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Reaction (expressed in the form of equation):

C6H6+2 Br= CH,Br+ HBr

Benzene.

Monobromobenzene.

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Properties.-Colourless liquid ; boiling-point 154°—

155°; specific gravity 1'5176 at 0°.

PREPARATION II.

ETHYL BENZENE, CH10 CH5.C2H5.

LITERATURE.-Fittig (1864), Ann. Ch. Pharm. 131, 303; Fittig, König (1867), Ann. Ch. Pharm. 144, 277.

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A quantity of pure ether (about twice the volume of the mixed phenyl and ethyl bromides) is poured into a round-bottomed flask, about litre capacity, con

nected with a reflux condenser. 26'5 grms. clean sodium cut into thin slices are added to the ether, and when all evolution of hydrogen has ceased the flask is immersed in a vessel of water which is cooled by the addition of ice (Fig. 10). The mixture of 60 grms. bromobenzene and 52 grms. ethyl bromide, both of which must be perfectly anhydrous, is poured

into the flask. The reaction is allowed to commence spontaneously, the fact being indicated by the sodium becoming darker in colour and sinking to the bottom of the vessel. Although the flask is allowed to remain in the outer vessel, and is cooled by water and ice, the heat evolved in the reaction often causes the ether

FIG. 10.

to boil. The flask is, therefore, not removed from this vessel until the reaction is over. The ether is then distilled off on the water-bath, and the ethyl benzene is driven over as quickly as possible by using a naked flame, the vessel being first gently heated round the sides, and finally more strongly from below, until no

more liquid distils. The distillate, containing ether and benzene, is rectified, and the portion boiling at 132°— 135° collected.

C6H5Br+C,H,Br + 2 Na = CH5. C2H5 + 2 Na Br

Bromobenzene Ethylbromide

Ethylbenzene.

Properties.-Colourless liquid; b. p. 134°; sp. gr.

•8664 at 22'5°.

PREPARATION III.

NITROBENZENE, C,H,NO2.

LITERATURE.-Mitscherlich (1834), Ann. Ch. Pharm.

12, 305; Mulder (1840), Journ. prakt. Ch. 19, 375.

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A well-cooled mixture of 100 grms. conc. nitric acid, and 150 grms. conc. sulphuric acid is slowly added from a tap-funnel to 50 grms. benzene contained in a flask of about litre capacity.* The contents of the flask are meanwhile well shaken. Nitrous fumes are evolved, and a considerable amount of heat developed. Care must be taken that the temperature does not exceed 40°—50° by immersing the flask, if necessary, in cold water. The nitrobenzene separates out as a brown, oily layer on the surface of the acid

C

liquid. When the acid has all been added-an operation which lasts about half an hour-the mixture is heated for about twenty minutes on the water-bath to 60°-70° and again well shaken. The contents of the flask on cooling are poured into a stopperedseparating funnel, the lower layer of acid removed, and the nitrobenzene washed free from acid by shaking repeatedly with water, then with dilute carbonate of

FIG. II.

The

soda solution, and again with water, the oil being each time withdrawn from the bottom of the vessel. nitrobenzene, separated as carefully as possible from water, is allowed to stand over a few pieces of fused calcium chloride, and shaken occasionally until the liquid is perfectly clear.

The yellow liquid is decanted from the calcium. chloride and distilled in a dry distilling flask, the side tube of which fits into a long, straight, condensing

tube (Fig. 11). At first a little benzene passes over, the temperature then rises, and the nitrobenzene distils at 204°—207°, and is separately collected. The brown residue contains a small quantity of dinitrobenzene.

CH6+ HONO2 = CH5NO2 + H2O
Nitrobenzene.

Benzene

The function of the sulphuric acid is that of a dehydrating agent, taking up the water formed in the reaction.

Properties.-Light yellow liquid, smelling of bitter almonds; b. p. 206°-207°; sp. gr. 1208 at 15°; it solidifies at +3°; insoluble in water; soluble in alcohol, ether, benzene, and conc. nitric acid.

PREPARATION IV.

6

ANILINE, CH,N=C2H,.NH2
(Amidobenzene, Phenylamine.)

Literature.-Unverdorben (1826), Pogg. Ann. 8, 397; Runge (1834), Pogg. Ann. 31, 65; Fritsche (1840), Ann. Ch. Pharm. 36, 84, and 39, 76; Zinin (1842), Ann. Ch. Pharm. 44, 283; Hofmann (1844), Ann. Ch. Pharm. 47, 37; Roussin (1861), Jahresb. 643.

60 grms. nitrobenzene.

95

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350

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tin (granulated or in powder).
conc. hydrochloric acid.

Sixty grms. nitrobenzene and 95 grms. granulated or powdered tin, are placed in a flask of about 1 litre

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