382 CONSIDERATION OF CARBON COMPOUNDS. 



49. BENZENE DEEIVATIVES CONTAINING NITROGEN. 



Aniline, Phenyl-amine, C 6 H 5 NH 2 . The constitution of amines, 

 to which class aniline belongs, has been considered in Chapter 47. 

 Aniline is found in coal-tar and in bone-oil; it is manufactured on 

 a large scale by the action of nascent hydrogen upon nitro-benzene, 

 iron and hydrochloric acid being generally used for generating the 

 hydrogen. 



Experiment 59. Dissolve 20 c.c. of nitre-benzene (this may be obtained 

 according to the directions given in Experiment 57, using larger quantities of 

 the material) in alcoholic ammonia and pass through this solution hydrogen 

 sulphide as long as a precipitate of sulphur is produced ; the reaction takes 

 place thus : 



C 6 H 5 N0 2 + 3H 2 S = C 6 H 5 NH 2 + 2H 2 O + 88. 



Evaporate on a water-bath to expel ammonium sulphide and alcohol ; add to 

 the residue dilute hydrochloric acid, which dissolves the aniline, but leaves any 

 unchanged nitro-benzene undissolved. Separate the nitro-benzene from the 

 aniline chloride solution, evaporate this to dryness, mix with some lime, in 

 order to liberate the aniline, which may be obtained by distillation from a dry 

 flask. 



Pure aniline is a colorless, slightly alkaline liquid, having a pecu- 

 liar, aromatic odor, a bitter taste, and strongly poisonous properties. 

 It boils at 184.5 C. (364 F.). Like all true amines, it combines 

 with acids to form well-defined salts. 



Aniline dyes. The crude benzene used in the manufacture of aniline 

 dyes is generally a mixture of benzene, C 6 H 6 , and toluene, C 7 H 8 . 

 This mixture is first converted into nitro-benzene, C 6 H 5 NO 2 , and 

 nitro-toluene, C 7 H 7 NO 2 , and then into aniline, C 6 H 5 NH 2 , and tolu- 

 idine, C 7 H 7 NH 2 . When these substances are treated with oxidizing 

 agents, such as arsenous and arsenic oxides, hypochlorites, chromic 

 or nitric acid, etc., various substances are obtained which are either 



and tests for carbolic acid. 475. What substances are known as terpenes, 

 where are they found in nature, and how are they related to camphors ? 476. 

 What relation exists between benzoic acid and oil of bitter almond? 477. 

 What is the source of amygdalin> to which class of substances does it belong, 

 and what are the products of its decomposition under the influence of emulsine ? 

 478. Explain the process for the manufacture of salicylic acid from phenol, 

 and state its properties. 479. Give composition and properties of naphtalin 

 and naphtol. 480. Give tests for tannin, state the source from which it is 

 derived, and for what it is used. 



