Page:The New International Encyclopædia 1st ed. v. 01.djvu/550

AMINES. hydroxide, according to the following equation:

(C,H,).NI + AgOH = (CHJ.NOH + Agl Tetr-ethyl-am- monium iodide Tetr-ethyl-am- moDiuni hydroxide just as ammonium iodide is transformed into ammonium hydroxide: H,N1 + AgOH = H.NOH + Agl Ammonium iodide Ammonium hydroxide

Bases like (C^HsJ.NOH, derived from ammonium hydroxide by substituting hydrocarbon radicles like methyl (CH3), ethyl (CJh^), 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 C.,H„X: is it the primary amine CjHjNHj (propyl-amine), or the tertiary amine (CHjjjN (tri-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 CjH,_,XI, proves that the substance C3H0N, found in herring-brine, is a tertiary amine (CHjjjN, for only one methyl group (CH^) is required to transform it into the substituted ammonium iodide C,H„NI [(CHs)4NI] ; while if it were the primary amine, C,H-NII,, the number of methyl- groups taken up would be three, and the com- pound C'eH^NI [C,H,(CH:,),NI] 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 subclasses of amines being characterized as follows:

1. Primary amines are converted by nitrous acid into the corresponding alcohols; thus, ethyl-amine is transformed into ethyl alcohol, according to the following chemical equation:

C.H,NH, + HNO, = CJI5OH + H,0 + N^

just as ammonia is transformed into water:

NHj + HXO, — H,0 + H,0 + N, Ammonia Nitrous Water acid

2. Secondary amines are converted by nitrous acid into compounds containing the group NO, and called nitroso-amines: thus, di-ethyl-amine, (C»H3),XH, is transformed into ethyl-nitroso- amine, according to the following equation:

(C3H=)2NH + HNO, = (aH,.),N. NO + H,0 Di-ethyl- aminc Ethyl-nitrogo- "aminc

3. Tertiary amines are not affected by nitrous acid.

It has been stated above that when ethyl-iodide or similar substances are treated with anunonia, four reactions take place simultaneously, and a mixture of four compounds is obtained: viz., the salts of a primary, a, secondary, and a tertiary amine, and a substituted ammonium iodide. The separation of the four compounds may be effected by the following method: (1) The mixture is

distilled with caustic potash, which leaves the substituted ammonium iodide undecomposed as a residue, while the salts of the three amines are decomposed, and a mixture of the amines in the free state passes over in the distillate. (2) When the distillate is treated with ethyl-oxalate, the primary amine (say, ethyl-amine) is converted into a derivative of oxamide (the amide of oxalic

CONH2 acid, I, according to the following equation: conrJ

COOC.H, CONHCjH, C,H,NH,-f I =1 +2C,H,0H; COOCHs CONHC,H, Ethyl-amine Ethyl-oxalate Ethyl-oxamide Alcohol

while the secondary amine (say, di-ethyl-amine) is converted into a derivative of oxamic acid

CONH, (the amide of oxalic acid, I, according to Ethyl-amine Nitrous acid Ethyl alcohol

' COOH j' the following equation: COOCjH, CON(C,H,), ( C:H5 ) ,NH + 1 =1 + C^H^OH ; COOC,H, COOC.H5 Di-ethyl- Ethyl- Ethyl-di-ethyl- Alcohol amine oxalate osaraate

the tertiary amine is not affected by treatment with ethyl-oxalate, and as it is much more vola- tile than both ethyl-oxamide and ethyl-di-ethyl- oxamate, it may be readily separated from these compounds by distillation. Finally, the two compounds derived respectively from the primary and secondary amines may be readily separated, since ethyl-oxamide is solid, while ethyl-di-ethyl- oxamate remains liquid on cooling the mixture. The primary and the secondary amines may be obtained separately in the free state by distilling the substances tints separated with caustic pot- ash, the reactions taking place, respectively, ac- cording to the following two equations:

CONHCH, + 2K0H = 2CjH,NHj + K.CJO, co> ONHC.H, Ethyl- oxamide CON (an,) J Ethyl- Potassium amine oxalate COOC.Hs Ethyl-di-cthyl- oxamate + 2K0H = (aHJ^NH + K.CA + C,H,OH Di-ethyl- Potassium Alcohol amine oxalate

The amines are much more powerful bases than ammonia. Their odor resembles that of ammonia, from which, however, the gaseous amines may be readily distinguished by their inflammability. Many liquid and solid amines, too, have been obtained. All of the amines known have been made by artificial chemical processes, and certain amines are found among the products of decomposition of nitrogenous substances. The quaternary ammonium bases (such as tetr-ethyl-ammonium-hydroxide) are similar, and even more powerful in their action than caustic potash.

Amines containing a benzene-nucleus are classed with the so-called aromatic compounds of organic chemistry, and are subdivided into amido-com- pounds and aromatic amines proper, according as their nitrogen is linked to the nucleus imme- diately, or through the medium of CH..-ffroups. Ordinary aniline is an example of an