Methylamine Freebase Solution Preparation

[G.Patton]

Introduction​

This post is written with a purpose to explain how to prepare methylamine freebase aqueous (cas 74-89-5) and methanol (cas 74-89-5) solution with known concentration from methylamine hydrochloride (cas 593-51-1) from. This issue is frequently met by customers around EU and other countries by reason that methylamine freebase is regulated by local rules. So that methylamine is bought in available and legal form of hydrochloride form.​

Methylamine hydrochloride​

Procedures​

All calculation are made for 1kg of the final solution.

Preparation of Methylamine 40% mass Water Solution​

1. Methylamine hydrochloride CAS 593-51-1 869g (12.88 mol), NaOH 514.5g (12.88 mol) and distilled water ~700g are weighted.
2. Distilled water ~700g is poured into 2L vessel, which can be tightly closed such as flat/round bottom flask with ground glass cap.
3. NaOH 514.5g is poured there and dissolved completely until transparent solution and ~50-60°C temperature (exothermic reaction).
4. Methylamine hydrochloride 869g is poured into alkali water solution in portions and the flask is closed immediately. Solution is stirred well until a complete dissolution and room temperature. NaCl precipitate is formed.
5. Silicone hose with flask connector is attached to the reaction flask with methylamine freebase.​

6. In a different 2L flask with 600g water a silicone hose is prepared to immersed into the water.
7. Heater is turned on, methylamine solution is simmered and methylamine gas is bubbled through second water solution. Important to say, that hose with methylamine has to be immersed into the water layer after heating about 50-60 °C to avoid a suck-back.

8. In about 15 min the heating of the first flask with NaCl can be stopped and the second water solution is weighted. It has to reach 1 kg.
9. If there is less than 1 kg of solution, continue to heat the first solution and bubble gas through the second one.​

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Note: This method is very approximate by reason methylamine gas is volatile and part of this gas will be lost. The second flask with the solution must be connected with the atmosphere. The best option is a reflux condenser on a second flask that reduces the loss of methylamine.

The methylamine ⩽40% water solution is ready to use.

Preparation of Methylamine 30% mass Methanol Solution
1. Methylamine hydrochloride CAS 593-51-1 652.2 g (9.66 mol), NaOH 385.9g (9.66 mol) and methanol 526.1g are weighted.
2. Methanol 526.1g is poured into 2L vessel, which can be tightly closed such as flat/round bottom flask with ground glass cap.
3. NaOH 385.9g is poured there and dissolved completely until transparent solution and room temperature (exothermic reaction).
4. Methylamine hydrochloride 652.2g is poured into alkali methanol solution in portions and the flask is closed immediately. Solution is stirred well until a complete dissolution and room temperature.
5. NaCl 564.5g is precipitated and has to be filtered (without vacuum).

The methylamine ~30% methanol solution with part of water is ready to use.​

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Note: Water can be removed with help of molecular sieves 3A. In this case, you should add 700g of methanol at the 2 stage to get ~30% solution.​

 

[rampage]

this is what ive been looking for thankyou g.patton, no doubt i'll have some questions

 

[Regis Kimble]

Any time one is dissolving a gas into a liquid, please note that solubility of a gas is far greater in a cold liquid than in one at room temperature.