ANILINE AND ANILINE DYES.—Manufacture of Aniline Oils. 211

When the methylation of the resulting productsis pushed further, as when the heating is effected incontact with excess of methylic alcohol, yet higherliomologues are formed : thus there are formed suc-cessively derivatives of:—

0 ,TT_

Dimethyl aniline, jj j- N ;

Dimethyl toluidine, C^IL, CEL ") XT

(ciyJ N:

Dimethyl xylidine, C 6 H 3 (CH 3 ) 2 1 _

(HH 3 2 ! ’

Dimethyl cumidine, CAL (CHAD

(GH 3 ) 2 j- N =

Dimethyl cymidine, C (i II(ClI ^ 4 )

(cn 3 ) 2 j-

—IIofmann and Marti os.

Amongst the products formed by the carrying outof this action to its limit is a hydrocarbon, apparently

C 0 (CII 8 ) 6 ; whilst a primary amine, ^ 6 ^jj 3 ^ 5 |n,

has been obtained in small quantity by Hofmannamongst the bye products of the action of heat ontrimethyl phenylium iodide.

The occurrence of these reactions has doubtlessa most important bearing on the colour-producingproperties of methyl aniline and dimethyl aniline.Hofmann’s recent researches tend to show that theviolet dye obtained by the oxidation of dimethyl ani-line is identical with that got by methylating rosani-line, produced by oxidizing a mixture of aniline andparatoluidine.

c,n 8 l

Ethyl aniline, C 2 II 6 \ N.—This base is obtain-11 1

able from aniline and ethyl iodide, &c., or from ani-line hydrochloride and ethyl alcohol, in the same wayas methyl aniline is prepared : it is a colourless liquid,boiling at 204° C. Notwithstanding the close connec-tion between the dyes got by oxidizing methylatedanilines and those by methylating rosaniline, ethylaniline does not yield by oxidation any noteworthyquantity of dyes such as those got by ethylatingrosaniline. The following bodies :—

C c HD

Diethyl aniline, 0,, 1 L > N ;

« 2 h 5 )c 0 h 5 1

Amyl aniline, CsUnrif:

H j

C 6 II 4 CH 3 )

diethyl toluidine, C1I 3 >N;

C 6 H 4 CH 3 )

Ethyl toluidine, CAL J. N;

H f

C 0 H 5 )

Dinmyl aniline, C 5 II n vN •

C 5 H 11 )

C 6 II 4 ,CHD

Dimethyl toluidine, CXI., r N :

chJ

and hosts of analogous substances are known, andattempts have been made to utilize some of them ascolour-producing agents, but for the most part withlittle or no success. Methyl toluidine and dimethyltoluidine (both para- and meta-) probably occur inthe mixture of methyl aniline and dimethyl aniline,

which is now largely manufactured for the productionof “Violet de Paris ; ” but they do not contribute tothe improvement of the dye, and it is a great objectto obtain an aniline free from higher liomologues forthis particular purpose. Aniline containing more than

5 per cent, of toluidine is unsuitable for the produc-tion of Violet de Paris (Lactii).

C PI Cl)

Chloraniline, " 6 jj | N, and its liomologues

have been proposed as sources of colouring mattersby Poulain. When a mixture of chloraniline andchlorotoluidine is heated, hydrochloric acid and rosan-iline are formed. The chlorinated bases are obtained,in the first instance, by acting on benzene with iodineand chlorine, when chlorobenzene is formed; thisis then nitrated and converted into a chlorinatedaniline oil in the usual way (Vide article Benzol ).

By acting on these chlorinated bases with iodide of

C G II. 2 C1)

methyl, ethyl, &c., methyl chloraniline, CII,,)- N,

and analogous products are formed; and by the with-drawal of the elements of hydrochloric acid fromthese substances, or mixtures of them, other dyestuffscan be produced.

MANUFACTURE OF ANILINE OILS.

The various kinds of aniline oils (including in thisterm the commercial bodies sold as aniline, toluidine,xylidine, and their mixtures) are all prepared in thesame way, the sole difference being in the natureof the nitrobenzol used, i.e., in the character of thehydrocarbon or “benzol” used in the first instance.

The method first tried on the large scale (by Messrs.Simrson, Maule, and Nicholson) was that of Zinin,viz., the action of sulphuretted hydrogen on the solu-tion of nitrobenzol in ammoniacal alcohol. The alco-holic solution, placed in a digester furnished with acondensing worm, was first saturated with ammoniagas, and then sulphuretted hydrogen was led in tosaturation; the temperature was then raised to 100 °

C. by a steam worm, the taps of the digester beingclosed, so that the pressure was considerable. In afew hours all odour of sulphuretted hydrogen disap-peared, that of ammonia only remaining; the liquidwas then cooled, and again saturated with sulphur-etted hydrogen and heated to 100° C. When thereaction was completed (which was known by the per-fect solubility in dilute hydrochloric acid of a smallsample drawn from time to time as a test), the am-moniacal alcohol was distilled off and used over again,the aniline remaining in the still, mixed with sulphurfrom the decomposition of the sulphuretted hydrogen;thus, in the case of aniline:—

Nitrobenzene. Aniline.

C 6 II 5 ,N0 2 + 3H 2 S = C c II 5 ,NII 2 + 2II 3 0 + 3Sand similarly for the higher homologues.

r l he inconvenience of this method and its compara-tive costliness soon led to its abandonment; the samemay also be said of the process invented by IIof.mannand worked for a time by E. Kopp, viz., the additionto nitrobenzol (contained in a still) of zinc (in lumps),and the gradual addition of slightly diluted hydro-