http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0347 (http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0347)
https://www.thevespiary.org/rhodium/Rhodium/chemistry/methylamine.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/methylamine.html)
. And other posts in the TFSE such asPost 209576 (missing)
(terbium: "Re: Methylamine; So many problems? Is it the Altitude", Newbee Forum):You want an excess of the ammonium chloride to prevent the methylamine that is formed from going one step further to form dimethylamine.
Regarding your procedure outline, you will probably need to filter ammonium chloride twice. The idea is that the MeAm will have trouble crystallizing if there are nh4cl crystals present. However, all of the nh4cl is not likely to precipitate the first time unless it is very concentrated, but you dont want to concentrate it so much that your MeAm co-precipitates along with the Am.Hcl. Vogel's procedure (in the post above) which reduces to half the volume after the initial cooling and filtering is a good guideline. Once all the nh4cl is precipitated and removed some MeAm.hcl will crystallize on standing if it is concentrated enough.
An additional tip is that a good way to recognize whether the salt is nh4cl or MeAm.hcl is that MeAm.hcl will feel slimy and dissolve if a small amount is rubbed between the fingers, because of its hygroscopic nature, while the nh4cl will feel gritty and not dissolve.