Sciencemadness Discussion Board - methylamine

methylamine

Magpie - 11-1-2007 at 22:04

A search brought up a huge number of hits for "methylamine" but no thread devoted to it per se.

As mentioned earlier I intended to convert my recently synthesized acetamide to methylamine via the Hofmann rearrangement. This is a very interesting reaction thought to occur through a bridge from the alpha carbon to the nitrogen. (This is apparently the latest thinking as my older books talk about an electron deficient nitrogen and a methide migration.) The overall reaction is:

CH3-(C=O)-NH2 + Br2 + 4NaOH --> CH3-NH2 + Na2CO3 + 2NaBr + 2H2O

Attached is a picture of the apparatus I used for the 2nd step in the synthesis where the acetobromoamide (which is yellow) is being added to aqueous NaOH held at 80-90C. A lot of small bubbles were evolved. I assumed this was CO2.

Once the acetobromoamide was added the pot was heated to evolve gaseous methylamine which I absorbed in some water and then in 6N HCl. During this step I removed the stirrer hotplate and used a bunsen burner to get better heat control. When I get the methylamine hydrochloride isolated as crystals I'll post a picture.

[Edited on 13-1-2007 by Magpie]

methylamine.jpg - 121kB

kaviaari - 12-1-2007 at 04:28

The setup is so so so nice that I would like to hug it

Furch - 12-1-2007 at 04:51

I have to agree with that... Lots of cred to you, Magpie

Anywho... You're distilling off the methylamine freebase and trapping it in concentrated HCl (aq)... It's funny that you succeed in this approach of isolating the methylamine HCl, as I've tired the very same thing, and failed... Why did I fail, you ask? Well, it seems the methylamine just didn't want to stay in the aqueous solution - it forms MeNH2*HCl and espaces the HCl (aq) in the flask in form of a fish stinking mist.

Have you experienced the same problem, and if so, what precautions did you take? If not, why are some chemical phenomena unique for my laboratory? :-P

Sincerely,
Furch

garage chemist - 12-1-2007 at 04:53

Very nice! I see that you used the lab procedure with bromine instead of the ghetto procedure with bleach. Respect.
I am curious how you made the bromine necessary for it, and what was your sorce of bromide? Did you find OTC NaBr, or did you buy a bromide salt from Ebay?

I would say that the bubbles you saw were the methylamine gas, since CO2 cannot be evolved from such a strongly basic solution.
It could also have been nitrogen, from side reactions like oxidation of ammonium ions by hypobromite.

No amateur chemist that I have heard of has prepared methylamine this way- they always use the hexamine/HCl or formaldehyde/NH4Cl route, which are notoriously messy and are known for the very tedious workup necessary in order to obtain a reasonably pure product.

But you will also have to do a selective dissolution of methylamine-HCl from ammonium chloride, since side reactions also produce some ammonia. Inform yourself in Rhodium how to do that, or ask Organikum.

A simple test to confirm that your product consists primarily of methylamine is to heat some of the hydrochloride with NaOH solution to evolve the freebase gas and try to light it.
Contrary to ammonia, methylamine gas is flammable, and the commercial 40% aqueous solution bears a "flammable" warning sign. I tried lighting a few drops of it, and it indeed burns with a blue flame similar to that of methanol.

Magpie - 12-1-2007 at 09:27

I prepare bromine by mixing NaBr from spa suppliers (local OTC) with H2O2. Then in a setup very similar to the one for methylamine I carefully and slowly add con H2SO4 from a dropping funnel. This produces bromine very nicely as a distillate and all under good control. I then place it in a bottle with TFPE cap liner. I place this in my freezer and try to use it up soon as I just don't like having it around. The ratios I use are: 51.5g NaBr, 83mL H2O2 (6%), and 20mL con sulfuric. This is stoichiometric IIRC.

GC I'm sure you are right about all those bubbles. They probably were methylamine and I lost a lot that way as I didn't have my absorbtion trap set up until I had added all of the acetobromoamide. I did capture some as a gas this way, however, and presented it to family members for a quick smell. Both thought it smelled like the seafood section of our local grocery.

I followed my old school procedure on this but next time will be capturing the methylamine from the beginning. I don't know how much I actually captured and won't know until I weigh the methylamine HCl. The workup is by drying followed by extraction with absolute ethanol and seems fairly straightforward. I'll let you know how it goes.

garage chemist - 12-1-2007 at 11:32

You should have added the N-bromoacetamide solution to the room temp. NaOH solution, and then heated to induce the reaction and drive over the methylamine gas.
As I read above, you should definately catch it in water (but don't stick the tube into the water, because of suckback- let the tube end a cm above the water, and swirl the water from time to time) instead of HCl, because HCl vapors would combine with the gaseous methylamine and form a smoke of methylamine-HCl instead of an aqueous solution of it. You can always neutralize the solution later.

Furch - 12-1-2007 at 12:42

Garage chemist,

THANK YOU for bringit it up as well... I tried explaining that phenomenon in my previous post, but didn't get any response.

Are you positive that bubbling methylamine freebase through water (shouldn't a magnetically stirred flask of water do even better, rather than just letting it sit there and swirl it occasionally?) will dissolve the majority of it? How do you know it doesn't just drift away, out into the atmosphere? I mean, since it's invisible as the freebase... It's hard to tell.

- Furch

garage chemist - 12-1-2007 at 12:53

Methylamine is even more soluble in water than ammonia (on a weight basis), and a liter of water already dissolves 700 liters of ammonia.
Why do you think that the strongest ammonia solution you can buy is 25%, while the strongest methylamine solution you can buy is 40%?
The methylamine will dissolve vigorously in water, so much that you should NOT bubble it in because suckback will happen.
Let the hose end about 1 cm above the water surface. Magnetically stirring the water is also beneficial, but it will dissolve fine without it.

Magpie - 12-1-2007 at 12:59

Furch - I didn't mean to ignore your problem - I just had not seen any fog with my experiment as I used a submerged tube. And yes GC I did have some suckback but was lucky to catch it before it got very far up the condenser.

A method promoted in a more modern lab manual I have might prove beneficial here, ie, the inverted funnel, for absorbing a gas in water. This is used to absorb HCl and HBr fumes and I don't know why it wouldn't work with methylamine as well. It eliminates suckback by having a small air gap along one edge.

GC what you are say about holding the temperature down to room temp until all the N-bromoacetamide is in makes sense. The reaction is exothermic but a cold water bath would likely do the job. I wonder why my old (1962) procedure specifies holding a temperature of 80-90ºC?

[Edited on 12-1-2007 by Magpie]

Furch - 12-1-2007 at 13:15

GC, thank for the reply... I'm aware of the respective solubility of ammonia and methylamine... All I'm saying is that it might need some blending before it actually *dissolves* Catch my drift? :-)

Magpie, sorry, I didn't mean to criticise you...

Anyway, that's a great idea with the inverted funnel... What's an even better idea is a couple of glass gadgets I've got lying around... They look like funnels, but where you expect the "mouth" of the funnel to be, there is a glass filter, which finely divides the gass, making tiny tiny bubbles on the outside of the filter, increasing the reaction surface greatly.

This gadget does however not work when leading the MeAm gas through concentrated hydrochloric acid, as stated above

I'll give it a go with water then.

Thanks for the replies, and good luck Magpie!

- Furch

[Edited on 12-1-2007 by Furch]

Nicodem - 13-1-2007 at 02:26

Quote:

Originally posted by Magpie
GC what you are say about holding the temperature down to room temp until all the N-bromoacetamide is in makes sense. The reaction is exothermic but a cold water bath would likely do the job. I wonder why my old (1962) procedure specifies holding a temperature of 80-90ºC?

The reason is simple. The Hoffman rearrangement readily happens at such temperature while bellow that a 'relatively stable' solution of the deprotonated N-bromoacetamide exists. The reaction is indeed exothermic but not terribly so. However, since acetamide has a relatively low molecular mass you can have a higher molarity in the solution as you would have with other amides, hence considerably more heat is evolved that with other amides. More heat, higher temperature, faster reaction, more gas evolution and so on until a runaway. The reaction mixture could then just start boiling methylamine violently once it would get over about 70°C. The other problem is that the amine can get oxidized by the N-bromoacetamide and this is why it is best slowly adding it to the NaOH solution at the temperature where the rearrangement happens relatively fast (>70°C). This way you assure that the formed amine is only minimally exposed to the oxidation environment since the concentration of N-bromoacetamide in the reaction flask will be negligible all the time while the formed methylamine forms in a controlled fashion.

Magpie - 13-1-2007 at 10:51

Thanks Nicodem for that information. I agree that the heat generation was not excessive. I did have trouble reading my thermometer because of fogged adapter glass so I'm not sure I had it under the best control. I should have put some flame heat to it to unfog. Or better yet get a thermometer with a smaller range that more suits this experiment.

My procedure also says to start collecting the methylamine gas after all of the N-bromacetamide has been added. Is there any reason why it could not be collected as soon as one sees bubbles being generated in the pot?

Magpie - 15-1-2007 at 14:00

My efforts to obtain methylamine HCl from the Hofmann rearrangement of acetamide were not really successful. I think a fair amount of methylamine was generated but my capture and workups weren't successful.

I obtained quite a bit of solids after drying the absorbing solution on a water bath, which took hours. I then extracted this with hot absolute alcohol. Most of the solids (80%) did not extract. According to my procedure this is NH4Cl. What did extract had a yellowish color and took forever to dry on a steam bath followed by a drying oven at about 100C. Melting point of the poorly defined crystals was 190C vs the literature 226-8C for methylamine HCl. I could post some pictures but I don't see the point.

Misanthropy - 15-1-2007 at 15:15

Dimethylamine?

Quote:

Originally posted by garage chemist
No amateur chemist that I have heard of has prepared methylamine this way- they always use the hexamine/HCl or formaldehyde/NH4Cl route, which are notoriously messy and are known for the very tedious workup necessary in order to obtain a reasonably pure product.

Messy? Tedious? Not in my experience. Patience & recrystalization from alcohol yielded quite a nice looking, large flake crystalline mass with a yellow tint. Easily seperated from the NH4Cl. No problem. The yellow tinted, stubborn substance was isolated from the methylamine hcl with repeated washings & seems to be dimethylamine, as I had read elsewhere.

The methyalmine hcl now seems clean as can be, white, fishy, hygroscopic snow.

Am I the only one or what???

BTW, Magpie: You've made a very nice setup for yourself there. *green with envy* :cool:

[Edited on 15-1-2007 by Misanthropy]

[Edited on 15-1-2007 by Misanthropy]

pantone159 - 15-1-2007 at 15:27

I've heard that dimethylamine HCl is soluble in chloroform, so you could remove it that way.

Magpie - 15-1-2007 at 15:32

Thanks for that info misanthropy. I had noticed when I did the orginal extraction with absolute ehtanol that a fine white "snow" had formed when the ethanol just began to cool. So, at this very moment, I'm recrystalizing the yellowish solids. This time I will separate those crystals by filtration before drying and see if that helps my melting point.

BTW if you guys want to see some nice glassware setups check out Stefan's (garage chemist) phosphous pentachloride post on versuchschemie.de. Even if you can't read German (like me) it is fun to look around.

[Edited on 15-1-2007 by Magpie]

Magpie - 15-1-2007 at 19:38

The yellowish solids were recrystallized in aboslute alcohol, Buchner funnel separated from the yellow mother liquor, and washed with a little cold ethanol. They were white as the driven snow and I was very hopeful (see photo). So I dried them for an hour or so at 100C them determined the melting point. It was in excess of 250C.

I then place some of the powder in a mL of water (it dissolved instantly), checked pH (it was 6) and then added 10% NaOH to a pH of 8. There was no smell of methylamine, even after heating. So I have to chock this one up as pretty much a failure.

fine white snow.jpg - 13kB

pantone159 - 15-1-2007 at 20:00

Could pH 8 not be high enough???

What else could the stuff be? - even if NH4Cl it should smell when basified, right?

Magpie - 15-1-2007 at 20:26

I added some more crystals and brought the pH up to 10. I now get a faint smell of ammonia. But that is supposed to decompose at 220C. Its times like this that it would be nice to have an FTIR.

garage chemist - 17-1-2007 at 07:56

Very strange!
Did you check if the HCl you used for neutralization was pure? Does it leave a residue upon evaporation?
Did you boil the reaction solution to expel the methylamine gas?
Did you start collecting the gas from the beginning, as it is most advisable?

You could extract the white solid again with hot 99% IPA, ammonium chloride ought to be insoluble in there as well and it is not so important to have anhydrous solvent and solid as it is with ethanol.
The IPA extract is then reduced and allowed to crystallize.

[Edited on 17-1-2007 by garage chemist]

Magpie - 17-1-2007 at 09:58

Yes this experiment produced some expected and some unexpected results. My major mistake was probably not collecting the methylamine gas from the beginning as I was just blindly following the cookbook. Yes, I did boil the basified methylamine HCl. My HCl is just muriatic acid so is likely not the purest. Someday I will do this experiment again to see if I can get good results. Thanks for everyone's comments and suggestions.

garage chemist - 17-1-2007 at 10:42

You might try the well known hexamine/HCl or formaldehyde/NH4Cl method if it turns out that nothing useful can be obtained from your white solid (but don't throw it away! Try to purify it first).
I have reviewed the Rhodium methods and found that it isn't that difficult to get a good product if IPA is used for the extraction instead of ethanol.
The yields are not so good (around 50%) but the precursors are cheap and OTC.

bio2 - 17-1-2007 at 17:07

......This gadget does however not work when leading the MeAm gas through concentrated hydrochloric acid, as stated above ......

Works for me, nothing wrong with a little MeNH2.HCl fog in the
flask. A wide bubbler tube with a large volume just below the surface prevents suckback.

The 15% HCl solution has a pH Strip floating in it.

Maya - 17-1-2007 at 17:12

bio2 Wrote:
The 15% HCl solution has a pH Strip floating in it

Duhhhhh

All those pH indicators leach out of the strip in 30 seconds and you are left with just a Strip

[Edited on 18-1-2007 by Maya]

[Edited on 18-1-2007 by Maya]

bio2 - 17-1-2007 at 17:27

Not the ones I use, Macherey-Nagel

They can be rinsed and stored in distilled
water and reused a couple few times as well.

original post?

chemrox - 18-1-2007 at 10:17

Is there an original post on this so those of us new here can catch up? If not could you (magpie) make one we can all follow?
Looks like a simple method and preferable to hexamine in may respects. Also provides a method for obtaining Br2 which is easy enough to buy .. but the shipping costs !!!

Thanks

Magpie - 18-1-2007 at 10:31

@chemrox: I'm not sure what you mean by "original post." Please explain.

bio2 - 18-1-2007 at 13:44

Magpie, How did you make the flask support for the triple
neck I see on the hotplate?

Magpie - 18-1-2007 at 14:26

bio2 this is just an iron ring like you would normally use to support a wire gauze and flask.

It probably wasn't needed in this application as the hotplate itself would provide support. But the ring does distribute the weight better. The reason I had the ring there is so that I could place a gauze on it and heat with a bunsen burner when all the N-bromoacetamide had been added. I was mostly using the stirrer-hotplate as just a stirrer as the reaction is exothermic.

bio2 - 18-1-2007 at 17:46

I see. Try a stainless steel large strainer turn it upside
down and a round bottom flask can be used to imprint
a depression. It will support the flask
directly on the ceramic top or in an oil bath.

[Edited on 19-1-2007 by bio2]

xwinorb - 20-1-2007 at 12:24

Magpie :

To test your supposed methylamine ( not a very scientific test, but fast and easy ) :

Mix a small portion of your final product with a similar portion of NaOH, both dry, powder, over a small dish. Now drip in a drop of water. It should fizz and make bubbles, the smell of methylamine should be very evident.

One word of caution, I think methylamine with a high content of ammonium chloride will smell like methylamine. The smell of methylamine seems to mask the smell of ammonia.

I have used this method to test the first crops of ammonium chloride ( when making methylamine via hexamine ) and they smell mostly like methylamine, despite being mostly ammonium chloride.

Pure ammonium chloride smell different though, exactly like ammonia.

Furch - 20-1-2007 at 12:57

It's not a very scientific way to determine the purity or the presence of one or the other... But in my experience the two taste quite different. We all know the taste of ammonium chloride, and should quite readily be able to distinguish it from that of methylamine... I believe taste is less deceiving than smell in this case.

Note though, that methylamine is poisonous, so only taste very little (less than a milligram), then spit it out immediately.

garage chemist - 20-1-2007 at 16:03

I did a quick experiment with some pure methylamine HCl (made by neutralizing commercial 40% CH3NH2 with HCl and evaporating in a warm place):
I added some 99,5% Isopropanol and boiled for a few minutes, then decanted and let cool. Crystals soon appeared.
However, their amount was not very large. In order to recrystallize MeAm-HCl this way a lot of isopropanol has to be used.
A smart alternative would be to use a soxhlet extractor!

I repeated the experiment with some ammonium chloride instead.
After boiling, decanting and cooling, absolutely no crystals appeared.
So extraction of the crude (dry!) salt with hot isopropanol, preferably in a soxhlet to reduce isopropanol consumption, seems like a good way to purify the methylamine-HCl.

Furch - 20-1-2007 at 16:06

A very good initiative, Garage chemist.

Regardless of your experiment, I agree that IPA is the solvent to use for purifying ammonium chloride contaminated methylamine hydrochloride.

- Furch

pantone159 - 21-1-2007 at 10:37

Has anybody tried using n-butanol for the separation? The OrgSyn synthesis mentions this as good, since NH4Cl dissolves in it hardly at all.

Furch - 21-1-2007 at 11:34

Pantone, in accordance with Garage Chemist's experiment mentioned above, the methylamine acquired from recrystallization from IPA is good enough for any amateur chemist's purposes.

0.6 g ammonium chloride dissolves in 100 ml absolute ethanol, and even less in IPA.

- Furch

Klute - 13-2-2007 at 15:10

Klute's got some acetamide on hand, and wanted to try the hofmann rearrangement to methylamine... Unfortuanly, where he lives, Calcium Hypochlorite isn't available anywhere anymore... Only hypochorite sources are either 10% max sodium hypochlorite solution, or solid sodium dichloroisocyanurate, which gives hypochlorite and cyanuric acid in water... He wanted to try a reaction with 40gr acetamide, with the sodium hypochlorite solution... After some calculation, he realized he need 640ml of that solution for 40gr acetamide, with excess to compensate the solution not being as strong as indicated...
Wouldn't that be too diluted for that reaction? This could mean smaller yields, but at the same time, the exothermic reaction will be much smoother, and letting the bleach react with the acetamide for say 4hours before adding the NaOH could compensate... But damn, distilling with a 1 L flask for 25gr MeNH2... In any case, this really isn't scalable....
So the other possibilty is the dichloroisocyanurate... would cyanuric acid interfer with the reaction? I'm scared so...

Has anyone got experience with using sodium hypochlorite solutions with this recation? Or even dichloroisocyanurate? Could cyanuric acid interfer?

Klute guess nitromethane reduction would be more practicale... Could 10% MeNO2/MeOH azeotrope be used as is in either Sn or Fe acid reductions? In Klute's experience, using 10% azeo kills a Al/Hg reaction... too diluted...
Any advice appreciated

Furch - 14-2-2007 at 04:12

A couple of years ago I reduced nitromethane by Fe/HCl and reflux overnight... The yield was a little more than 50%, but IIRC my workup wasn't as thorough as it would've been today, so you can probably get a better yield out of that particular reduction.

IIRC I used the molar ratios from Vogel's or March's straight off, with a slight excess of everything. Don't remember the concentration of the HCl though... Probably around 10-15% or so.

Sauron - 14-2-2007 at 04:57

The Org.Syn. procedure has the virtue of cheap feedstocks. Hard to get much cheaper than formalin and ammonium chloride.

Switching to nitromethane reduction and you are consuming chloroacetic acid and sodium nitrite instead.

You could also reduce formaldoxime (from formalin or paraformaldehyde and hydroxylamine hydrochloride.)

Or generate methyl chloride from methanol and TCT and ract it with ammonia.

There are routes starting with iodomethane but that is costlier and naking it from methanol and I2 means using a valuable scarce reagent (iodine.)

So take your pick.

Furch - 14-2-2007 at 05:29

The nitromethane route is superior to both formalin/NH4Cl and methyl chloride on ammonia in that reduction of nitromethane gives mono-methylamine period, no di- or tri-variations, which without a doubt methyl chloride on ammonia would, and also formalin/NH4Cl.

The same polyalkylation problem would arise from using any methyl halide on ammonia, including methyl iodide.

IMHO, a rule of thumb is that alkylation of amines by alkyl chlorides is almost always the last and desperate way out of a synthetical dilemma.

If it's purity you want, then I recommend you go for the nitromethane or acetamide route. If it's quantity you want, go for formalin/NH4Cl, then recrystallize from IPA.

nightflight - 14-2-2007 at 10:59

What about the Hexamethylentetramine with HCL synth? -Are there any write-ups?

The Hex is OTC and readily available, a little more expensice than NHCl4, though, but it compensates, if your supplier is on the expensive site, for Formaldehyd.

Sauron - 14-2-2007 at 11:01

Actually I have more use for dimethylamine and methylamine.

Here dimethylamine is controlled while methylamine is not.

Rather silly reallt.

You are correct about MeNO2 giving only the monomethylamine but I would not be very happy with a 50% yld. in reduction step.

And in the nitromethane thread so many are griping about having trouble getting sodium nitrite. At least I don't have that hassle, and I have chloroacetic acid on hand as well. Though next time I think I'll buy a few kg of the sodium salt.

Furch - 14-2-2007 at 11:26

Of course, I used formalin/NH4Cl as a joint name for all the formalin/ammonium/hexamine variations... After all, they are principally the same (hexamine is hydrolyzed to formalin and ammonium chloride in an acidic environment).

You should be able to find the hexamine route easily in Rhodiums archives.

Sauron, that is indeed very weird! Here nitromethane is OTC, and quite cheap too... In contrast to chloroacetic acid and sodium nitrite. I'll probably research the Fe/HCl reduction futher sometime, as I'm quite convinced the yield could be significantly increased if more effort is put into it. I'm a bit puzzled that nobody has done a serious write-up on that particular topic... After all, all the chemicals are dirt cheap (except maybe MeNO2 in some cases).

The difference in legislation of precursors when looking at several countries never ceases to amaze me!

Rosco Bodine - 14-2-2007 at 11:47

You should get way more than a 50% yield from nitromethane via reduction using aluminum isopropoxide or perhaps aluminum amalgam directly , or with some other alcohol perhaps methanol or ethanol ....or perhaps using toluene or xylene for a solvent to moderate the reaction . I know aluminum amalgam does the trick , but I don't remember the exact conditions .

Klute - 14-2-2007 at 13:59

In my country, formalin is hard to get in decent quantity.. Pharmacies will give you 25-50ml maximum... Also, no hexamine tablets have been found yet, people in specialized camping shops don't even know what they are... From what I heard the workup is quite a hassle... (takes time)
As Klute hasn't got much time, he will not try the sodium hypochlorite hofmann rearrangement right away, but go on the MeNO2 reduction... Max concentration of the nitro is 15%, so when distilling about 500ml of racing fuel, he gets roughly 350ml 10% MeNO2/MeOH azoetrope, 35ml nitromethane, and 45gr oil as residu...
He is planning on doing an Al/Hg with 35ml pur nitro and perhaps 100ml of the azeotrope which would give a 45% nitro solution... In his experience, 10% azeotrope kills an Al/Hg reaction... refluxs dies off..
Apart from the MeOH of the fuel, EtOH will be used as solvant, as this distills much more MeNH2... after reaction is done, 30% NaOH will be added and alcohols distilled and neutralised with conc. HCl and evaporated to recover the HCl salt...

[Edited on 14-2-2007 by Klute]

Sauron - 14-2-2007 at 17:35

Yep, @Rosco, I agree, which was why I said I'd be disappointed with that yield. I started off my tenure as a RA doing Al/Hg reductions in anhydr EtOH back in the Middle Ages, c.1975, before moving on to LAH/TiCl3 in THF (McMurry's Reagent) and the yields were much better. I'd be surprised if a whole shelf of reducing agent options wouldn;t work and work well. Al amalgam is perhaps more kitchen friendly than most...if one were crazy enough to work with HgCl2 in the kitchen.

Bottom line, it shouldn't be hard to find a quantitative prep from MeNO2 in the lit. If you're going to use a valuable reagent to make a somewhat less valuable one, best be efficient about it.

Personally I still think one of the more direct approaches makes more sense as it is not that hard to seperate out (Me2)NH2 even by iterative processes. If rigorously pure MeNH2 is reqd, and I don't know why it would be, then it is time for HPLC prep scale 20 g sample size and a few thousand t.p. seperation in an hour or so. Crank up the old Waters 4000 and Millenium32.

not_important - 14-2-2007 at 17:58

Note that the Hofmann route has an alternative method, where the amide is reacted with bromine and then with concentrated aquous base. This gives a much more concentrated solution. Chlorine could be used instead of bromine, but is harder to deal with.

If you'ev cheap acid, HCl or H2SO4, then you could neutralise the reaction mix, concentrate or even evaportate it, then add enough concentrate aqueous NaOH to liberate the amine whic you distill off. If you use HCl, you could extract the amine hydrochloride with hot alcohol, as the inorganic produces have low solubilites in alcohols. The amine sulfates have lower solubilities in alcohol and do not extract as well - need a proper extractor to do the job.

Furch - 14-2-2007 at 19:17

As I mentioned in the post where I claimed success with the Fe/HCl reducing system on nitromethane, I was nowhere near as thorough in my workup as I am today. I also wasn't as experienced nor as knowledgable (no hubris intended) as I am today. That experiment was merely intended to prove to myself that it was possible to reduce aliphatic nitro compounds with iron in acidic media, and I didn't even follow up on it to optimize the procedure. I see no reason whatsoever why the procedure, if performed correctly, would not give a quantitative yield.

So, to conclude, on my part, 50% was the yield I got on that particular occasion... That doesn't mean the ultimate yield for the procedure is 50%.

Al/Hg is a given if you ask me... You can't fail. Superior to the Fe/HCl in many ways, except for the mercury of course...

Peace out.

Organikum - 15-2-2007 at 12:38

We had something here:
http://www.sciencemadness.org/talk/viewthread.php?tid=1261#p...

Some old textbooks tell that extraction with 95% EtOH is enough to yield MeAm of 98%+ purity, so I wouldnt really worry about some water in a IPA extraction.

Methylamine crystals from alcohol just look completely different then ammonium chloride (see picture in the linked thread). So just forget everything what looks like a white powder.

There was a funny "synthesis" of MeAm from formalin and ammonium chloride on Rhodiums page where large amounts of ammonium chloride were depicted as "pure methylamine.HCl" - a good laugh. Had many pictures though and impressed for sure many. And mislead them nicely. Shows that this page wasnt such a bummer and that Rhodium was anything but a good chemist - more an adolescent flaming Eleusis who was in jail and couldnt even respond anymore.

btw. did you know that Rhodiums real name was posted on ADC (dunno if its still there), when talk was about Strikes trial? XXX from Sweden?
And somewhere there was even Osmiums real name and email once, where was this?
Did I mention lately that I still miss a COMPLETE hive archive? With MaDMAx´s posts and those of some others which were stolen already before it went down?
If it wasnt for PolySAM´s madness I would have exposed them thieves a long time ago.

And: Extraction of MeAm.HCl from a heap of ammonium chloride is a bitch, preseparation by crystallisation is a good idea, the textbooks and articles didnt make this up for fun....

[Edited on 15-2-2007 by Organikum]

Furch - 15-2-2007 at 16:36

Organikum, why would you go and post something like that? Just because someone has done something less ethical on the Internet, which would in this case at most result in an insult to another person on the Internet, that doesn't justify that you try and contribute to exposing their real life identities. That is weak.

On the other notice, what do you mean when you say that extraction of methylamine*HCl from a heap of ammonium chloride is a bitch, when you earlier in your post state that 98% purity can be obtained from simple recrystallization from EtOH, and even better from IPA (which is of course true)?

Someone on this forum tried to recrystallize ammonium chloride from boiling EtOH and got 0.6 g upon cooling, from what I think was 100 ml EtOH, and when repeating the whole thing with 100 ml boiling IPA, he got no crystalls precipitated at all. That's good, yet old news! :-)

Organikum - 15-2-2007 at 18:20

Quote:

Originally posted by Furch
Organikum, why would you go and post something like that? Just because someone has done something less ethical on the Internet, which would in this case at most result in an insult to another person on the Internet, that doesn't justify that you try and contribute to exposing their real life identities. That is weak.

Thats not only weak but it is disgusting. But do have any other idea how to retrieve the information contributed by many to the-hive and stolen by few in a even more disgusting scam (dont forget the download restrictions imposed before!) besides plain blackmail? You are welcome for I have not - I ran out of ideas and of goodwill. And I am well aware that I expose myself to retalation - on the net and in realworld. But I am not afraid on the net and I completely reorganized my realworld settings so I dont have to worry about this either. I would not have dared this if otherwise - Osmium IS a dangerous asshole.

I AM NOT WILLING TO GIVE UP ON THIS. NEVER.

Quote:

Originally posted by Furch
On the other notice, what do you mean when you say that extraction of methylamine*HCl from a heap of ammonium chloride is a bitch, when you earlier in your post state that 98% purity can be obtained from simple recrystallization from EtOH, and even better from IPA (which is of course true)?

Try it and you will see. Its just not so easy to dissolve methylamine.HCl out of a heap of ammonium chloride with which it was cocrystallized. Why? What do I know, encapsulation?, common crystal lattice?, Magic? I dont give a fuck, I tried and saw, others tried and saw the same and textbook procedures point in the same direction. Of course you will aleways find somebody on the net who found an easy way to do this better then Vogel or Gattermann. Usually thats just bullshit of course, but its so COOL!

/ORG

Furch - 15-2-2007 at 20:58

Alright... I wasn't even aware that anything was stolen from the Hive, and to be honest, I haven't even looked into the Hive archives that thoroughly since it shut down. My point is that your critique may very well be accurate (you seem to know a lot more about it than me). But still I urge you not to try and blow peoples anonymacy. It's one of the privileges at least I, for one, enjoy on the Internet... At least to the extent that it is possible these days.

Concerning recrystallization of MeAm from a heap of ammonium chloride - I find the Orgsyn method (Organic Syntheses, Coll. Vol. 1, p.347 (1941); Vol. 3, p.67 (1923)) quite functional actually. I dried the mixture of products over concentrated sulphuric acid in a dessicator, went at it with a mortar afterwards, then started boiling IPA (instead of EtOH as in the article). It smells like methylamine, it behaves like methylamine, the supposed ammonium chloride sure as hell tastes like ammonium chloride, and yeah, you get the picture

chochu3 - 16-2-2007 at 00:19

Furch how did you work up the nitro reduction of nitromethane using iron and hydrochloric acid if you don't mind telling?

I made methylamine by this route and I remember using IPA to purify it but I don't remember the work up I used to get rid of the iron chlorides and such.

[Edited on 16-2-2007 by chochu3]

Furch - 16-2-2007 at 02:10

It was a long, long time ago, and all my notes are gone... But I remember doing it sans alcohol - i.e. water only. When the acidic reduction seemed complete (I left it to reflux for at least 16 hours), the whole mess was made basic with NaOH, then reflux was continued for more hours... During the entire reaction a hose was lead from the top of the condenser down into some kind of solvent in a beaker with magnetic stirring.

I would've done it very differently today, but as I've mentioned about five hundred times by now, the cause of the experiment was to confirm that it worked at all

I don't recommend that "work up" - make up your own instead... It's probably a lot more efficient!

Ephoton - 21-2-2007 at 21:33

nitromethane can be aquired otc in asia my friend. best you take up remote control car racing as a hobby.

franklyn - 16-10-2012 at 21:43

On article page 1664 ( 3rd pg of pdf ) under the heading Alkylureas
" It was found that methylurea and 1,3-dimethylurea reacted with ammonium sulphamate
in a manner analogous to that of urea. Methylamine was isolated from the reaction mixtures."
This is also mentioned in the opening abstract , table IV does not show this perhaps an ommision ?
http://www.sciencemadness.org/talk/files.php?pid=262451&...

.

Hawkguy - 10-1-2015 at 16:43

I thought methylamine gas dissolved nicely in water, so why are you guys doing it in HCl?

greenlight - 10-1-2015 at 20:38

Methylamine gas is usually dissolved in water to make 40% aqueous solution or sometimes methanol but I think they are referring to methylamine hcl, the hydrochloride salt form.