COMPOUNDS CONTAINING NITROGEN. 543 



reaction is analogous to the decomposition of ammonium nitrite by heat, thus : 

 NH 4 ONO == HOH + H 2 + 2N. 



Aromatic amines behave differently toward nitrous acid, as will be shown 

 later. 



Another characteristic reaction which, as in the previous case, distinguishes 

 primary from the other amines, is that with chloroform and alkalies, giving rise 

 to the formation of iso-nitriles, substances having a most disagreeable odor. 

 (See tests for chloroform.) The reaction is this : 



C 2 H 5 NH 2 + CHC1.3 = C 2 H 5 NC + 3HC1. 

 Ethyl amine. Chloroform. Ethyl isonitrile. 



Poly-amines. Whenever two or more ammonia molecules are 

 linked together by hydrocarbon radicals, this is indicated by desig- 

 nating them as diamines, triamines, etc. 



Diethylene diamine (O 2 H 4 ) 2 (NH) 2 , (Piper azine), is a white, crystalline 

 substance, used medicinally on account of its solvent action on uric acid. 



Hexamethylenamine, Hexamethylenamina, (CH 2 ) 6 N 4 = 139.18 

 (Hexamdhylene tetramine, Urotropin). This compound results from 

 the action of ammonia on formaldehyde : 



6CH 2 + 4NH 3 = (CH 2 ) 6 N A -f- 6H 2 O. 



It is due to this reaction that ammonia is used to remove the 

 odor of formaldehyde after its use as a disinfectant. The compound 

 forms colorless, odorless crystals, which are soluble in 1.5 parts of 

 water; this solution has an alkaline reaction on red litmus. On 

 heating it sublimes with partial decomposition. When heated with 

 diluted sulphuric acid, it is decomposed into formaldehyde and 

 ammonia. 



This substance is sold under various trade names, such as cystogen, amino- 

 form, formin, uritone, urotropin. These are all identical with the official 

 hexamethylenamine. 



Some derivatives of hexamethylenamine have been introduced under 

 special names, such as salicylate (saliform), bromethylate (bromalin, bromo- 

 formin), tannate (tannopin or tannon), iodoform (iodoformin). 



Amides are substances derived from ammonia by replacement of 

 hydrogen atoms by acid radicals. Thus : 



Ammonia. Acetamide. Diacetamide. Carbamide or urea. 



Amides also resemble ammonia in their chemical properties ; to a 



