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THE

CHEMICAL NEWS

AND

JOURNAL OF PHYSICAL SCIENCE.

(WITH WHICH IS INCORPORATED THE “CHEMICAL GAZETTE.")

A Journal of Practical Chemistry

IN ALL ITS APPLICATIONS TO

PHARMACY, ARTS, AND MANUFACTURES.

EDITED BY

WILLIAM CROOKES, F.R.S., &c.

VOLUME XXVII.—1873.

LONDON:

HENRY GILLMAN, BOY COURT, LUDGATE HILI, E.C.

AND SOLD BY ALL BOOKSELLERS,

MDCCLXXIII.

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THE CHEMICAL NEWS.

VOLUME

XXVII.

EDITED BY WILLIAM CROOKES, F.R.S., &c.

No. 684.-FRIDAY, JANUARY 3, 1873.

an

SYNTHESIS OF AROMATIC MONAMINES BY | phenylamine or dimethyl toluidine ; this, in a second INTRAMOLECULAR ATOMIC INTERCHANGE.*

phase of the reaction, becomes iodhydrate of mono

methylated dimethylophenylamine or xylidine, which in By A. W. HOFMANN, M.D., LL.D., F.R.S.

its turn is ultimately converted into iodhydrate of trime

thylophenylamine, i.c., of cumidine. The essential In a paper submitted to the German Chemical Society character of the reaction is thus seen to be an intermoleabout a year ago, we proved (Dr. Martius and myselft) cular change in the position of the methyl groups. that the action of methylic alcohol on aniline chlorhy. According to the duration of the process, there are incordrate at a high temperature and under pressure, far from porated in the benzol nucleus, first the methyl group of yielding exclusively' methyl- and dimethylaniline, as has the alcohol iodide, and then successively the two methylic been formerly believed, is capable of causing methylation groups which are stationed in the ammonia fragments. of the phenyl group, and thus producing quite a series of The action of heat on the quartary ammonium compound higher homologues of dimethylaniline.

thus places at our disposal a simple means of rising from If we endeavour to gain an insight into the mechanism the benzol series itself to the toluol., xylol., and cumol of this reaction, we are led to assume that in the first series, or, generally (for the reaction may probably be instance the chlorhydric acid of the aniline salt gives rise utilised in many other cases), of passing from a less

carbonated to a inore carbonated series of compounds. to the formation of methylic chloride, which in its turn induces substitution, first in the ammonia fragment, and ultimately in the phenyl group itself. If, on the other

In carrying out the researches, the general results of hand, we remember that a tertiary monamine, such as must be formed by the final methylation of the ammonia frag- considerable quantities of trimethylated phenylammo

which are sketched in the preceding paragraphs, rather ment in aniline when submitted to the nation of an

nium iodide were consumed. This I obtained partly by alcohol chloride, is invariably converted into ammonium compound, it must appear rather strange that starting from commercial dimethylaniline, which was

methylating pure aniline with methyl iodine, partly by in the process above alluded to only tertiary, and never

most liberally supplied to me by my friends Dr. D. any quartary bases are observed.

Martius and Mendelssohn Under these circumstances the idea very naturally sug- specially purified for this purpose by Mr. G. Krell, by

Bartholdy, having been gested itself of submitting the behaviour of quartary fractional distillation in the laboratory of the factory: compounds at a high temperature under pressure to an

This purified material was found to boil between 192o and experimental investigation. The simplest compound that could be detected for such 200°; and only few rectifications were necessary in order

to obtain from it dimethyaniline in a state of perfect an inquiry appeared to be trimethylphenylammonium purity, identical in every respect with the base prepared iodide, C.H.CH3.CH3.CH3NI. Reserving for a future communication the experimental distillation. °Pure dimethylaniline is a liquid of oʻ9553

by submitting trimethylated phenylammonium hydrate to details of this inquiry, I will limit myself for the present V.W., solidifying to a crystalline mass at +0.5°, and to a brief statement of the principal result obtained. Leaving secondary reactions out of consideration, the mined, since it had been erroneously stated by M. Louth*

boiling at 192o. The boiling-point was repeatedly detertransformation of the trimethylated phenylammonium to be 202°. The nature of the compound was ascer. iodide is represented by the following equations :

tained by the analysis of the beautiful platinum-salt Transformation of quartary into tertiary compound. 2{C6H5(CH3)2N.HCI]. PtCl4, crystallising in well-formed C6H5.CHZ.CHZ.CHZ.NI=(C6H4.CH)CH3.CHZN.HI.

tables of considerable solubility.

In the early experiments trimethylated phenylammoTransformation of tertiary into secondary compound. nium iodide was employed in the pure state, such as (C6H.CH3)CH3.CH3.N.HI =

is obtained by crystallisation; subsequently, however, C6H (CH(CH3)4] CH.HNHI.

it was found to be quite sufficient if i mol. of dimethyl

aniline was niixed with i mol. of methyl iodide, and the Transformation of secondary into primary compound. compound thus produced at once submitted to the action

(C6H3(CH3)2]CH3.HN.HI= [C6H2(CH3)3] HHN.HI. of heat. Accordingly trimethylated phenylammonium iodide,

The quartary iodides may be exposed to a temperature when submitted to the action of heat, is transformed in

of 200° for a considerable time without undergoing any the first place into iodhydrate of dimethylated methylo- alteration; but when heated for a day to from 220to

230°, the salt is changed, the whole crystalline compound * A paper read before the Royal Society. 1 Hofmann and Martius, Bericht, 1871, p. 742.

* Louth, Bill. Soc. Chin. (2) vol. vii., page 448.

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