§ 654. Dimethylamine, (CH3)2NH.—Dimethylamine is also a gas; it has been found in various putrefying substances. It forms crystalline salts, such as the hydrochloride, the platinochloride (Pt = 39·1 per cent.), and an aurochloride (Au = 51·35 per cent.). It is not poisonous.
In Brieger’s process it may occur in both the mercuric chloride precipitate and filtrate. From cadaverine it may be separated by platinum chloride; cadaverine platinochloride is with difficulty soluble in cold water and crystallises from hot water, while dimethylamine remains in the mother liquor. From choline it may be separated by recrystallising the mercuric precipitate from hot water. From methylamine it may be separated by converting into chloride and extracting with chloroform; dimethylamine chloride is soluble, methylamine chloride insoluble in chloroform.
§ 655. Trimethylamine, (CH3)3N.—Trimethylamine in the free state is an alkaline liquid with a fishy odour, boiling at 9·3°; it is not toxic save in large doses.
It occurs in a great variety of plants, and is also found in putrefying substances. It is a product of the decomposition of choline, betaine, and neuridine, when these substances are distilled with potash.
In Brieger’s process, if an aqueous solution of mercuric chloride is used as the precipitant, trimethylamine (if present) will be almost entirely in the filtrate, from which it can be obtained by getting rid of the mercury by SH2, filtering, evaporating to dryness, extracting with alcohol, and precipitating the alcoholic solution with platinic chloride. It forms crystalline salts with hydrochloric acid, platinum chloride, and gold chloride; the platinum double salt yields 37 per cent. of platinum, the gold salt 49·4 per cent. gold. The gold salt is easily soluble, and this property permits its separation from choline, which forms a compound with gold chloride soluble with difficulty.
§ 656. Ethylamine, C2H5NH2.—Ethylamine is in the free state an ammoniacal liquid boiling at 18·7°. It is a strong base, miscible with water in every proportion. It has been found in putrefying yeast, in wheat flour, and in the distillation of beet sugar residues. It is not poisonous; the hydrochloride forms deliquescent plates melting at 76°-80°; the platinochloride contains 39·1 per cent. of platinum, and the gold salt 51·35 per cent. of gold. In other words, the same percentages as the corresponding salts of dimethylamine, with which, however, it cannot be confused.
§ 657. Diethylamine, (C2H5)2NH, is an inflammable liquid boiling at 57·5°; it forms salts with hydrochloric acid, platinum and gold, &c.; the gold salt contains 47·71 per cent. of gold, and its melting-point is about 165°.
§ 658. Triethylamine, (C2H5)3N, is an oily base but slightly soluble in water, and boiling at 89°-89·5°. It gives no precipitate with mercuric chloride in aqueous solution; it forms a platinochloride containing 31·8 per cent. of platinum. It has been found in putrid fish.
§ 659. Propylamine.—There are two propylamines; one, normal propylamine, CH3CH2.CH2.NH2, boiling at 47°-48°, and iso-propylamine, (CH3)2CH.NH2, boiling at 31·5°; both are ammoniacal fish-like smelling liquids. The hydrochloride of normal propylamine melts at 155°-158°, and iso-propylamine chloride melts at 139·5°.
It has been found in cultures of human fæces on gelatin. None of the above amines are sufficiently active in properties to be poisonous in the small quantities they are likely to be produced in decomposing foods.