IMPROVEMENTS IN THE MANUFACTURE OF COLORING MATTERS
Year: 1884

page_text: I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co., Patent Agents,
Southampton Buildings, in the County of Middlesex do hereby declare the nature
of said invention for "IMPROVEMENTS IN THE MANUFACTURE OF COLORING
MATTERS to be as follows:-
ม
This invention relates to the manufacture of brown, black, blue, violet and red
coloring matters, applicable for dyeing and printing textile or fibrous materials,
more especially cotton.
These coloring matters are obtained in a general manner by subjecting amido-azo-
benzol (amidoazobenzol) and its homologues amido-azo-toluol (amidoazotoluol),
amido-azo-benzo-toluol (amidoazobenzotoluol), and like substances such as sulpho-
amido-azo-benzol (sulfo-amido-azobenzol), to a reducing action and subsequently
oxidizing the bases thus obtained.
Various processes can be employed for reducing the amido-azo-benzol (amido-
azobenzol), among which I will mention the employment of iron and acetic acid,
of zinc and hydrochloric acid, or of sulphuretted hydrogen in acid solution.
I may, however, make use of any method of reduction known in chemistry.
In this manner colorless bases are obtained which are capable of producing by
oxidation coloring matters whose shade or color varies from violet red to greenish
blue, and from black to chestnut.
Amongst the oxidizing agents which I can employ with advantage I will
mention bichromate of potash, perchloride of iron, permanganate of potash, peroxide
of barium, free oxygen, atmospheric air, and in general most of the oxidizing
agents.
The coloring matters obtained have a great affinity for cotton; they have,
moreover, the property of resisting the action of alkaline solutions, air, and
light.
Example:-
I heat to from 60 to 80 degrees centigrade a mixture formed of

page_text: hydrochlorate of amido-azo-benzol (chlorhydrate D¹ amidoazobenzol) is dissolved
and the liquid no longer contains any insoluble matter except a sediment of sulphur.
At this moment the liquid has nearly lost the deep red color which it possessed
at first.
The sulphur is eliminated by filtering; the filtered liquid contains the new base
in acid solution.
It suffices afterwards to oxidize this liquid in order to produce the coloring
matter; for this purpose a solution of perchloride of iron is added by degrees until
the color obtained no longer increases in intensity. The liquid is ready without
any further treatment for dyeing suitably mordanted cotton. We may, if desired,
immerse the mordanted floats of cotton in the acid solution of the base, in which
case the oxygen of the air is sufficient to develop the coloring matter. The solution
of the base behaves in this case like a pure indigo dye. On the other hand, the
coloring matter may be isolated by precipitation, dried and reduced to powder.

page_text: COMPLETE SPECIFICATION.
I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co, Patent
Agents, Southampton Buildings, in the County of Middlesex, do hereby declare
the nature of my invention for "IMPROVEMENTS IN THE MANUFACTURE
COLORING MATTERS and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
"
OF
This invention relates to the preparation of blue and violet colouring matters
derived from the amido-azobenzol (amidoazobenzol) its homologues and its
substitution products.
The French chemist Ch. Lauth has obtained a series of colours by causing
sulphuretted hydrogen and perchloride of iron to act in turn upon aromatic
diamines (diamines aromatiques) (Bulletin de la Société Chimique de Paris,
A.D. 1876 2nd half-year, vol 26, page 422).
In this manner sulphuretted bases are formed capable of giving by oxidation
very beautiful violet colours.
For want of a sufficiently economical process for preparing paraphenyline
diamine (paraphenyline diamine), the discovery of Lauth, who took nitracetaniline
(nitracetaniline) as a basis, has not given, from an industrial point of view, the
results which were anticipated.
The "Badische Anilin und Soda fabrik" has patented a method of preparing
the dimethylated derivative of the colour of Lauth, with nitrosodimethylaniline
(nitrosodimethylaniline) as a basis. This substance, when reduced by sulphuretted
hydrogen, gave amidodimethylaniline (amidodimethylaniline) which, subjected
alternately to the action of sulphuretted hydrogen and of perchloride of iron,
produced a blue colouring matter (termed methylene blue) (bleu methylene).
This discovery forms the subject of German Patent No 1886, dated the
15th December 1877.
The communicators of this invention have discovered that amidoazobenzol
(amidoazobenzol) and its homologues, amidoazotoluol (amidoazotoluol) etc,
substances which, in chemical industry, are prepared at a cheap rate, could form
the basis of an important series of colouring matters.
By reducing amidoazobenzol, (amidoazobenzol) paraphenylene diamine (para-
phenylene diamine) is obtained which latter is converted by the action of sulphur
into a thiobase. and by oxidation, by means of perchloride of iron, into blue
colouring matter.
The homologues of amidoazobenzol (amidoazobenzol) amidoazobenzotoluol
(amidoazobenzotoluol) amidoazotoluol, (amidoazotoluol) amidoazoxylol (amido-
azoxylol) etc, and their substitution products monosulphoamidoazobenzol (monosulfo
amidoazobenzol) etc can also be reduced in a similar manner, the bases obtained
being converted equally well into thiobases and giving by oxidation violet colours
which in dyeing and calico-printing are capable of numerous applications.
The present process comprises three distinct operations, viz:—
1st formation of diamines.

page_text: in the preparation of the paraphenylene-diamine a mixture, composed or
50 parts of hydrochlorate of amidoazobenzol,
of hydrochloric acid 22°, and
400
»
500
"
of water,
is heated to, say, from 40° to 50° Centigrade.
To this mixture is added by degrees (care being taken to stir during the
operation) a solution of sulphuret of sodium, until the reduction is complete, that is
to say,
until all the hydrochlorate of amidoazobenzol is dissolved and the liquid no
longer contains insoluble substances except a deposit of sulphur.
The liquid, which has now almost lost the dark red colour it had, is filtered in
order to eliminate the sulphur. The liquid contains the new base in acid solution.
Other reducing agents than sulphuretted hydrogen are sometimes employed; for
instance tin and hydrochloric acid, zinc and hydrochloric acid, zinc in the form of
powder, iron and acetic acid, etc, and it is likewise possible to effect the reduction
of amidoazobenzol in other vehicles than water; for this purpose aniline, alcohol,
concentrated acids, etc. can be used.
The paraphenylene-diamine obtained by the means above mentioned is converted
into a thiobase either by a wet process by means of a prolonged current of
sulphuretted hydrogen; or by a dry process by melting or dissolving I moleculé
of paraphenylene-diamine with 1 molecule of sulphur according to the indications
given by Lauth.
For the formation of the colouring matter it is sufficient to add an oxidizing
agent to the thiobase formed, the oxidizing agents which can be employed are
perchloride of iron, bichromate of potash, etc. in aqueous solution.
In a given solution of hydrochlorate of thioparaphenylenediamine containing an
excess of acid, the quantity of the oxidizing agent to be employed is determined by
experiment. The colour forms instantaneously, and is easily obtained by
precipitation by means of sea salt (sel marin). It is necessary to effect this
oxidation in a diluted and cooled solution.
By employing alternately sulphuretted hydrogen and perchloride of iron, it is
possible to obtain the colouring matter directly from paraphenylene-diamine
according to a known process.
If amidoazobenzol is taken as the basis, a blue colour is obtained; amidoazo-
benzotoluol gives a violet-blue colour and amidoazotoluol a violet colour. These
colouring matters easily yield methylated or ethylated and similar substitution
products by employing known processes for effecting the substitutions.
All these colours fix easily upon textile fibres particularly mordanted' cotton and
give beautiful tints, which are not affected by light or by soap:
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
The process hereinbefore described of preparing blue and violet colouring matters
by reducing amidoazobenzol and its homologues, and oxidizing the thiobases
obtained from the products of this reduction.