IMPROVEMENTS IN PREPARING COLORING MATTERS
Year: 1869

page_text: LETTERS PATENT to Heinrich Caro, of Mannheim, Grand Duchy of
Bade, Chemist, Charles Graebe, of Berlin, Kingdom of Prussia,
Chemist, and Charles Liebermann, of Berlin, Chemist, for the In-
vention of "IMPROVEMENTS IN PREPARING COLORING MATTERS."
PROVISIONAL SPECIFICATION left by the said Heinrich Caro, Charles
Graebe, and Charles Liebermann at the Office of the Commissioners
of Patents, with their Petition, on the 25th June 1869.
We, HEINRICH CARO, of Mannheim, Grand Duchy of Bade, Chemist;
CHARLES GRAEBE, of Berlin, Kingdom of Prussia, Chemist, and CHARLES
LIEBERMANN, of Berlin, Chemist, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN PREPARING COLORING MATTERS," to be
as follows:-
This Invention relates to improvements on an Invention for which
Letter's Patent were granted to Charles Liebermann and Charles Gruebe
[Price 8d.]
j

page_text: for Improvements in Preparing Coloring Matters," dated the 18th day
of December 1868, No. 8850, in which the preparation of artificial
alizarine is based upon the action of caustic alkalies upon bibroman-
thrakinon or bichloranthrakinon. We have now discovered that a
similar result may be obtained by substituting sulphuric acid for bromine
or chlorine in the above process. We thus obtain the sulpho-acids of
anthrakinon, which by being dissolved in and heated with an excess of
caustic alkali are converted into alizarine.
SPECIFICATION filed in pursuance of the conditions of the Letters
Patent, and of an Order of the Lord Chancellor, by the said
Heinrich Caro, Charles Graebe, and Charles Liebermann in the
Great Seal Patent Office on the 13th January 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HEINRICH
CARO, of Mannheim, Grand Duchy of Bade, Chemist, CHARLES
GRAEBE, of Berlin, in the Kingdom of Prussia, Chemist, and CHARLES
LIEBERMANN, of Berlin, Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of June, in the year of
our Lord One thousand eight hundred and sixty-nine, in the thirty-third
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto us, the said Heinrich Caro, Charles Graebe, and Charles Lie-
bermann, Her special license that we, the said Heinrich Caro, Charles
Graebe, and Charles Liebermann, our executors, administrators, and
assigns, or such others as we, the said Heinrich Caro, Charles Graebe, and
Charles Liebermann, our executors, administrators, or assigns, should at
any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN PREPARING COLORING MATTERS," upon the condition
(amongst others) that we, the said Heinrich Caro, Charles Graebe, and
Charles Liebermann, our executors or administrators, by an instrument
in writing under our hands and seals, or under the hand and seal of one
of us, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and

page_text: cause the same to be filed in the Great Seal Patent Office on or
before the Thirteenth day of January One thousand eight hundred and
seventy.
NOW KNOW YE, that we, the said Heinrich Caro, Charles Graebe,
and Charles Liebermann, do hereby declare the nature of our said
Invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement,
that is to say:
This Invention relates to improvements on an Invention granted to
Charles Liebermann and Charles Graebe for improvements in preparing
coloring matters, dated the Eighteenth day of November One thousand
eight hundred and sixty-eight, No. 8850, in which the preparation of
artificial alizarine is based upon the action of caustic alkalies upon bibro-
manthrakinon or bichloranthrakinon. We have now discovered that a
similar result may be obtained by substituting sulphuric acid for
bromine or chlorine in the above process. We thus obtain the sulpho-
acids of anthrakinon, which by being dissolved in and heated with an
excess of caustic alkali are converted into alizarine..
This Invention relates to improvements in the production of coloring
matters. and more especially to improvements in the method of
producing what is known as artificial alizarine from anthracene, a
method of producing which was described in Letters Patent granted to
Charles Liebermann and Charles Graebe, dated Eighteenth December
One thousand eight hundred and sixty-eight, and consisted in the
production of artificial alizarine by converting anthracene into either
bibromanthrakinon or bichloranthrakinon, and then acting upon the
same by means of an alkali and precipitating the alizarine contained in
the alkaline solution by means of an acid.
In the Complete Specification of the aforesaid Letters Patent granted
to Charles, Lichermann and Charles Graebe two different series of
processes are described for obtaining the brominated or chlorinated
derivatives of anthrakinon.
In the first of these processes the anthracene is submitted to the action
of oxidising agents, as is well understood, and the oxidised anthracene
or anthrakinon is then treated with bromine or chlorine.
In the second of these processes the anthracene is first treated with
bromine or chlorine, and subsequently submitted to an oxydising process

page_text: anthrakinon, may be obtained,
In an analogous manner we now employ sulphuric acid as a
substitute for the bromine or chlorine employed in the processes above
referred to, and we thus obtain the sulphuric acid derivatives of
anthrakinon, which we call the sulpho-acids of anthrakinon.
Our Invention is carried into effect by means of either of the two
processes, which we will proceed to describe.
In the one process we proceed as follows:-We take about one part by
weight of anthrakinon and about three parts by weight of sulphuric acid
of about the specific gravity of 1848, and introduce the same into a
retort, which may be made of glass, or of porcelain, or of other material
not easily acted upon by sulphuric acid, and the contents are then to be
heated up to about two hundred and sixty degrees centigrade, and the
temperature is maintained until the mixture is found no longer to contain
any appreciable quantity of unaltered anthrakinon. The completion of this
desired operation may be ascertained or tested by withdrawing a small
portion of the product from time to time and continuing the operation
at the high temperature until such product upon being diluted with
water is found to form a substantially perfect solution, thereby indicating
that the anthrakinon has become either entirely or in greater part
converted into the desired product. The results of this operation are
then allowed to cool and are diluted with water; we then add carbonate
of lime in order to neutralize and remove the excess of sulphuric acid
contained in the solution; the mixture is then filtered, and to the
filtrate carbonate of potash or carbonate of soda, by preference in solution,
is to be added until carbonate of lime is no longer precipitated: the
mixture is then filtered and the clear solution is evaporated to dryness.
by which means the potash or soda salts of what we call the sulpho-acids
of anthrakinon are obtained and which are to be treated in the following
manner-We take about one part by weight of this product and from
two to three parts by weight of solid caustic soda or potash; water may
be added or not, but by preference we add as much water as is necessary
to dissolve the alkali after admixture; we heat the whole in a suitable
vessel, and the heating operation is continued at a temperature of
from about one hundred and eighty degrees to about two hundred and
sixty degrees centigrade for about one hour or until a portion of the
mixture is found upon withdrawing and testing it to give a solution in

page_text: water, which being acidulated with an acid, for example sulphuric
acid, will give a copious precipitate of the coloring matters. The
heating operation having been found to have been continued for a
suflicient time the resulting products are then dissolved in water, and
we either filter or decant the solution of the same, from which we
precipitate the coloring matters or artificial alizarine by means of a
mineral or organic acid, such, for example, as sulphuric or acetic acid.
The precipitated coloring matters thus obtained are collected in a
filter or otherwise, and after having been washed may be employed
for the purposes of dyeing and printing either in the same way as
preparations of madder are now used or otherwise.
In carrying out our other process we proceed as follows:-We take
about one part by weight of anthracene and about four parts by weight
of sulphuric acid of specific gravity of about 1848, and the mixture
being contained in a suitable vessel is heated to a temperature of about
one hundred degrees centigrade, at which temperature it is to be main-
tained for the space of about three hours; the temperature is then to
he raised to about one hundred and fifty degrees centigrade, which
temperature is to be maintained about one hour or until a small
portion of the product when submitted to the subsequent processes
herein-after described is found to produce the desired colouring matters;
we then allow the result obtained by this operation to cool, and dilute
it with water, by preference in the proportion of about three times its
weight. To the solution thus obtained we add for every part of an-
thracene by weight which had been employed in the previous operation
about from two to three parts by weight of peroxide of manganese,
preferring to employ an excess, and we boil the whole strongly for some
time, and in order fully to ensure the desired degree of oxidation the
mixture may be subsequently concentrated and by preference be
evaporated to dryness and the heat he continued until a small portion
of the oxidised product when submitted to the subsequent processes
herein-after described will produce the desired coloring matters.
We
then neutralise and remove the sulphuric acid contained in this mixture
and at the same time precipitate any oxides of manganese which may
be held in solution by adding an excess of caustic lime which we use
by preference in the form of milk of lime, and we add the same until
the mixture has an alkaline reaction. We then filter and add to the
filtrate carbonate of potash or soda until there is no further pre-
cipitation of carbonate of lime. The solution is then filtered and

page_text: evaporated to dryness, and we thus obtain the potash or soda salts of
what we call the sulpho-acids of anthrakinon.
In effecting the conversion of the oxydised products thus obtained
into coloring matters, or into what we call artificial alizarine, we proced
as follows: We take one part by weight of this product and from
two to three parts by weight of solid caustic soda or potash, and
water may be added or not, but by preference we add as much water
as is necessary to dissolve the alkali. After admixture we heat the
whole in a suitable vessel and continue the heating operation at a
temperature from about one hundred and eighty degrees to about two
hundred and sixty degrees centigrade for about one hour, or until a
portion of the mixture is found to give solution in water which upon
acidulation with an acid, for example sulphuric acid, is found to give
a copious precipitate of the coloring matters. The heating operation
having been found to have been continued for a sufficient time
then dissolve the product in water, and either filter or decant the
solution of the same, from which we precipitate the coloring matters
or artificial alizarine by means of a mineral or organic acid, such, for
example, as sulphuric or acetic acid. The precipitated coloring matters
this obtained are collected on a filter or otherwise, and after having
heon washed may be employed for the purposes of dyeing and printing
either in the same way as preparations of madder are now used or other-
wise. Instead of acting upon anthracene by means of sulphuric acid
of the density before mentioned fuming sulphuric acid may be employed.
but we prefer to use the ordinary acid, as before described.
In order to effect the process of oxidation before referred to other
oxidising agents may be used in place of the peroxide of manganese
before mentioned, such, for example, as peroxide of lead, or chromic,
nitric, or other acids capable of effecting the desired oxidation may be
employed. If the oxidizing agent be a soluble one, such, for instance,
as chromic acid, any excess of the oxidizing agent that may have been
employed should be removed or reduced before proceeding with the
subsequent operation. Thus, for example, had chromic acid been used
in excess, sulphurous acid may be passed through the product before
adding the lime. In the case of the employment of nitric acid
the oxidised mixture should be heated until the greater proportion of
The nitric acid has been evaporated, and until the sulphuric acid has
become so concentrated that it commences to volatilise.

page_text: Although we have mentioned the employment of carbonate of lime
and of caustic lime for the purpose of effecting the neutralization of the
sulphuric acid existing in the solution of the products obtained from the
treatment of anthrakinon and from anthracene, as herein-before described,
it will be understood that other bases which will neutralize the acid
and which will not in any way be injurious in any of the subsequent
processes may be substituted for the same.
Having now described our Invention, and methods we employ in
carrying it into effect, we claim,-
Firstly. The manufacture of colouring matters by submitting anthra-
kinon to the action of sulphuric acid so as to obtain soluble compounds
which we have called sulpho-acids of anthrakinon, treating the product
of such operation with an alkali, and precipitating the coloring matters
therefrom by means of an acid, as herein described.
Secondly. The manufacture of coloring matters by submitting an-
thracene to the action of sulphuric acid, oxydising the product thereby
obtained, heating such oxydised product with an alkali, and subsequently
precipitating the coloring matters therefrom by means of an acid, as
herein described.
In witness whereof, 1, the said Heinrich Caro, on behalf of myself
and the said Charles Graebe and Charles Liebermann, have to
this my Specification set my hand and seal, this Twenty-first day
of December One thousand eight hundred and sixty-nine.
HEINRICH CARO. (L.s.)