IMPROVEMENTS IN THE MANUFACTURE OF A YELLOW COLOURING MATTER FROM BENZOLE
Year: 1879

page_text: LETTERS PATENT to Frank Wirth, of the Firm of Wirth & Company,
Patent Solicitors, at Frankfort on the Main, in the Empire of Germany, for
the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF A YELLOW
COLOURING MATTER FROM BENZOLE." A communication from Friedrich
Graessler, of Cannstadt, in the Kingdom of Wurtemberg.
Sealed the 1st July 1879, and dated the 3rd January 1879.
PROVISIONAL SPECIFICATION left by the said Frank Wirth at the Office
of the Commissioners of Patents on the 3rd January 1879.
FRANK WIRTH, of the Firm of Wirth and Company, Patent Solicitors, at
Frankfort on the Main, in the Empire of Germany. "IMPROVEMENTS IN THE
MANUFACTURE OF A YELLOW COLOURING NATTER FROM BENZOLE." [A com-
munication from Friedrich Graessler, of Cannstadt, in the Kingdom of Wurttemberg.]
My Invention has for its object a new and improved method of production of a
new yellow colouring matter from aniline and its homologous compounds to be
applied to the dyeing of textile fibres or fabrics in a solid and permanent manner
by the aid of acids or acid mordaunts, or to printing as an alkaline salt.
To effect this purpose it is necessary to render this colouring matter soluble in
water and alkalis.
For this object I treat aniline with nitrous acid after a well known process to
produce the benzol compound C, H, N₁, generally called amydiazobenzol
This amydiazobenzol I then treat with fuming sulphuric acid, taking one part of
the former to four parts of the latter, and allow them to stand after mixing together
until the whole is soluble in alkali.
In this way is formed amydiazobenzol sulpho acid, which is my improved colouring
matter.
By filtering and washing I get this matter in a state to be employed for dyeing
and printing, either as the sulpho acid or as its alkaline salt by mixing with
alkali

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Frank Wirth in the Great Seal Patent Office on the 2nd July
1879.
FRANK WIRTH, of the Firm of Wirth & Company, Patent Solicitors, at
Frankfort on the Main, in the Empire of Germany. "IMPROVEMENTS IN THE
MANUFACTURE OF A YELLOW COLOURING MATTER FROM BENZOLE" A communi-
cation from Friedrich Graessler, of Cannstadt, in the Kingdom of Wurtemburg.
My Invention has for its object a new and improved method of production of a
new yellow colouring matter from aniline and its homologous compounds to be
applied to the dyeing of textile fibres or fabrics in a solid and permanent manner
by the aid of acids or acid mordaunts, or to printing as an alkalino salt.
To effect this purpose it is necessary to render this colouring matter soluble in
water and alkalies.
For this object I treat aniline with nitrous acid after a well known process to
produce tho benzol compound C₁, H₁, N₁, generally called amydiazobenzol.
This amydiazobenzol I then treat with fuming sulphuric acid, taking one part of
the former to four parts of the latter, and allow them to stand after mixing together
until the whole is soluble in alkali.
In this way is formed amydiazobenzol sulpho acid, which is my improved colouring
matter.
By filtering and washing I get this matter in a state to be employed for dyeing
and printing, either as the sulpho acid or as its alkaline salt, by mixing with
alkali.
And in order that my Invention may be the better understood I now proceed to
detail some examples of more exact reactions by which my colouring matter may
be obtained.
The preparation of the intermediate compound known as amyidazobenzol of the
formula C, H, N., is most conveniently effected by the action of nitrous acid on
aniline, or of nitrites on aniline salts. The chief products of this reaction are two
isomeric derivatives; of these, one which I call diazoamydobenzol is decomposed by
acids, and therefore not suitable for my further treatment; the other is the afore-
said amydiazobenzol which is able to form salts with acids, and is very convenient
for transformation into amydiazo sulpho acid which it is my object to produce,
and to which my Patent rights relate.
As an example of a method of preparation by which I obtain the above
indicated amydiazobenzol, when employing nitrites I mix one part of com-
mercial aniline, tholuidine, or other homologous bodies, or a mixture of the same,
one part of aniline salt (chlorhydrate of aniline or any of its homologous bodies),
and one half part of nitrite of sodium (or another nitrite of corresponding weight)
dissolved in water, and this I do at a moderate temperature so that the nitrous acid
enters perfectly into combination with the aniline.
The first or primitivo product of this reaction may be considered to be diazo-
amydobenzol, but this passes by prolonged contact with aniline into the said
amydiazobenzol. To produce the latter effect I allow the mixture to stand until it
shows, by combining with acids, the salt forming power of the amidiazobenzol.
It is then mixed with hydrochloric acid and water to bring into solution the rest
of the aniline, and to precipitate the formed amydiazobenzol as chlorhydrate, which
is filtered and dried.
As before stated, amydiazobenzol is already known as a colouring matter, but to
a certain degree of unstable character, the salts being too casily decomposed by
water, and the base having little affinity for textile fabrics.
The sulpho-acid compounds I have found by research do not partake of these
inconvenient qualities, and it is therefore the practical preparation of a sulpho-acid

page_text: of amydiazobenzol from that latter body which itself may be prepared, as described,
above that I now describe and claim.
To prepare the said sulpho-acid I gradually add one part of amydiazobenzol or
one of its salts (preferably the chlorhydrate as hereinbefore described) to three to
five parts of strong fuming sulphuric acid, or any compound or mixture containing
an hydro-sulphuric acid in any active form, at ordinary temperature; or should the
sulphuric acid prove not strong enough to dissolve at this temperature, the mass
may be heated not over 90° to 100° centrigrade, till a test shows that the product is
entirely soluble in alkali and water, and therefore transformed perfectly into the
sulpho acid.
The whole is then thrown into water or saline solution, the excess of acid employed
washed away or saturated by alkalies, and separated by filtering from the now
formed sulpho acid of amydiazobenzol.
To obtain this latter in a form convenient for use and sale it may be mixed with
a solution of alkali in order to produce an alkaline salt, and finally evaporated,
dried, and powdered.
I do not limit myself to this method of preparation alone, the object of my
improvement being to produce a sulpho acid of amydiazobenzol for the novel
purposes herein described.
Another manner in which this preparation may be effected is analytical instead
of synthetical, as herein before described, as for example,-
I may use the known product of sulpho-anilic acid, and produce from this
gradually the sulpho-acid of amydiazobenzol that I require for my improved colouring
matter.
The sulpho-anilic acid or sulphanil acid (C, H, N, SO,H,) may be obtained, as
is well known, by the action of sulphuric acid on aniline at a high temperature.
Then to about four parts of this sulphanil acid add three parts of hydrochloric
acid of 1.15 sp. gravity, and two parts of nitrite of sodium in aqueous solution.
Thus is formed the sulpho-diazo-benzolic acid known to have the formula
C₁, H., N., SO,.
To this I add about two to three parts of aniline, and allow the whole to stand
at a temperature of 30° to 40° centigrade till, as a final product of the reaction, is
formed again the sulpho-acid of the amydiazobenzol identical with that already
described as obtained by the first reaction.
The unengaged remainder of the aniline may be taken away by hydrochloric
acid, and the sulpho-acid may be precipitated by common salt and finally treated
as before described.
In all the processes hereinbefore described aniline may be replaced by tholuidine
or other homologous bodies with the same effect.
Having now described and particularly ascertained the nature of my Invention,
and the way in which it may be carried into effect, I wish it clearly understood
that I do not restrict myself to the exact proportions or re-agents mentioned herein,
but that what I claim is the production of an improved and convenient yellow
colouring matter representing in its chemical constitution a sulpho-acid of amydiazo-
benzol or its homologous bodies, substantially as herein described.
In witness whereof I, the said Frank Wirth, have hereunto set my hand and
seal, this Twenty fifth day of June, in the year of our Lord One thousand
eight hundred and seventy nine.
FRANK WIRTH (LS.)