Methylamine HCL usage?

[ACAB]

Hello,
my first post, of many questions I have, I hope you can help me.
In various recipes is often the talk of 40% methylamine alcohol solution. But I have now only Methylamine HCL, with which procedure do I make the solution?

As far as I know you can release the gas Methylamine by adding caustic soda. Does this produce any minor components?

I was thinking of stirring the methylamine HCL in ice-cold methanol and then adding NAOH. Would this work?

In a description, please also give the quantities, so that I can calculate it.

Thank you very much.

 

[halohydrin]

If you use reaction mixture directly, it'll contain other unreacted reactants and NaCl which will lower the solubility of methylamine. I recommend using gas generator to dissolve MeNH2 gas to other solvent. Using methanol as reaction solvent is fine, but you can use water too. I'd say it's better to use slight molar excess of base to get all methylamine salt reacted. Like 67.52 g Methylamine HCl (1 mole) with 45g NaOH (almost 1.2 molar equivalent). As methylamine gas, you won't get quantitive yield since some of the methylamine produced will dissolve in reaction solvent as soon as it's formed.

 

[Marvin "Popcorn" Sutton]

In some reactions, it is allowed to use Methylamine HCl with aqueous NaOH solution for methylamination instead of Methylamine gas. For example, the reaction of bromoketone in benzene with Methylamine HCl and a 30% aqueous solution of NaOH.

 

[ACAB]

If you use reaction mixture directly, it'll contain other unreacted reactants and NaCl which will lower the solubility of methylamine. I recommend using gas generator to dissolve MeNH2 gas to other solvent. Using methanol as reaction solvent is fine, but you can use water too. I'd say it's better to use slight molar excess of base to get all methylamine salt reacted. Like 67.52 g Methylamine HCl (1 mole) with 45g NaOH (almost 1.2 molar equivalent). As methylamine gas, you won't get quantitive yield since some of the methylamine produced will dissolve in reaction solvent as soon as it's formed.

halohydrinUnfortunately, I do not own a "Kipp" generator, I think that is what you meant. I would also find it difficult to produce the right amount of gas with it. The goal was to produce a 40% methylamine alcohol solution. How do I have to proceed?

My idea would be:
If I cool 77.65g methanol or ethanol far below -6°C, dissolve the 67.52g methylamine HCL in it and add 45g NaOH while stirring, the methylamine gas should be liquefied, have a mass of 31.06g and go into solution with the alcohol. This produces 58.44g NaCl and 18.08g water. Most of the salt could be filtered out if the solution does not get much warmer. Water would not be optimal, but could be removed later. So, at least theoretically, I would have a 40% methylamine alcohol solution plus the water and some salt.

I am open to any solution suggestion.

 

[ACAB]

In some reactions it is allowed to use Methylamine HCl with aqueous NaOH solution for methylamination instead of Methylamine gas. For example the reaction of bromoketone in benzene with Methylamine HCl and a 30% aqueous solution of NaOH.

Marvin "Popcorn" SuttonSo there is no procedure by which I can get methylamine HCL into an alcoholic solution? I am supposed to use an alcoholic methylamine solution.
The wording in the recipe reads:
"1 mol benzaldehyde, 1.2 mol nitroethane and 15 mL diluted aqueous methylamine in 150 mL alcohol."

Is it possible to do this with methylamine HCL or not? And when yes, how?

 

[Marvin "Popcorn" Sutton]

Is this the way you want to synthesize P2PN? I would recommend using a simpler method of synthesizing P2PN.

 

[ACAB]

Both recipes read equally simple, methylamine is just a different catalyst for the synthesis.
n-Butylamine is harder to get around here, I am looking for an alternative method.

 

[halohydrin]

As Marvin mentioned, you can use other Lewis bases besides MeNH2. Base acts as a catalyst(check Henry reaction) and catalytic amount is used in reaction. So your method may work, even if the solution is not exactly 40%, but reaction rate can vary. If you prepare solution that way, lots of extra gaseous methylamine will form - 1 mole reaction and about 22L MeNH2 in gas phase. So personally I think it's better to make more solution out of it, maybe even storing it in liquid form.

 

[ACAB]

It was about an alcoholic methylamine solution, the 40% I once saw that it is sold so. I thought there might be a process how to make such solutions with the methyamine HCL quite simply. I have found nothing to this, and have then thought up this procedure. I thought that it will be a lot of gas, for this reason deeper than -6°C, then the gas should still be liquid. But it can also be that the reaction does not start, because it is too cold. What happens when the solution gets warm, does the methylamine stay in solution or does it outgas? I would have to try everything out to find the right answers.
Thanks to you for now!

 

[halohydrin]

Outgassing will happen unless the bath temperature isn't kept way below it's bp. Methylamine is pretty volatile and evaporates easily. I can't find solubility data and enthalpy charts, so not sure about reaction spontaneity. Maybe trial and error is the answer.

 

[Marvin "Popcorn" Sutton]

Both recipes read equally simple, methylamine is just a different catalyst for the synthesis.
n-Butylamine is harder to get around here, I am looking for an alternative method.

PennywiseIt is usually easier to buy n-butylamine than to gas alcohol with methylamine yourself. Methylamine HCl is a precursor in many places.
To obtain a solution of methylamine in alcohol, a round-bottom flask with a dropping funnel and an outlet into a Drexel flask is used. Solid sodium hydroxide is placed in the flask and a 50% solution of methylamine hydrochloride is added from the dropping funnel. This is how the methylamine enters the Drexel vial with the suspended alcohol. The amount of methylamine absorbed is determined by the weight.
Write us about the result. Good luck!

 

[ACAB]

It is usually easier to buy n-butylamine than to gas alcohol with methylamine yourself. Methylamine HCl is a precursor in many places.
To obtain a solution of methylamine in alcohol, a round-bottom flask with a dropping funnel and an outlet into a Drexel flask is used. Solid sodium hydroxide is placed in the flask and a 50% solution of methylamine hydrochloride is added from the dropping funnel. This is how the methylamine enters the Drexel vial with the suspended alcohol. The amount of methylamine absorbed is determined by the weight.
Write us about the result. Good luck!

Marvin "Popcorn" SuttonA setup I understand but don't know if I can master, methylamine is not harmless according to the safety data sheet.
Also I have to revise my statement, it was a 40% methylamine water solution that you find in stores, not an alcohol solution, sorry for that. The metylamine alcohol solution is made with an aqueous methylamine solution.
I now assume that water is in the gas wash bottle according to Drechsler and the methylamine HCL solution in the funnel contains 50% water.
My question about the setup: Should I connect a vacuum trap filled with water after the gas wash bottle to filter excess gas, or is the absorption in the gas wash bottle so good that no gas can escape?
Finally, I can still suck the apparatus empty with water jet pump, so the escaping gas quantity should be reduced to a minimum.
A vacuum trap I would have there, a gas wash bottle I would still have to get, but I have already contacted the dealer of my confidence.
Put the gas wash bottle on a scale, that would then show me when I have reached the 40%.
Would I be well positioned in this way to carry out this experiment?

 

[chinacat]

Does you synth require ahydrous conditions? if not you can dissolve methylamine hcl in water then add a solution of Naoh and add to rxn. When you freebase methylamine in water it warms up, it stinks.

 

[ACAB]

Does you synth require ahydrous conditions? if not you can dissolve methylamine hcl in water then add a solution of Naoh and add to rxn. When you freebase methylamine in water it warms up, it stinks.

chinacat
When methylamine is released, with NAOH and methylamine HCL, water is always formed, so this cannot be prevented for the time being. According to the recipe, however, an aqueous methylamine solution with alcohol is used, apparently this does not matter for the synthesis. Although I find in the recipe with n-butylamine as catalyst, the note that water interferes with the reaction and that the also arising water is taken out by dean-stark trap between reflux condenser and reaction vessel. By the amount of the separated water one recognizes probably also the end of the reaction.
Another recipe with n-butylamine is only heated under reflux for hours without water being separated.
Thus, I can't tell if that was just omitted or if water really interferes with the reaction.

If it can be prevented, I don't want to smell any methylamine at all, that can probably cause burns of the respiratory tract, I don't really want to do that.
The way about the gas wash flat as it has suggested Marvin "Popcorn" Sutton, to get methylamine in aqueous solution, but sounded very good, I think I will try so.