Aliphatic amine compounds are formed when one or more hydrogen atoms in ammonia (NH3) are replaced by one, two or three alkyl or alkanol radicals. The lower aliphatic amines are gases like ammonia and freely soluble in water, but the higher homologues are insoluble in water. All the aliphatic amines are basic in solution and form salts. The salts are odourless, non-volatile solids freely soluble in water.
According to the number of hydrogens substituted, the amines may be primary (NH2R), secondary (NHR2) or tertiary (NR3).
Aliphatic amines are found in the chemical, pharmaceutical, rubber, plastics, dye-stuff, textile, cosmetics and metal industries. These chemicals are used as intermediates, solvents, rubber accelerators, catalysts, emulsifiers, synthetic cutting fluids, corrosion inhibitors and flotation agents. Several are used in the manufacture of herbicides, pesticides and dyes. In the photography industry, triethylamine and methylamine are used as accelerators for developers. Diethylamine is a corrosion inhibitor in the metal industries and a solvent in the petroleum industry. In the tanning and leather industries, hexamethylenetetramine is used as a tanning preservative; methylamine, ethanolamine and diisopropanolamine are softening agents for hides and leather.
2-Dimethylaminoethanol functions as a control agent for the acidity of boiler water treatment. Triethanolamine, isopropanolamime, cyclohexylamine and dicyclohexylamine are used in dry-cleaning soaps. Triethanolamine is used extensively in industry for the manufacture of surface-active agents, waxes, polishes, herbicides and cutting oils. It is also used to recover hydrogen sulphide from sour natural gas and sour crude petroleum. Ethanolamine extracts both carbon dioxide and hydrogen sulphide from natural gas.
Ethylamine acts as a stabilizer for rubber latex and as a dye intermediate, while butylamine is a pesticide and a strong alkaline liquid used in the rubber, pharmaceutical and dye-stuff industries. Ethylenediamine is another strongly alkaline liquid used in the preparation of dyes, rubber accelerators, fungicides, synthetic waxes, pharmaceuticals, resins, insecticides and asphalt wetting agents. Dimethylamine and isobutanolamine find use in the rubber industry as vulcanization accelerators. Dimethylamine is also used in the tanning industry and in the manufacture of detergent soaps.
Ethylenimine is an important compound found in the paper, textile, petroleum, lacquer and varnish, cosmetics and photography industries. Diethanolamine is a scrubbing agent for gases, a chemical intermediate, and an emulsifier in agricultural chemicals, cosmetics and pharmaceuticals. Other widely used emulsifying agents include isobutanolamine, isopropanolamine and cyclohexylamine.
Since the amines are bases and may form strongly alkaline solutions, they can be damaging if splashed in the eye or if allowed to contaminate the skin. Otherwise they have no specific toxic properties, and the lower aliphatic amines are normal constituents of body tissues, so that they occur in a large number of foods, particularly fish, to which they impart a characteristic odour. One area of concern at present is the possibility that some aliphatic amines may react with nitrate or nitrite in vivo to form nitroso compounds, many of which are known to be potent carcinogens in animals, as is discussed more fully in the accompanying box.
Allylamine. The vapour is intensely irritating. In animals there is evidence of effects on the heart and circulatory system. Myocardial and vascular legions have been observed. Some of allylamine’s toxicity has been attributed to the formation of acrolein in vivo. There is also a definite risk of explosion over a wide range of concentrations in air.
Butylamine is the most important isomer commercially. Its vapour has been observed to have severe effects on the central nervous system (CNS) of animals exposed to it. It has intense effects on humans. It is extremely irritating to the eyes and respiratory tract. It also affects the CNS and can cause depression and even unconsciousness. Chest pains and severe coughing have also been reported. Butylamine is readily absorbed through the skin. Any absorbed butylamine is readily metabolized.
A main toxic effect of cyclohexylamine is to act as an irritant. It may damage and sensitize the skin. Cyclohexylamine is also a weak methaemoglobin inducer. This amine is also a principal metabolite of cyclamate.
Diethanolamine is irritating to the skin and mucous membranes. Exposure can lead to nausea and vomiting.
Dimethylamine vapours are both flammable and irritating. The solutions which it forms are strongly alkaline.
Ethanolamine may be weakly irritating but is not associated with major toxic effects on humans.
Ethylamine can cause eye irritation. Corneal damage may occur in those exposed to the vapour. The compound is excreted unchanged by humans.
Ethylenediamine damages the eyes, skin and respiratory tract. Sensitization may follow vapour exposure.
Methylamine a stronger base than ammonia, and the vapour is irritating to the eyes and respiratory tract. Cases of sensitization (bronchial) have been reported. The warning properties of this chemical are not good, since olfactory fatigue can set in.
Propylamine vapour may be injurious to the eyes and respiratory tract. Transitory visual disturbances have been reported.
Triethanolamine is of low human toxicity and is commonly added to many cosmetics and similar products.
Aliphatic amines tables
Table 1 - Chemical information.
Table 2 - Health hazards.
Table 3 - Physical and chemical hazards.
Table 4 - Physical and chemical properties.