502 CLASSIFICATION OF BASES-ANILINE. Lastly, the formation of organic bases has been observed during processes of fermentation and putrefaction;-the putrefaction of wheaten flour, for example, furnishing trimethylia, ethylia, and amylia. (1361) The following order will be observed in the description of such of the organic bases as, from their important applications, their bearing upon other groups, or from the mode of their formation, seem to be most worthy of notice : 2. Bases obtained by the action of ammonia on derivatives of the alcohols. 3. Bases derived from phosphuretted hydrogen. 4. Polyatomic bases. 5. Bases obtained by the action of ammonia upon certain essential oils. B. Natural Bases. 1. Volatile oily bases destitute of oxygen :— 2. Oxidized bases :- a. Bases from the cinchonas; b. Bases from opium; c. Bases from pepper; d. Bases from the strychnos tribe; e. Other less known bases; f. Caffeine and theobromine. A. ARTIFICIAL BASES. 1. Volatile Bases which do not contain Oxygen. a. Aniline Series (ЄnH2n-7)'H2N. 12 (1362) ANILINE, Kyanol, Phenylamine, Phenylia, Crystalline, or Benzidam (H,H2N or C12H,N=93); Sp. gr. of liquid 1'020; of vapour, 3210; Rel. wt. 46'5; Boiling pt. 360° (182° C.).— This remarkable base may be prepared from several sources, and by a variety of reactions : ANILINE-MODES OF PREPARATION. 503 1. It is contained in small quantity among the products of the destructive distillation of coal in the process of gas-making. 2. Nitrobenzol is converted by sulphide of ammonium into aniline and water, sulphuretted hydrogen being decomposed, whilst sulphur is deposited : 2 ¤ ̧H ̧NO2+6 H2S=2 (¤ ̧H ̧,H,N) +4 H2O+3 S2. 2 A similar reduction takes place under the influence of a mixture of zinc and hydrochloric acid, or of iron and acetic acid. Aniline is now manufactured on a large scale for the dyer by the following process (Hofmann, Jury report, 1862, p. 123):— To a mixture consisting of about equal weights of nitrobenzol and strong acetic acid, iron filings or borings are gradually added, taking care that the temperature does not rise too high. The semi-solid mass, which consists chiefly of ferrous acetate and aniline acetate, is distilled either alone or with the addition of lime in iron cylinders, which are gradually raised to a red heat. A mixture consisting chiefly of aniline, acetone, and unchanged nitrobenzol comes over. The product is redistilled, and the portions which distil between 347° and 374° furnish aniline sufficiently pure for commercial purposes. 3. It is also furnished by the distillation, with lime, of nitrotoluol, or of its metamerides, salicylamide and anthranilic acid, all of which substances furnish aniline and carbonic acid; thus : €,H,NO, +Єa = Єa¤¤ ̧ + ЄH,,H,N. The product from salicylamide is always accompanied by carbolic acid (H.). 6 4. One of the methods by which aniline is easily procured consists in submitting to distillation a mixture of a concentrated solution of caustic potash with finely-powdered indigo obtained from the Indigofera anil amongst other plants, whence the name aniline is derived: the mass swells up greatly, and water holding ammonia in solution passes over, accompanied by aniline in the form of a brownish oil. This oil, when re-distilled, furnishes pure aniline, amounting to nearly one-fifth of the weight of the indigo. The history of aniline affords one of the most remarkable instances of the value of scientific chemical research when perseveringly and skilfully applied, for at first few substances seemed to promise less; and the gigantic manufacturing industry at present connected with this compound in its applications as a tinctorial agent offers a singular contrast to the early experiments upon this body when a few ounces of the base furnished a supply which exceeded the most sanguine expectations of the early discoverers of the body. Aniline is a nearly colourless, limpid liquid, of an agreeable vinous odour, and an aromatic burning taste. It is very acrid and poisonous. Aniline remains fluid at -4° (-20° C.). When dropped upon paper it produces a greasy stain, which, owing to the volatility of the base, speedily disappears. Aniline is a non-conductor of electricity; it refracts light powerfully. When exposed to the air it absorbs oxygen rapidly, and becomes converted into a brown resinous mass; it is therefore necessary to distil it in a current of hydrogen, or of carbonic anhydride. It also distils over easily along with the vapour of water, when solutions of its salts are mixed with an excess of potash and submitted to distillation. Aniline is heavier than water, in which it is soluble to a considerable extent; but on saturating the liquid with certain salts, such as sodic chloride or magnesic sulphate, the aniline is separated. Aniline has little or no action on test papers; it may be dissolved in unlimited quantity by alcohol, ether, and wood spirit. Most of the salts of aniline crystallize readily. They are colourless, but if exposed to the air whilst moist, they become rose-coloured. If a slip of deal be plunged into a solution of any of these salts, it gradually acquires an intense yellow colour. If an aqueous solution of a salt of aniline be mixed with a solution of chloride of lime, a deep blue colour is produced, which gradually passes into a dirty red. With chromic acid these salts strike a green, a blue, or a black colour, according to the degree of concentration of the solutions. The methods of procuring these colours will be considered after the salts of aniline itself have been described. Aniline produces a white precipitate in a solution of corrosive sublimate, and a green crystalline precipitate in one of cupric chloride. Both precipitates contain aniline in combination with the metallic chlorides. When a solution of aniline hydrochlorate is mixed with one of nitrite of silver, nitrogen escapes in abundance, whilst carbolic acid is separated in oily drops; this decomposition is due to the reaction of nitrous acid on aniline, which may be thus represented : DERIVATIVES OF ANILINE. 6 505 Aniline acts powerfully upon the hydriodic ethers of the different alcohols, in the manner hereafter to be explained (p. 519), and yields derived bases, such as ethylaniline [(Є2H ̧‚¤ ̧H,H)N]. When mixed with the oxychlorides, or with the anhydrides of the organic acids, aniline yields compounds which correspond with the amides. With acetyl chloride, for instance, it produces acetanilide, and aniline hydrochlorate: Acetyl chloride. Acetanilide. Aniline hydrochlorate. Aniline. CI+ 2H,N=HN+H,N,HCl. H (1363) Aniline forms anilidated acids, anilides, dianilides, and aniles. The aniles correspond to the imides of the ammonia group; they contain the elements of 1 molecule of a dibasic acid and 1 of aniline, minus water, in the proportion of 2 H2O. The anilidated acids, which correspond to the amidated acids, are formed from I molecule of a dibasic acid and 1 of aniline, with the separation of 2 H,. The compounds enumerated in the following list afford examples of each of these classes of 6 Anilidated Acids. 2 Aniles. 6 5/2 2 2 4 3 5 4 4 2 14 2 Acetanilide [(ЄH,,HN‚¤ ̧н ̧‡); Fusing pt. 233°·6 (112° C.)] . may be taken as the representative of the class of anilides. It 506 ensues. ACETANILIDE-CHLORANILINE. may be prepared by acting upon aniline with acetyl chloride, which is to be added drop by drop to the aniline as long as decomposition Aniline hydrochlorate is formed, and may be removed by washing the product with water; acetanilide remains in the form of a yellowish sticky mass of resinoid appearance, which may be obtained in colourless brilliant prismatic crystals, by dissolving it in hot water, and allowing the liquid to cool; alcohol and ether also dissolve it. A still easier method of preparing it consists in cohobating aniline with glacial acetic acid for some hours (G. Williams). Acetanilide melts readily to a yellowish oily-looking liquid, which, on cooling, solidifies to a crystalline mass. It may be distilled without decomposition. When fused with caustic potash, aniline is liberated. Aniline combines directly with cyanogen, and forms a feeble base, termed cyaniline (E,H,N2), which is easily obtained by transmitting a current of cyanogen in excess through a solution of aniline in alcohol; it contains the elements of 1 atom of aniline with I of cyanogen. It may be procured in beautiful white pearly crystals by recrystallization from hot alcohol: when united with acids it is very unstable. Aniline is remarkable as yielding compounds possessed of basic properties, when portions of the hydrogen in its phenyl radicle are displaced by chlorine or by bromine. The first two of these compounds are best obtained by decomposing chlorisatin and dichlorisatin, by means of caustic potash (p. 71). Trichlor. aniline is procured by acting upon aniline by means of chlorine, which converts the aniline at first into a purple compound, and then into a sticky tar-like mass; a quantity of trichlorophenic acid (HЄH2C) is formed at the same time, but the trichloraniline may be obtained in a state of purity by distilling the mixture with a solution of potash, which retains the acid, while trichloraniline passes over and is condensed in delicate needles. 2 Chloraniline (HCl,H,N) is a weaker base than aniline, and is obtained in white, fusible, volatilizable, crystalline needles : its salts have a strong disposition to crystallize; and, like those of aniline, they impart a yellow colour to a slip of deal. Dichloraniline (HCl,,H,N) is still less basic in its characters than the foregoing substance; and trichloraniline (EH,Cl,,H,N) is a very volatile crystalline compound, which is entirely devoid of basic properties. The corresponding compounds with bromine closely resemble the chlorinated forms of aniline in general properties. 2 The action of chlorine in these cases is very interesting: although the introduction of a single atom of this body into |