Methylamine.hydrochloride

Caution.—If the ethanol used to extract the methylamine hydrochloride is not absolute, i.e., if it contains traces of water, considerably less than the above suggested quantity will be required for the extraction, because the solubility of the hydrochloride will be markedly increased by the water present. The recrystallised material will now, however, contain traces of ammonium chloride. 

The best method of drying the precipitate of methylamine hydrochloride is by centrifuging the Compound is hygroscopic. 

The absence of ammonium chloride and methylamine hydrochloride may be shown by the complete solubility of the product in chloroform. 

An alternative method of preparation involves the interaction of methylamine hydrochloride with urea to give methylurea, followed by interaction with nitrous acid as above ... 

Salts. Sodium benzoate Sodium benzenesulphonate Aniline hydrochloride Methylamine hydrochloride. 

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 way the chemist knows that she has methylamine and not ammonium chloride is that she compares the look of the two types of crystals. Ammonium chloride crystals that come from this reaction are white, tiny and fuzzy. The methylamine hydrochloride crystals are longer, more crystalline in nature and are a lot more sparkly. The chemist leaves the methylamine crystals in the Buchner funnel of the vacuum filtration apparatus and returns the filtrate to the distillation set up so it can be reduced one last time to afford a second crop. The combined methylamine hydrochloride filter cake is washed with a little chloroform, scraped into a beaker of hot ethanol and chilled. The methylamine hydrochloride that recrystallizes in the cold ethanol is vacuum filtered to afford clean, happy product (yield=50%). 

Transfer the filtrate to a ceramic evaporating dish and heat on a water bath until a crystalline scum forms on the top. Cool the dish quickly then filter the mess on the vacuum Buchner to yield 96g of Methylamine Hydrochloride. Concentrate the filtrate once again to obtain a second crop of crystals, -IQg. Concentrate the filtrate a third time as far as possible using the water bath, then store the dish in a vacuum dessicator loaded with Sodium Hydroxide in the bottom for 24 hours. Add Chloroform to the residue left in the crucible to dissolve out Dimethylamine Hydrochloride (distill off the Chloroform to recover - good stuff) then filter on the venerable old vacuum Buchner funnel to yield an additional 20g of Methylamine Hydrochloride, washing the crystals in the funnel with a small poiiion of Chloroform ( 10mL). 

Footnote 4 - The solubility of Ammonium Chloride in absolute Ethanol is 0.6g/100g at 15C. The solubility in n-Butyl Alcohol is neglible, even at its boiling point. If you use n-Butyl Alcohol, you will only need to perform 3 reflux/filter operations to obtain sufficiently pure Methylamine Hydrochloride. 

Methylamine hydrochloride [593-51-1] M 67.5, m 231.8-233.4°, h 225-230°/15mm, pK 10.62. Crystd from n-butanol, absolute EtOH or MeOH/CHCls. Washed with CHCI3 to remove traces of dimethylamine hydrochloride. Dried under vacuum first with H2SO4 then P2O5. Deliquescent, stored in a desiccator over P2O5. 

Mannich has prepared arecaidine aldehyde (IV) by allowing a mixture of formaldehyde, acetaldehyde and methylamine hydrochloride to stand at 70° and pK 3. Some dialdehyde, MeN(CH2. CHa. CHO)2, is formed and this by loss of water produces arecaidine aldehyde. The latter is, converted into arecoline by the VVohl and Johnson process described above. 

Schopf and Lehmann found that lobelanine could be synthesised by keeping at 25° a mixture of glutardialdehyde, methylamine hydrochloride and benzoylacetic acid in a buffered solution. The best yield was obtained at pH 4-5, and appeared to be complete in forty hours. At pH 7 or 9, 11 or 13, the yield was very small. This synthesis under physiological conditions is represented as occurring in accordance with the following scheme —... 

Using maleic aldehyde, acetonedicarboxylic acid and methylamine hydrochloride in aqueous solution, in presence of sodium acetate, Iheobrazhenskii, Rubtsov, Dankova and Pavlov have prepared troperume. 

Teloidine, the basic hydrolytic product of meteloidine, has been synthesised recently under physiological conditions by Schdpf and Arnold, on the lines of the tropinone synthesis, mesotartaric aldehyde (CHOH. CHO)j, being condensed at 25° with aeetonediearboxylic acid bnd methylamine hydrochloride to teloidinone (5-keto-l 2-dihydroxy-tropane) whieh on eatalytic hydrogenation yielded teloidine (1 2 5-trihydroxytropane). 

Methylamine Hydrochloride.- -This reaction, which yields the ])riiviary amine, is appheahie, not only to thealijihatic, hill, dsci Ic) tlieaiomatic. innclcs. The lonnation ofanthianilicacid from ]jhth diinidc is a process of technical importance. 13y the... 

Both PS-A and PS-B have a tendency to hydrate like panal, and they also form adducts with methylamine. The adducts, PS-A/MA and PS-B/MA, are prepared by incubating PS-A or PS-B in 75 % methanol containing an excess amount of methylamine hydrochloride plus some sodium acetate to neutralize the HC1, at 45°C for 30 min. The adducts can be purified by HPLC on a PRP-1 column (80% acetonitrile containing 0.05% acetic acid). Their chemical structures have been determined by NMR and mass spectrometry as shown in Fig. 9.8 (p. 288). Both adducts are colorless and show an absorption maximum at 218 nm. 

Iminium ions bearing an electron-withdrawing group bonded to the sp carbon of the iminium function are very reactive dienophiles. Thus, iminium ions 26 generated from phenylglyoxal (Scheme 6.15, R = Ph) or pyruvic aldehyde (R = Me) with methylamine hydrochloride, react with cyclopenta-diene in water at room temperature with good diastereoselectivity [25] (Scheme 6.15). If glyoxylic acid is used, the formation of iminium salt requires the free amine rather than the amine hydrochloride. 

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