An Improved Process for Producing Colouring Matter from Anthraquinone.
Year: 1887

page_text: Date of Application, 4th Jan., 1887.
Complete Left, 13th Sept., 1887
Complete Accepted, 14th Oct., 1887.
An Improved Process for Producing Colouring Matter from
Anthraquinone.
I, HANS JAKOB WALDER of Unterstrass, near Zürich, Switzerland, Doctor of
Philosophy, do hereby declare the nature of this invention, to be as follows:-
1 part by weight of anthraquinone is heated with 4-5 parts of English sulphuric
acid of 660 B at 260° Centigrade until the mass is capable of dissolving in water to a
clear brown liquid. Subsequently the mass is allowed to cool, diluted with water to
four or five times its volume and filtered to separate such anthraquinone as may
remain unchanged. To the filtrate is added by degrees with constant stirring, solid
potassium nitrite or sodium nitrite in the proportion of two molecules of nitrite to
one molecule of anthraquinone, at the same time not allowing the temperature of
the liquid to exceed 25° Centigrade. When all the nitrite is added and the generation
of red vapour has ceased, common salt in small excess is added, the mass stirred and
left standing a dark brown deposit is thereby produced. If a sufficient quantity of
salt is added, the liquid when filtered gives a wine yellow filtrate. If this is the case
the deposit is accumulated on a filter and washed with cold water until the filtrate
commences to turn darker. Subsequently the deposit is pressed and dried at
100° Centigrade until the mass can be easily pulverised.
One part by weight of the powder is mixed by degrees to two parts of melted
hydrate of potash or soda with continual stirring and the mass is heated until the
foaming up of the mixture ceases and the mixture begins to become pasty. A sample
of this product when dissolved in water and acidified with muriatic acid, should give
a pale yellow-coloured clear filtrate. If the filtrate is of a brown colour, the
beating must be continued if exactly sufficient hydrate of alkali was employed.

page_text: The finished product is allowed to cool and is afterwards dissolved in water. The
brown solution is filtered and the filtrate is mixed with muriatic acid in excess. The
separated colouring matter is accumulated on a filter, well washed with water and
dissolved in diluted solution of soda (1-2 parts of crystal soda to 100 parts of water);
the solution, is filtered and precipitated with muriatic acid. The purified product is
preserved in wet state as a paste.
This colouring substance is soluble in alcalies with a dark brown colour and dyes
cotton, mordanted with alum, red brown.
1000

page_text: Anthraquinone.
I, HANS JAKOB WALDER of Unterstrass near Ztirich, Switzerland, Doctor of
Philosophy, do hereby declare the nature of my invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention consists in a new or improved process for deriving or forming a
coloring matter from or with anthraquinone by the formation of the disulpho-acid
thereof and the subsequent treatment of this product. In carrying this invention
into effect one part by weight of anthraquinone is heated with 4-5 parts of English
sulphuric acid of 66° B. at 260° Centigrade until the mass is capable of dissolving in
water to a clear brown liquid. Subsequently the mass is allowed to cool, diluted
with water to four or five times its volume and filtered to separate such anthraquinone
as may remain unchanged. To the filtrate is added by degrees with constant stirring
solid potassium nitrite or sodium nitrite in the proportion of two molecules of nitrite
to one molecule of anthraquinone, at the same time not allowing the temperature of
the liquid to exceed 25° Centigrade. When all the nitrite is added and the
generation of red vapour has ceased, common salt in small excess is added, the mass
stirred and left standing. A dark brown deposit is thereby produced. If a sufficient
quantity of salt is added, the liquid when filtered gives a wine yellow filtrate. If this
is the case the deposit is accumulated on a filter and washed with cold water until the
filtrate commences to turn darker. Subsequently the deposit is pressed and dried at
100° Centigrade until the mass can be easily pulverised.
One part by weight of the powder is mixed by degrees to two parts of melted
hydrate of potash or soda with continual stirring and the mass is heated until the
foaming up of the mixture ceases and the mixture begins to become pasty. A sample
of this product when dissolved in water and acidified with muriatic acid, should give
a pale yellow colored clear filtrate. If the filtrate is of a brown colour, the heating
must be continued if exactly sufficient hydrate of alkali was employed.
The
The finished product is allowed to cool and is afterwards dissolved in water. The
brown solution is filtered and the filtrate is mixed with muriatic acid in excess.
separated coloring matter is accumulated on a filter, well washed with water and
dissolved in diluted solution of soda (1-2 parts of crystal soda to 100 parts of
water) the solution is filtered and precipitated with muriatic acid. The purified
product is preserved in wet state as a paste.
This coloring substance is soluble in alcalies with a dark brown colour and dyes
cotton mordanted with alum, red brown.

page_text: 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 :-.
In producing coloring matter from or with anthraquinone :
1. The treatment of the disulpho-acid of anthraquinone by or with nitrous acid
or nitrites.
2. The process for producing coloring matter from anthraquinone, consisting in
heating anthraquinone with sulphuric acid to 260° Centigrade and after cooling
diluting the same with water to the quadruple or quintuple volume, adding to the
filtrate resulting therefrom solid nitrite of potassium or sodium subsequently treating
the same with common salt, heating the precipitate at 100° Centigrade with thin
liquid hydrate of potassium or sodium, dissolving the mass with water, and eliminating
the colouring matter by the addition of inuriatic acid.
Dated this 13th day of Santambor 1997
HANS JAKOB WALDER.
By Herbert & Co.,
67, Strand, London, W.C.,
Agents to Applicant.