage, since, quite apart from the relatively high cost, neither formic acid nor part of the unchanged aldehyde can be recovered as by-products.




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[*] posted on 8-2-2009 at 18:11


Quote:
Originally posted by madcease
What is the best way to go about storing and transfering MeAm HCL from its salt form into a gas canister for storage and 99% anhydrous usage. Ive read that 50% of base makes the gas but how does one go about filling canister or tank for use later on?


As with all gases that are condensable at moderate coldness (eg CL2, NH3, Dimethyl ether, butane etc) it is simply a matter of liberating the gas, drying it then re-condensing to a liquid, pouring it into your cold cylinder and screwing the valve on. Once the cold liquid and cylinder warms up the cylinder becomes pressurised and you have the ability to open the valve and remove the gas or inverting the cylinder to remove liquid.
Having little direct experience with methyl amine i can only speculate. Organic amines are commonly dried using NaOH, so fused pellets in a column would probably be dandy. It's boiling point is not particularly low, -6C or something, so dry ice/ethanol in a cold finger would be overkill but practically the easiest. Amines love those transition metals so probably avoid brass fittings and stick with stainless.

edit-you may want to check the toxicity of methyl amine it may be a bit nasty and/or flammable and you should take precautions accordingly.

[Edited on 8-2-2009 by Panache]




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[*] posted on 9-2-2009 at 22:17


Thanks panache great response i still dont get how with MeAm.HCL is in powder form but needs to be in liquid?
Should this be diluted in MeOH or some other liquid.
Still got me stunned.
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[*] posted on 10-2-2009 at 01:56


It is simple to make this primary amine and it doesn't matter which way you make it you are going to get di and tri products
that is why you recryistlize your primary amine with butanol
! dry ethanol works fine to just remember that if you use ethanol with water in it you are going to loose some in the alcohol.
you simply heat the butanol until the primary amine dissolves in and hot filter it leaving di and tri products behind.
when the butanol cools you will soon see your primary amine precipitate before your eyes ! lovely
by the way as one other member said you can't tell the difference between ammonium chloride you will certainly tell the difference when the primary amine is pure. trust me.
and as organikum said you have to seperate the ammonium chloride first.
in relation to storage you can use a vacume desicator to keep it in but i found that it is not needed when your amine is very pure it is very hygroscopic when not pure.
and as for madcease i think you should learn more about chemistry first , i dont no what you are doing with it but i take it you want to do a reductive amination with a ketone or aldehyde if so whether it is hydrochloride or freebase would depend on what reduction procedure you use.


yes methylamine is poisonous in freebase form .

hope this helps regards azo
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[*] posted on 10-2-2009 at 21:00


Azo it doesnt matter what it is used for all i was asking was how to make MeAm.HCL in its gas form and not the salt.
Its alot purer and longer lasting storage as it will not get used just usual experiments.
I know its poisonous but need to know how they get into canister the ones you purchase from shops.
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[*] posted on 10-2-2009 at 23:24


[Edited on 10-2-2009 by azo]

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[*] posted on 10-2-2009 at 23:40
methylamine


http://www.erowid.org/archive/rhodium/chemistry/meth.louisfr...

sorry this is what i meant to give you


regards azo
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[*] posted on 11-2-2009 at 01:41


Thanks azo have read many times but just recently have been thinking about it and still cannot work it out.
Im no chemist as you can tell just an experimentalist and i think by asking someone may have done this before and might have some knowledge to share with me.
I know it has to be in FB form for most reductions but wanting to store in gas canister.
Any help would be greatly appreciated even a PM.

With the hexy method does it make a difference in yield if a weaker concentration of acid is present or stronger? Eg 37% HCL or 28% HCL as you can never be too sure.
Does water in the reaction make a difference or is it mainly to HCL doing all the work.
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[*] posted on 11-2-2009 at 01:43


I have been told by numerous people not to do the hex and hcl relux in stainless steel as it will react with the metal. Is this true or are they just refering to the acid reacting and not the MeAm?
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[*] posted on 30-3-2009 at 00:37


Quote: Originally posted by KABOOOM(pyrojustforfun)  
we should seriously take glycine into account.........
This is something I've wondered about but never seen discussed. Is there any reason that decarboxylation of glycine wouldn't work for this?

Sorry for bumping a somewhat old thread, I don't know how this forum feels about that kind of thing.
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[*] posted on 31-3-2009 at 01:52


Quote: Originally posted by madcease  
I have been told by numerous people not to do the hex and hcl relux in stainless steel as it will react with the metal. Is this true or are they just refering to the acid reacting and not the MeAm?


Source of nascent NH3 and HCl both complexing and corroding materials for transition metal used in stainless steel...




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madcease
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[*] posted on 31-3-2009 at 02:02


Just as i thought. If a solution of Hexamine, HCL, H20 has been added together. One would have thought the Ammonia Chloride would crash out immediately and then reacts.
Have seen a reaction done where no Ammonia has precipitated even after 8 hours which makes me believe maybe the solution of HCL was too concentrated?

Is the HCL acid touchy in regards to this process as ive seen most of them in the past precipitate with AmChloride.
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