METHYLAMINE in water

The solutions of all the methylamines in water are alkaline, but the alkalinity decreases with the number of methyl groups. 

Solutions of methylamine in water are obtainable from Eastman Kodak Company (33 per cent) and Rohm and Haas Company (35 per cent). 

The methylamine generator consists of a i-l. flask fitted with a dropping funnel and outlet tube, which in turn is connected to a 25-cm. drying tower containing soda-lime, followed by a i-l. safety trap (Note 1). In the flask is placed 200 g. of technical sodium hydroxide flakes, and 263 g. of a 33-35 per cent solution of methylamine in water (Note 2) is dropped in slowly at such a rate that an even current of gas is evolved. When the addition has been completed and the gas bubbles very slowly into the... 

The above described methodology was found to be very useful in a solid-supported synthesis of pyrazoles and pyrimidines via propenones developed by Westman and co-workers35 (Scheme 5.19). Merrifield resin was reacted with methylamine in water at 150°C for 10 min to form the solid-supported benzylmethylamine (3) in high yield (86% yield, 1.08 mmol/g based on elemental analysis). After washing, the resin was treated with 5 equiv. DMFDEA and 5 equiv of 4-phenoxyacetophenone at 180°C for 10 min in DMF to form the solid supported benzyl methyl aminopropenones (4). 

CH3NH2 (aq.). Data on the heat of solution of gaseous methylamine in water were obtained by Bonnifoi3 and Felsing and Wohlford.1... 

Base ionization constants You won t be surprised to leam that like weak acids, weak bases also form equihbrium mixtures of molecules and ions in aqueous soluhon. Therefore, the equilibrium constant provides a measure of the extent of the base s ionization. The equilibrium constant for the ionization of methylamine in water is defined by this equilibrium constant expression. 

To do the reaction, 300 ml of phenylacetone is put into the bottle, followed by 300 ml of 40% methylamine in water. The two of them react immediately to convert a good portion of the mixture into the intermediate Schiff s base. The mixture gets warm, and some methylamine gas fumes off. 

He is now ready to run the reaction. If he has methylamine gas in a cylinder, he puts 1 liter of 95% ethyl alcohol (190 proof grain alcohol) in the bomb. If he has 40% methylamine in water, he uses 1 liter of absolute ethyl alcohol. Then he adds the same amount of methylamine as used in the first method described in this chapter. If he used methylamine gas from a cylinder, he adds 100 ml each of ether and benzene to the bomb. Then he adds 90 grams of Raney nickel catalyst and 25 grams of sodium acetate. Finally, he adds 300 ml of phenylacetone to the bomb. 

Then the chemist adds an equal volume of water to the liquid methylamine, about 220 ml. He has just made about 450 ml of 40% methylamine in water. The water allows him to keep it at room temperature. He pours it into a champagne bottle and tightly stoppers it. This methylamine can be used to make N-methlyformamide, but cannot be used in the hydrogenation... 

Samples of 40% methylamine in water, urea, thiourea, DTT and CHAPS were obtained from Sigma-Aldrich (Milwaukee, WI). HEPES was obtained from Fisher Scientific (Pittsburgh, PA). 

The pyrrolizinimine (68), reacted with methyl iodide or with methylamine in water to give pyrroles (69) and (70) <74LA2ll0>. 

Dissolving methylamine in water causes the establishment of a similar equilibrium. H H... 

Proton transfer with solvent participation always competes with direct bimolecular proton transfer, at least in principle, and comparison of the two rates is of theoretical interest. Unfortunately, data are available only in rare instances. The most complete series is that for the methylamines in water second-order rate constants for reaction with (equation 3) and without (equation 4) water participation are compared in Table 3 (p. Ill)... 

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