@Frit Buchner, this synthesis is over a century year old (Marvel et al., 1923, Org. Synth.) and confirmed to be working by many independent chemists, including me.
Moreover, every publication in that journal should be peer reviewed, so it is one of the most trusted source for practical organic chemist.
Link for the original document - https://www.orgsyn.org/demo.aspx?prep=CV1P0347
If you fail, then you definitely doing something very wrong or your reagents are not what you expect it are.
Chloroform could be substituted by DCM, but anyway it is not necessary.
If you want good results better to use paraformaldehyde, not formaldehyde with methanol, the more MeOH the more colored RM in my experience.
Without methanol you not need to distill reaction mixture, just hold temperature below 100C, it works even at lover t, just take more time.
You absolutely need aspirator vacuum for distilling portions of water if you want nice white product.
The key for a good purity is fractional crystallizations, the more the better result.
I used 5-6 times, a little bit more than in the original procedure and got fantastic results.
So after 6+ hours of 100C, distill some water under vacuum, cool down, suction filter, and repeat.
First 2-3 fractions will be ammonium chloride. Then methylamine*hcl with crystal structure clearly different from first batches, more like hygroscopic shiny flakes.
The last mother liquor will contain mostly dimethylamine*hcl and should be discarded if don't need it.
The final step is multiply crystallization from hot abs. ethanol or methanol as described. But it also is not necessary for many synthesis, it just for removing last traces of water, NH3*HCl and Me2NH*HCl.
So as you can see it is time consuming, many days of working, but you can start with pretty large batch and prepare non-trackable pure Methylamine for month or years.
Moreover, every publication in that journal should be peer reviewed, so it is one of the most trusted source for practical organic chemist.
Link for the original document - https://www.orgsyn.org/demo.aspx?prep=CV1P0347
If you fail, then you definitely doing something very wrong or your reagents are not what you expect it are.
Chloroform could be substituted by DCM, but anyway it is not necessary.
If you want good results better to use paraformaldehyde, not formaldehyde with methanol, the more MeOH the more colored RM in my experience.
Without methanol you not need to distill reaction mixture, just hold temperature below 100C, it works even at lover t, just take more time.
You absolutely need aspirator vacuum for distilling portions of water if you want nice white product.
The key for a good purity is fractional crystallizations, the more the better result.
I used 5-6 times, a little bit more than in the original procedure and got fantastic results.
So after 6+ hours of 100C, distill some water under vacuum, cool down, suction filter, and repeat.
First 2-3 fractions will be ammonium chloride. Then methylamine*hcl with crystal structure clearly different from first batches, more like hygroscopic shiny flakes.
The last mother liquor will contain mostly dimethylamine*hcl and should be discarded if don't need it.
The final step is multiply crystallization from hot abs. ethanol or methanol as described. But it also is not necessary for many synthesis, it just for removing last traces of water, NH3*HCl and Me2NH*HCl.
So as you can see it is time consuming, many days of working, but you can start with pretty large batch and prepare non-trackable pure Methylamine for month or years.
I followed the original synth the first time and I the second time I followed one I was given by one of the experts here. I refluxed under vacuum for 4 hours and distilled under vacuum for 2 hours. The temps never Reached the target level though, perhaps my vacuum is stronger than they were using in 1910. That's what I assumed.The second time the methylamine hcl and the product I made with it looked exactly like everyone's pictures the methylamine hcl even produced flammable gas when neutralized with NaOH and water. But the product has no cns action.
I have here a liter of technical grade formaldehyde with 5%methanol and I'm going to try again but do I need to distill the methanol off to start? I'm going to read some more, it's true my ammonium chloride is fertilizer grade not technical grade could that be the problem? How do you decide when "a round" of reducing the volume of the rm is done? I was measuring it and stopping every time I halved the volume but only get 4 rounds that way and 4 batches of crystals. Would the methanol I use at the end not being dry enough cause it? I can't imagine that was the problem though because I distilled it twice and put in 100% w/w, 3a sieve for several days
I have here a liter of technical grade formaldehyde with 5%methanol and I'm going to try again but do I need to distill the methanol off to start? I'm going to read some more, it's true my ammonium chloride is fertilizer grade not technical grade could that be the problem? How do you decide when "a round" of reducing the volume of the rm is done? I was measuring it and stopping every time I halved the volume but only get 4 rounds that way and 4 batches of crystals. Would the methanol I use at the end not being dry enough cause it? I can't imagine that was the problem though because I distilled it twice and put in 100% w/w, 3a sieve for several days
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- By FENTAMAS
That effort do not worth it.
And that's just authors' speculation about vacuum, which itself likely cannot influence selectivity, as is with formic acid excess too.
Maybe it is just effect of reduced temperature, more effective stirring of RM by bubbling and more full conversion of NH3*HCl, etc.
Later authors don't use vacuum reflux, moreover it is quite uncommon method even nowadays.
Reduced boiling temperature also will be in the case of excess of MeOH in formalin, because of esterification of formic acid and forming low boiling methyl formate and other by-products, but as I already noted, try to avoid it.
And that's just authors' speculation about vacuum, which itself likely cannot influence selectivity, as is with formic acid excess too.
Maybe it is just effect of reduced temperature, more effective stirring of RM by bubbling and more full conversion of NH3*HCl, etc.
Later authors don't use vacuum reflux, moreover it is quite uncommon method even nowadays.
Reduced boiling temperature also will be in the case of excess of MeOH in formalin, because of esterification of formic acid and forming low boiling methyl formate and other by-products, but as I already noted, try to avoid it.
That's a fair point. I'll have to read it again with that in mind (that the vacuum lowers the temperature and makes the stir bar turn easier, ect.) This document was linked to me by one of the site experts so I didn't scrutinize it heavily. Even if I decide it isn't proven that the vacuum itself is the reason they achieved a higher yield I might decide that the cause doesn't matter and the effect does. We consider gravity and magnetism effect and plan for it every day even though the mechanism is debatable. Buying formaldehyde is stressful because I'm not a taxidermist or farmer. I have more spare time than money or bravery to buy formaldehyde without a legitimate use. It's not free. I'll probably choose to maximize my yield over convenience. I'll have $33 in this formaldehyde whether I get a kg of methylammonium chloride or a gram from it. It can't be bought legally here and there is no end to the amount I can use
I feel like there is a reason, because using model airplane fuel to make methylamine in vitro is a common route.. either it degrades quickly or...it sounds like an energetic reaction