AMINE (am'in; from ammonia -I- Mr), a general name for a compound derived from ammonia by substituting one or more of its hydrogen atoms with an equivalent number of metallic atoms or basic organic radicals (Com pare AmmE). The reactions of the amines de pend upon the class to which the substituted alkyl belongs — whether (1) all aliphatic; (2) part aliphatic and part aromatic — with the ni trogen ring attached to the aliphatic residue (as benzylamine) ; (3) part aromatic and part aliphatic with the nitrogen attached to a carbco atom of the benzene ring (as methylaniline): and (4) pure aromatic amines (as aniline, diphenylamine, etc.). Group (1) is known as the aliphatic amines; (2) as the aromatic amines; (3) and (4) as the aromatic amino compounds. As in the case of the amide4 given monovalent radical can form three •nripounds of this sort according as it :places one, two or three of the hydrogen oms_ of the original ammonia. For example, 1.znonovalent basic radical "ethyl," arms primary ethyl amine (or lethylamine) when it replaces one atom of H in ; secondary ethyl amine (or Miethyla nine)), (C2H.)..NH, when it replaces two toms of H; and tertiary ethyl amine (or triethylamine), (C2I-13),.N, when it replaces 11 three of the hydrogen atoms in the ammonia. ['he base by which the hydrogen in the am nonia is replaced need not be organic. Po assium, for example, may replace an atom of t, with the formation of potassium monamine (or epotassamines), K.NH,. A derivative of ammonia, in which one atom of the typical hydrogen is replaced by a monovalent acid rad ical, and another by a monovalent basic radical or by a monad metal, may be considered to be either an amine or an amide. Thus CHa.C21-1.0. NH, in which one atom of the hydrogen has been replaced by the basic radical °methyl° (CH,) , and another by the acid radical °acetyl° 11 (C230), may be described as a modified methylamine, or as a modified acetamide. The amines are found in nature chiefly in the vege table alkaloids. They occur also in the blood
of some animals and generally among the de composition products of both animal and vege table organisms and also in decomposed min erals which have their origin in organic matter.
There are several methods by which amines may be prepared: (1) By the action of am monia or its alkyl derivatives on substitution products of the hydrocarbons; (2) by the re duction of nitrogen-containing substances ; (3) by the action of bromine and potash on the amides; (4) by the action of alkalies on alkyl isocyanates; (5) by hydrolysis of the alkyl esters of thiocarbamines and isocyanides with concentrated acids; (6) from compounds which certain substances form with alkyl halides; (7) by distillation of amino-acids with baryta. In addition, aliphatic primary and secondary amines may be obtained by the action of potash on the p-nitroso derivatives of secondary and tertiary aromatic amino-compounds, and ter tiary amines may be secured by heating primary and secondary bases with an excess of potas sium alkyl sulphate. Secondary and tertiary aromatic amino-compounds (dimethylaniline, etc.) are prepared on a large scale by heating the primary amines under pressure with al cohol and hydrochloric or sulphuric acid, at a temperature of from 360° to 400° F.
When ammonia is added to a cold solution of a salt of an amine, the amine is expelled from its combination and precipitated.
The amines of the aliphatic series are gen erally inflammable gases, or volatile liquids with a low boiling point and a density about 75 per cent that of water. They have a fishy odor, decidedly alkaline, and are freely soluble in water. Some of the highest members of this class are odorless solids, becoming car bonates upon exposure to moist air. The aro matic amines (benzylamine, etc.) are com paratively few ; they resemble generally the aliphatic amines, but are not so strongly basic.
The most important amines, in the arts, are methylamine, and aniline (q.v.).