Methylamine hydrochloride, separation

Methylamine Hydrochloride. 125 g of ammonium chloride and 250 g 40% aqueous formaldehyde solution are placed in a distilling apparatus, with the thermometer well below the surface of the liquid. The mixture is slowly heated to 104° and held at this temp until no more liquid distills. The product in the flask is cooled and filtered from ammonium chloride. The liquid is then evaporated on a water bath to half its original volume and a second crop of ammonium chloride is filtered off. The filtrate is concentrated at 10(T until a crystalline scum forms on the surface. On cooling methylamine hydrochloride separates and is removed by filtration. Further evaporation and cooling produces another crop of methylamine hydrochloride, which is also filtered. The combined yield is treated with boiling chloroform, filtering hot, washed with room temp chloroform, and dried in a vacuum desiccator. Yield 40 g. 

The chemist may have to do one, or possibly two more volume reductions before all of the excess ammonium chloride is removed (usually just one more). Now, what the chemist will be looking at after the last removal of ammonium chloride is a light yellow, slightly viscous solution that is about 1/3 the volume of the original filtrate. The chemist puts this to distill once more. What often happens next is that while the chemist goes off to watch TV the solution will distill off just a little bit of volume and poof the hot solution will become an instant mass of methylamine hydrochloride. If this doesn t happen for the chemist then she will just reduce a little bit and chill. Either way, what the chemist is going to have is a nice mass of methylamine hydrochloride crystals that she separates by vacuum filtration. 

The following cheap procedure serves for the preparation of large amounts of methylamine hydrochloride (Brochet and Gambier, Bull. Soc. chim., 1895 [iii.], 13, 533). Heat together in a distilling flask attached to a downward condenser 250 g. of ammonium chloride and 570 c.c. of 35 per cent formaldehyde solution. With the thermometer in the liquid, slowly raise the temperature to 104° and maintain at this point until distillation ceases (about 4-5 hours from the start). By then 100-120 g. of water and methyl alcohol will have collected in the receiver. Cool the flask, remove the ammonium chloride which separates by filtration at the pump, and evaporate the filtrate to half its volume on the water bath. Again remove ammonium chloride by filtration and concentrate the filtrate until a film of crystals forms on the surface. Cool and separate the methylamine hydrochloride by Ultra-... 

Methylcyclophosphazenes N3P3Me6 and N4P4Me8 are more conveniently prepared and separated using methylamine hydrochloride, rather than ammonium chloride, in the reaction with Me2PCl3.98 The initial product from this reaction is probably (Me2PClNMe)2, which on pyrolysis gives a mixture of N3P3Me6 MeCl and... 

Nitrosomethyl urea. 20 g of methylamine hydrochloride (see below for formula) and 30 g of potassium cyanate are dissolved in 120 cc of water, heated to 70° for 15 min and then to boiling for a few min more. Cool to 0° and add a solution (also cooled to 0°) of 20 g of sodium nitrite in 40 cc of water. 100 cc of 25% sulfuric acid is added, with stirring. The nitrosomethylurea separates, is filtered, washed with ice water, pressed, and dried under vacuo. Crystallize from methanol to get light yellow needles. 

Since ammonium chloride is not absolutely insoluble in 100 per cent ethyl alcohol (100 g. dissolve 0.6 g. at 150) the methylamine hydrochloride purified in the manner described contains appreciable traces of it. A purer product can be prepared by recrystallizing from -butyl alcohol, in which the solubility of ammonium chloride even at the boiling temperature is negligibly small. Methylamine hydrochloride is somewhat less soluble in this solvent than in ethyl alcohol, but as a rule three extractions carried out at 90-100° with 4-6 parts of fresh butyl alcohol for each extraction result in a substantially complete separation. Since the last traces of the solvent are not readily removed by exposure to air, a solution of the recrystallized material in a small quantity of water should be distilled until free of alcohol, and allowed to crystallize. 

After diluting the reaction liquid with acetone it is filtered, and the residue obtained after the evaporation of the filtrate in vacuo, and complete drying over pentoxide of phosphorus is then dissolved in absolute alcohol, and to this is added about the same volume of dry ether, until turbidity just commences to occur. After a short time the hydrochloride of the m-hydroxyphenylethanol-methylamine will separate out as a colorless mass of crystals at a melting point of 142°C to 143°C. 

After cooling, 96 grams of methylamine hydrochloride were separated after further concentration a second crop (18 grams) was obtained. The filtrate was now concentrated as far as possible at 100° and was left for twenty-four hours in a vacuum over sodium hydroxide, after which the semi-soft residue was digested with chloroform, when 20 grams of methylamine hydrochloride which had been washed with chloroform to remove the dimethylamine hydrochloride, were obtained. The total yield was 128 grams. Source Werner 1917... 

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