Methylamine freebase/HCl salt solubilities

[neopharmaphobia]

Hi. I used TFSE and couldn't find any definitive info on this. I was curious of the solubility of Methylamine freebase and HCl salt in DCM or Xylene. I was curious if either one of these solvents could be gassed with Methylamine gas and then gassed with HCl to precipitate MeAm.HCl, and if so which one would be ideal. Also I would like to know anyone's opinion on the practicality of this, when processing 30-60g (freebase).

[Rhodium]

The solubility of Methylamine freebase in benzene is 105g/L (at 20°C), (and it should be similar in toluene/xylene), and the solubility of the hydrochloride should be negligible in those solvents (at or below room temp), so you should definitely be able to gas it out of there again. Chill the solvent with an ice-bath, as it will heat up both when you gas with MeNH₂ and with HCl.

[neopharmaphobia]

Thank you for your response Rhodium. The experiment was reducing nitromethane with an Al/Hg almagam, and the reaction vapors piped directly into xylene. The gas produced by the reaction smelled as described by people at The Hive, whilst the xylene produced no smell of methylamine (indicating that it was absorbing the gas). Afterward it smelled mildly of the gas. 600ml used to absorb perhaps 46.5g (1.5mol) of MeNH2 freebase, gassed with HCl produced nothing. Placing in freezer for 3-4 hours produces no change. Methanol was expected to be carried over into the xylene, through vapors.

So what I'm asking is, would the methanol interfere with the MeNH2.HCl precip.? When gassing, at first produced no visual change, then a cloudy white gas came up from the interface of the xylene. What else could have affected it? Thanks.

[Rhodium]

So what I'm asking is, would the methanol interfere with the MeNH2.HCl precip.?

Most definitely, methanol and xylene are soluble in each other, and as methanol is a very good solvent for both methylamine freebase and the hydrochloride, then this could interfer with precipitation.

If you have converted all the methylamine to its salt form, then you could vacuum distill off the methanol, and when it's gone, the methylamine hydrochloride will fall out, as there is nothing keeping it in solution.

[armageddon]

I recently tried something similar when I wanted to make methylamine formate: added chilled  MeAm*HCl soln. to conc. NaOH(aeq.) covered with cold cyclohexane in a sep. funnel, shaked well, repeated with fresh C6H12, combined the nonpolar washes, dried them (MgSO4) and added 99% formic 'til neutral - result was a slightly milky solution, careful concentrating (to remove water) and acetone crashing resulted in maybe 0.1g (discarded)...

I would guess that the exothermic NaCl formation caused the nonpolar to warm up too much for being able to absorb enough MeAm(g), and I suspect that upon concentrating, a lot of CH3NH3COOH sublimed/evapped.

Maybe gassing is unavoidable..

Has any bee experience with preparing CH3NH3COOH from CH3NH3Cl? (preferably without having to gas)

Thanks, A