extracting dimethylamine hydrochoride

[r2e3]

swim has been making methylamine hydrochoride for obvious purposes and has up till now thought that dimethylamine HCl was just a pain in the ass impurity.
but upon further reading swim has seen that it is a reageant used in the manufacture of dmt from indole acetic acid.
now swim assumed that DiME.HCl was mainly soluble in chloroform. the residue the remain after Me.Hcl recrystalisation was deep red brown - so swim thought hey - dump it into the chloroform rinse he had already accumulated and hey presto - more DiMe.Hcl. But upon further research today - and after kicking his self at least 3x - ie all amines are highly soluble in water - duh! but it is also soluble in ethanol and insoluble in ether.
now having said all that - do any of the more experienced bees have a practical method of extracting the DiMe.Hcl?
REcystalisation in ethanol? surely that would leave all the crap in that was soluble from the first Me.HCl recrystalisation..
perhaps there is a ratio between how much seperates from the organic to the organic phase.
swim realises that there are calculations that can be done - but when it comes to calculations of that nature 1. its been 10 years at least since swim looked a them a 2 his maths skills were crap to begin with

a little help anyone?

[armageddon]

Ever heard of "solid-liquid"-extraction? Or do you know how a soxhlet works?

for separation of mono- from dimethylamine, crystallize your amine salt mixture, dry thoroughly, then

a) extract with alcohol (by boiling the salt mixture in several portions of alc which are then combined) to separate ammonium salts (insoluble in alc), then concentrate/cool the combined alcoholic extractions to get methylated amine salts.

b) extract these salts (after drying of course) with chloroform (maybe DCM works too) in the same manner, to separate dimethylamine from methylamine (diMeAm is soluble in ChCl3, MeAm not)

c) concentrate combined extracts to get pure NH4Cl (left over from beginning), CH3NH3Cl (left over after CHCl3 washes) and (CH3)2NH2Cl (from concentrating/cooling the combined ChCl3 portions)

d) repeat as necessary

e) There's no special knowledge behind it - so next time UTFSE if you want to know something like that!
(search button, top left)

Greetz A

[r2e3]

yes - i have heard of solid/liquid extraction and used it. i have also heard of soxhlet and evne looked into it but again would have to spend more money on specialised glassware.

you are incorrect when you say there is no specialised knowledge behind this process.Ask a Abo in the outback to to do it (me) and I think you'll find he may run into a problem or 50

thanks for the pointers - they are helpful and I can work on the 'non specialised' details of organic chemistry - harks back to the old days at Uni when everyone dreaded it... cause it was so easy

i did exactly what you suggested - but dryiing amines isn't exactly easy in its self (in my limited knowledge clearly)
also dimethylamine is soluble in water and chloroform and may well crash out from one phase to the other in ratio X:Y

as for the what seems to be the obligatory UTFSE - if i thought it would be any use - which generally it isn't  (more shit out there than i care to shovel)  - i wouldnt have asked...

thanks for something - or maybe it's just nothing

[armageddon]

Hi!

To perform a solid/liquid extraction, just cover the solids to be xtracted in a flask, cover well with the solvent to be used and reflux (with condenser attached of course) for a few minutes (10-20min. should suffice, but it depends on the solvent/solubility of the desired compounds of course). After reflux, cool down and pour off/filter the solvent and keep it. Repeat the reflux in solvent a few times (2-3 times) with fresh solvent, every time collecting the solvent. Then, combine the solvent portions, concentrate the combined portions (through distillation) and cool slowly to get crystals of the desired/extracted compound. All other solid substances stay in the flask/filter funnel..

The solvent should have the ability of dissolving the desired compound very good, but the undesired other things should ideally be insoluble in it.

In the case of methylamine and dimethylamine, there are two possible solvent groups: alcohols and halogenalkanes. The alcohols dissolve methylamine*HCl good to very well, and the halogenalkanes dissolve the dimethylamine*HCl very nicely and leave back the MeAM*HCl.

Let me repeat: to remove dimethylamine from methylamine, DCM/chloroform should be used, and to remove methylamines in general, they are extracted with alcohol. Hm, seems we aren't closer now than before..

Maybe you could use the different solubilities of methylamine*HCl and dimethylamine*HCl in alcohol: with several careful recrystallizations, it should be possible to accomplish the separation of these two alt least partially. But I sadly dunno which of the two has higher solubility..

Concerning "UTFSE": I don't believe you - because I did promptly find the following   :

Post 488683

(Organikum: "For the vindication of Eleusis - Methylamine", Methods Discourse) (nice spicy discourse about the different aspects of methylamine production *lol*)

BTW when searching something, it doesn't suffice to browse through the hit list of a search engine - you also have to browse through the texts behind the single links (and not only the first two lines - the whole text!), as the name of a thread/post usually doesn't give you a full overview about its contents...

What you're requesting is sometimes called "spoon-feeding" if I remember correctly  

BTW I assume you meant drying alkylamine salts (dimethylamine hydrochloride for example) - this is indeed not easy without any help/equipment.. But can be accomplished by placing the wet salt in an open container and then placing this into a bigger container filled with dry CaCl2 (damp-rid or similar) 5-6cm from the bottom. Close the bigger container tightly and let sit for 3-4 days. After having spent this time in your "home-made dessicator", the diMeAm*HCl should be absolutely dry - but it is hygroscopic now! So open the big container, take out the smaller one and immediately screw lid on tightly. Voilà: dry diMeAm*HCl!

Greetz A

[r2e3]

I have researched the synth of methylamine extensively. some reports say only methylamine and dimethylamine are formed. Both are meant to be white flat crystals but on recrystalisation in butanol - there is also an orange/red residue. After stripping off butanol, i was left with red goo that duely crystalised. i tried to drain off the red goo liquid - some did come off but it seems the the dimethylamine took on water- as you would expect and so resulted - in water this time rather than butanol.

I had my chloroform washing from the menh2.hcl waswh that was deep red too. So i added the now amine containing aqueous phase to the ccl3. all the red crap - ie not dimeth or monometh - crashed into the aqueos phase. I thought this was magic. Clean chloroform containing mainly dimethylamine.

Seeing as dimethylamine is soluble in both h2o and ccl3 - i am wanting to find out to what degree the partition co-efficient?? - i believe, is..

i have not used the hexamine route - have the goodies but have used formaldehyde and ammonium chloride. i see that alcohols prevent the formation of di and tri methylamines.

i want dimethylamine tho!

the thread you posted descibes a reaction i have researched well.

point is - i want the dimethylamine and dont have a clue how to figure out how more readily soluble dimeth is in h2o than in ccl3. I still have the ccl3 washings. I havent stripped it yet. There is a white reisdue already  - so perhaps the di meth is prefernetially soluble in the ccl3. I will do the expt today - stick it in the freezer 1st and see if that does the trick :-)

thanks for the patience - and yes spoon feeding - but as a newb - i do my best find out the relevant info but I am not a chemist by trade.

i will see soon enough if i have lost the dimeth - but i will have further opputunites...

[armageddon]

Hi!

I'm afraid you lost your diMeAm*HCl as you discarded the "crap-containing" water washes of your (no longer reddish anymore) chloroform - as EVERY alkylamine hydrochloride is FAR MORE soluble in water than in chloroform AFAIK (and it is not unusual for concentrated salt solutions to be coloured, although the salt itself is colourless - the red isn't necessarily an impurity)

So you in fact recrystallized your MeAm*HCl properly, but without excluding moisture - therefore the red goo residue (wet butylOH dissolves more MeAM*HCl than dry alcohol, and your alcohol slowly became wet during standing, so solubility was increased slowly - doesn't help in finishing recrystallizations   ). The chloroform (given that you extracted the crystalline amine salts and not the wet mother liquor; and that it was dried before use) surely contained only dimethylamine HCl, until you added the remaining mother liquor from the MeAm*HCl rextalization - at this point the chloroform contained diMeAm*HCl, alcohol, water and MeAm*HCl dissolved in the water/alc portion. And as you added water, you washed all salts, alc and salt/water solution away - therefore the red colour faded. (Note: DCM often gets red-coloured when something dissolves in it - so the red colouration might be a sign of much amine*HCl dissolved in your CHCl3, too..)

Here is something that might help you understand (merck index, entry "Dimethylamine":

Derivative Type:  Hydrochloride
CAS Registry Number:  506-59-2
Molecular Formula:  C2H7N.HCl
Molecular Weight:  81.55. 
Percent Composition:  C 29.46%, H 9.89%, N 17.18%, Cl 43.47%
Properties:  Deliquesc leaflets, mp 171°.  Very sol in water; sol in alcohol, chloroform. Practically insol in ether.  Keep well closed.  LD50 in mice (g/kg):  1.21 i.v., 2.00 s.c. (Hazard).  LC50 in mice (ppm):  7650 (48 hr), 4725 (14 day); in rats (ppm):  4540 (6 hr) (Steinhagen).
Melting point:  mp 171°
Toxicity data:  LD50 in mice (g/kg):  1.21 i.v., 2.00 s.c. (Hazard); LC50 in mice (ppm):  7650 (48 hr), 4725 (14 day); in rats (ppm):  4540 (6 hr) (Steinhagen)

As you see, your amine salt dissolves more readily in water; a prerequisite for being able to extract from other solvents with water -but why would you want to do this? Purification? Think about it: the MeAm.HCl was only  extracted from solid impurities (NH4Cl) and after concentrating/rextalizing the MeAm.HCl appeared as pure salt - why would you want to "dual solvent extract" the DiMeAm.HCl before crystallizing it? You already did extract "solid/liqid" when extracting the solid DiMeAm*HCl with ChCl3 (most surely leaving behind MeAm*HCl "impurities" if your chloroform was dry)...

Suggestion: repeat your formaldehyde/NH4Cl experiment, but heat under reflux to >190°C (opposite to using alcohol for keeping temp. low) and boil it for some time - and make sure to use a ratio of formaldehyde/NH4Cl that favors dimethylation (more formaldehyde?). Then, after recrystallization of your MeAm.HCl (shouldn't be much if the methylamine procedure was done "wrong" correctly *lol*), extract the obtained crystals with chloroform several times ("solid/liquid xtraction") and combine extracts - should have on a red colour.. Then simply concentrate the chloroform solution with vacuum and cool slowly to get diMeAm.HCl with only traces of MeAm.HCl - to purify, simply extract the solid hydrochlorides again with DRY chloroform - same procedure as MeAm/NH4Cl separation with alcohol solvent, solid liquid extraction and rextalization....

- No water washing/extraction is necessary, just keep out water! It will allow impurities to pass the "insolubility barrier"! -

Besides of your erroneous water addition/washing, the procedure you used looks rather useable for making DiMeAmine*HCl - I'm sure you will get a good crop of it when you try again. Good luck.

Greetz, A

[r2e3]

on cooling to -20C - solution turned cloudy and eventually a white crystalline precopitate formed on the surface of the CCl3. i did a 3x h2o was - so yeah- i did lose a load in the aq washes (~75% at a guess). oh well. my primary objective is to get clean MeNH2.HCl but if  I can turn the 'useless' bye product into something useful for a a separate reaction - ie dMT synth then all the better :-)
I will use my remaining formaldehyde and Ammonium chloride to try and synth the dimeth as you described.
I have hexamine/HCl now for the MeNH2 synth - see if it works any better.

thanks for the input