AMINES ( Derived from ammonia). A gen eral term applied in organic chemistry to an im portant class of basic compounds derived by sub stituting hydro-carbon radieles like methyl (CH,), ethyl (C,H,), etc., for one or more of the hydrogen atoms of muninonia The com pound CH NH, is called methyl-amine; the com pound (0}1,),NII — di-methyl-amine; the com pound — tri-methyl-amine. An amine derived by replacing one hydrogen atom of am inonia is called a prima ry amine; one derived by replacing two hydrogens is called a secondary amine; finally, one derived by replacing all of the hydrogen of ammonia is called a tertiary a miac. The three •olnp011llde just numtioned are exam ples, respectively, of primary, secondary, and tertiary amines.
The amines may be readily prepared by the action of halogen substitutive products of the hydrocarbons upon ammonia (Ilofmann•s method). Thus, by the action of mono-iodo ethane (ethyl iodide) upon ammonia. one or more ethyl groups (C,II,) are introduced into the molecule of ammonia (N11,), according to the following chemical equations, which usually take place sinmilaneously: 1. = + HI Ethyl- Ammonia Ethyl-amine Tlydriodic iodide acid 2. = + 2111 Di-ethyl-amine 3. = (C2115)3N + 3111 As the amines are powerful bases, they combine, of course, with the hydriodie acid formed in these reactions, producing salts like from which the amines are readily isolated by distilling with caustic alkalies.
Simultaneously with the above three reactions, a fourth reaction takes place: viz., between the halogen substitution product of the hydrocarbon and the tertiary amine produced in the third reaction. This fourth reaction, in the case of tri-ethyl-amine, is represented by the following equation: 4. C,11.1 = Ethyl-iodide Tri-ethyl-amine 'minium iodide The compound formed in this reaetion is evi dently ammonium iodide all the hydro gen of which has been replaced by ethyl-groups ; it is therefore named tetr-ethyl-ammo nium-iodide. When treated in aqueous solution
with silver hydroxide, it is transformed into tetr ethyl-ammonium hydroxide, according to the fol lowing equation: ,NI AgOH = AgI Tetr-ethyl-am- Tetr-ethyl-am- • monium iodide monium hydroxide just as ammonium iodide is transformed into ammonium hydroxide: AgOH = 11,NOH AgI Ammonium Ammonium iodide hydroxide Bases like derived from ammonium hydroxide by substituting hydrocarbon radicles like methyl (CH,), ethyl etc., for all of its hydrogen, are termed quaternary ammonium bases.
The above method of preparation of the amines and the substituted ammonium salts may also serve in determining the nature of an amine. An example will render this clear: an amine found in herring-brine has the molecular for mula is it the primary amine C,II,N112 (propyl-amine), or the tertiary amine OH-methyl-amine) ? To answer this question the amine may be treated with methyl iodide, and, when the reaction is completed, the result ing substance analyzed. The formation, as a final product of the reaction of the compound proves that the substance CAN. found in herring-brine, is a tertiary amine for only one methyl group (CH,) is required to transform it into the substituted ammonium iodide [ while if it were the primary amine, the number of methyl groups taken up would he three, and the com pound C,H„N1 would be formed. The number of groups, like methyl, ethyl, etc., taken up by an amine thus generally determines its nature.
The nature of amines is also shown by their behavior toward nitrous acid, the three sub classes of amines being characterized as follows: I. Primary amines are converted by nitrous acid into the corresponding alcohols; thus, ethyl amine is transformed into ethyl alcohol, accord ing to the following chemical equation: