Methylamine and its aqueous solution

Bushroot · Sat Jul 09, 2005 12:43 pm

Hi!
I just prepared some methylamine HCl from formalin and ammonium sulphate. I filtered off three portions of NH4Cl and then (i suppose) a big chunk of methylamine...
The salt I recieved is wet and yellowish, it becomes lighter when dried on buchner funnel but still yellowish. I have no chloroform to wash it from dimethylamine... Are there any substitutes for chloroform for washing the salt I got? (I did no washing)

How can I prepare an aqueous solution for benzaldehyde \ nitroethane reaction a la Barium?

I took some of this yellow crap and put it in the flask with addition funnel and a pipe with test tube filled with water to catch the gas. Pipe goes to the bottom of test tube, and the neck of the test tube is open to allow the gas flow. KOH saturated solution was added dropwise and gas was bubbled through some water. Most bubbles escaped the neck, but the solution I got smells ammonia.
how i know that the gas solution in the not the ammonia, but methylamine? Is it possible to use obtained solution for nitroethane condensation? Please help!

bio · Working Bee

Sure don't know how one gets hydrochloride from sulphate.

If you did make hydrochloride salt the first 2 crops of MeNH2.HCl should be white and only need recrystallizing. See Vogel for details and there are substitutes for CHCl3 like CH2Cl2 or maybe CCl4 but I have no experience with them.

A little searching will easily find a procedure for aqeous methylamine. Check the Hive files and Rhodium archive.

The base does smell like fishy ammonia but the crystals look much different than the ammonium salt and are easy to tell apart. Perhaps try again, being better prepared and more carefull next time!

Following proven procedures is essential for the first runs unless you want to waste a lot of chemicals and time.

Ephoton · Mon Jul 11, 2005 1:19 pm

nope no subst for CCl3 better way of making methylamine is to use nitromethane
put it through an amalgum or use tin in hcl or some electric method on this site I havent tried yet. put solution with NaOH then bubble amine through solution
to do Henry reaction with dont go aq henry go alcoholic.
the way your making meamine has way to many impurities and is too hard to
purify for my liking.
think of the methylman amalgum then look at methylamines boiling point.
you can do a henry with just about any base.

Ephoton · Mon Jul 11, 2005 1:21 pm

oh buy the way methylamine gave one of my apprentices a nasty sickness that made him turn yellow and spew for a week dont boil it down to purify it unless
you have a full still.

bio · Working Bee

When reducing the volume better to use vacuum so no fumes or at least run a tube out the window or to an inverted funnel barely touching some water. This will absorb them.

The reaction is over when it's ready to "boil down" so the fumes that made him sick would be formic acid which also has a distinctive smell unlike formaldehyde which is quite nasty in itself. Shouldn't be any methylamine gas fumes at all and of course it is very toxic and explosive as well.

There may be better ways for small scale production but the beauty of the HCHO/NH4Cl way is you can make large amounts very cheaply ($10Kg) although it is a lot of work.

Try Organikums alcohol method , speeds it up somewhat and runs at a lower temp (78deg for EtOH)with almost no dimethylamine which is increased if the temp goes higher than 104deg in the usual way.

Bushroot · Wed Jul 13, 2005 2:39 am

thanks 4 the replies!

bio · Working Bee

..... So I got all my MeNH2*HCl in one portion Sad its yellowish .............

Unless it's just a very small amount don't throw it out and start over IMHO.
Redissolve the chunk in 96% EtOH and do a fractional crystallization taking three crops. Save the last crop which has almost all the dimeth till you get some chloroform but I have heard methylene chloride works OK.

This may help you also.

(>100g) MeAmCl/100g water; 35g AmCl (15°C) 66g (80°C)
65g MeAmCl/100g MeOH; 3.2g AmCl (15°C), 4g AmCl (reflux)
23g MeAmCl/100g EtOH, 0.6g AmCl/100g EtOH (15°C)
10g MeAmCl/100g IPA (apx!)

100g of boiling 99% EtOH will dissolve 23.01g (from the Merck Index)

German Patent 468895 15Nov 1928 is the alcohol one I mentioned. Find it thru espnet.

Bushroot · Thu Jul 14, 2005 9:28 pm

good news for me! thanks for the info, bio