Abacus: If you'd read my post carefully, you would have realized that your proposed separation method is exactly what I did - concentrate, suction filter the solids, repeat - then rinse collected solids with acetone - then reflux them in IPA for some 30 minutes, repeat with fresh IPA, combine IPA xtractions, concentrate, let cool - et voilà...
The ammonium chloride stays in flask as a solid, the MeAm*HCl dissolves in the hot IPA - which is decanted...
BTW abolt: I adapted the workup from a different procedure, which might give you some new thought perspectives about the subject
:
Gattermann, Ludwig: "Die Praxis des Organischen Chemikers" p. 356 ff., (sorry for my bad translation...)
"LEUCKART REACTION
Methylamine through reductive methylation2NH
3 + 3CH
2O ---> 2H
2NCH
3 + CO
2 + H
2O
250g ammonium chloride (4.7 mol) are slowly heated with 570g 35% formaldehyde solution in a distilling flask fitted with downward condenser. The temperature (thermometer reaching below surface of rxn) is slowly raised to 104°C and held there until no more distillate comes over (4.5h from beginning). The distillate will consist of 100-120g water and methanol (from the 35% formalin solution). After cooling down the dist.flask content, the precipitated ammonium chloride is filtered with suction and the filtrate is reduced to half of its volume on a steam bath. After cooling, the NH4Cl is again separated with suction filtering and the remaining liquor is concentrated until it forms a surface skin. After cooling, the MeAm*HCl is filtered out (suction) and the mother liquor further concentrated (residual water being removed with a vacuum exxicator/NaOH(s) or H2SO4). The residue is freed from di- and trimethylammoniumchloride by washing w/chloroform and dried with suction. Together with the first crystallization, 110-125g of crude MeAm'HCl are collected.
To free the crude salt from residual NH4Cl, it is extracted by boiling with 250ml abs. alcohol for 0.5 hours.
The alcohol is cooled, precipitated MeAm*HCl is filtered and the mother liquor is used for another exctraction. After five extractions, one gets approx. 100g (37% of theory).
With the carbinolamines, the hydroxyl group cannot only be replaced by nucleophile C-bonds (like with the MANNICH reaction) but also under reduction with anionic hydrogen - in above methylamine synthesis, this hydrogen is donated by the excess formaldehyde which in turn is reduced to formic acid (formate), which again serves as reducing agent and is being oxidized to CO2. These reactions (especially the first) are somewhat similar to the Cannizzaro reaction, which is discussed later (p. 377).
The unavoidable formation of di- and trimethylamine becomes the main reaction if the formaldehyde concentration is raised, because primary amine is further methylated according to same mechanism (formaldehyde as reducing methylating agent for amines, ESCHWEILER). According to CLARKE better yields can be obtained by adding additional formic acid at the beginning."
The reductive amination of carbonyl compounds, according to LEUCKART, is generally done with ammonia and formic acid (or its esters) or formamide. Primary and secondary amines (often as N-formyl derivatives) and tertiary amines are made, depending on the starting amine and proportions of reagents."
---I think "optimizing" Orgy's procedure would result in exactly the same procedure (no alcohol) - if you compare the yiels you will see the advantage that lies in the given patent (and in using alcohol)....
(and methylformate just distills over too quickly to allow for a slow temp. rise over hours, therefore methanol is bad - and IPA is bad too because the bp of isopropylformate is almost same as the bp of IPA - impossible to separate!)
BTW abolt as you can see, most usable routes to MeAm have been invented by "nazis"... (I think even methylamphetamine is their invention - or was it the japanese? Maybe collective meth overdose in germany/japan caused WW2?
)
Oh, and as I reread my post, I realize that over-alkylation is only a major problem when NO alcohol is used, leading to excess formic acid present - so the presence of ethanol helps also in avoiding the formation of polymethylated amines. "temp is kept low" and "CO2 evolution is suppressed" are NOT the main reasons for using ethanol...
(abolt: your so-called "research" consists mainly of not reading the literature about the topic, isn't it? In fact, doin it without alcohol means no "improvement" but a step backwards... If you would've read some standard organic chemistry book about it, you surely would have realized too that the patent states (and many bees already have proven so) that almost no di- or trimethylamine is formed - in contrast to the standard procedures, resulting in lots of diMeAm!)
A