IMPROVEMENTS IN PREPARING COLORING MATTERS.
Year: 1868

page_text: LETTERS PATENT to Charles Liebermann and Charles Graebe, of
Berlin, in the Kingdom of Prussia, Chemists, for the Invention
of "IMPROVEMENTS IN PREPARING COLORING MATTERS.'
Sealed the 15th June 1869, and dated the 18th December 1868.
PROVISIONAL SPECIFICATION left by the said Charles Liebermann.
and Charles Gracbe at the Office of the Commissioners of Patents,
with their Petition, on the 18th December 1868.
We, CHARLES LIEBERMANN and CHARLES GRAEBE, of Berlin, in the
Kingdom of Prussia, Chemists, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN PREPARING COLORING MATTERS," to be as
follows:-
This Invention has for its object improvements in preparing coloring
matters for dyeing and printing, and for this purpose we take the
substance known by the name anthracene or paranapthalin, which is
formed under the high boiling portions of coal tar, and is prepared and

page_text: purified by distillation and crystallization. From this substance can
be obtained by nitric acid, as is well known to chemists, a compound
of the formula C₁, H, O, (C= 12, O= 16), which is called oxanthracene
or anthrachinon.
==
We prepare the anthrachinon by the following new methods :-
(1.) Anthracene is treated by bi-chromate of potassium and sulphurio
acid or acetic acid at the temperature of boiling water or higher, or
instead of chromate of potassium any other salt of chromic acid can be
employed.
(2.) Antracene is entirely, or for the greatest part, dissolved in acetic
acid heated at 100° to 120° C., and is converted into anthrachinon by
the addition of the necessary quantity of nitric acid.
We mix the anthrachinon thus obtained with bromine, by pressure
in the proportion of one-equivalent of anthracene to four equivalents of
bromine, and heat it to 80-130° C. in a closed vessel. Great quantities]
of hydrobromic acid are produced, which can be collected by leading-it-
into water or an alkaline solution, our new substance of the formula
C₁ H. Br. O, (bibromanthrachinon) remaining in the vessel in a solid
state. The bibromanthrachinon C₁, H, Br, O, can also be prepared in
the following way:-Bromine acting on anthracene at the tempora- 2
ture of the air forms a crystalline mass, which treated with a solution
of caustic potass in alcohol gives a substance of the formula C₁, H. Br.
(tetrabromanthracene), which is changed by oxidating agents into
bibromanthrachinon, C₁, H, Br, O,; or instead of bromine chlorine can
be employed in the same manner for the production of bichloranthra. 2
chinon. On treating the bibromanthrachinon or bichloranthrachinon
with a concentrated solution of caustic potass or soda to 180-260° C. a
blue color is produced by the formation of the potassium or sodium salt
of altzarine. The alkaline mass thus obtained is extracted by water,
and from the violet solution yellow flocks of alizarine are precipitated 3
by an organic or inorganic acid. The alizarine prepared in this artificial
way is perfectly pure and can be employed in all the applications to
which the different preparations of madder are used,

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Liebermann and Charles Graebe in the
Great Seal Patent Office on the 17th June 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, CHARLES
LIEBERMANN and CHARLES GRAEBE, of Berlin, in the Kingdom of
Prussia, Chemists, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of December, in the
year of our Lord One thousand eight hundred and sixty-eight, in the
thirty-second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Charles Liebermann and Charles
Graebe, Her special licence that we, the said Charles Liebermann
and Charles Graebe, our executors, administrators, and assigns, or Büch
others as we, the said Charles Liebermann and Charles Graebe, our
exccutors, administrators, and 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 Charles Liebermann and Charles Graebe, our executors or
administrators, by an instrument in writing under our, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to
be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
NOW KNOW YE, that we, the said Charles Liebermann and Charles
Graebe, 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) :--
The following is the manner in which we prefer to proceed for pre-
paring the anthrakinon or oxanthracene:-We take 1 part of anthracene,
2 parts by weight of bi-chromate of potassium, and from 10 to 15 parts
of concentrated acetic acid, and we heat these substances together in a
vessel, either of glass or clay, to from 100° to 120° C. till nearly all the

page_text: bi-chromate of potassium is dissolved and the liquid has acquired a deep
green color. We then recover the acetic acid not consumed in the reaction
by distillation, and treat the residue with water to remove the chromic
acetate. From the insoluble mass we obtain the anthrakinon in a pure
state by distilling the whole in a retort of glass or iron. In the place
of the acetic acid may be used sulphuric acid diluted with 1 or 2 parts
of water, and in the place of the bi-chromate of potassium any other
chromate or chromic acid may be employed.
Instead of the method just described we in some cases employ the
following:- -We heat anthracene in a vessel of glass or clay with 10
parts of concentrated acetic acid to 100° C. or more, and we add nitric
acid of 18 spec. gr. in small portions till the violent reaction ceases.
After distillation of the acetic acid we purify the residue as before.
We then convert the anthrakinon prepared by one of the methods
above described into bibromanthrakinon. For this purpose we take
-3-parts-of anthrakinon and 5 parts of bromine, and we heat these sub-
stances-to-a-temperature by-preference of 100° C. for ten or twelve
hours, or until nearly the whole of the bromine has disappeared, in a
suitable close vessel, either of glass or glazed iron, which is capable of
sustaining the pressure generated by the reaction. The apparatus is
then allowed to cool; it is opened in order to permit the escape of
hydrobromic acid, which can be recovered by absorption either-in-water-
or in an alkaline solution. We purify the bibromanthrakinon remaining
in the vessel as a solid substance by crystallisation from benzol.
Instead of the method before described for preparing the bibroman-
thrakinon we also employ the following:-We convert first the anthacene
into a bromine forming the tetrabromanthracene, known to chemists by
the investigations of Anderson: Wo take one part of this tetrabroman-
thracene and heat it in a retort of glass or clay with about 5 parts of
nitric acid of 1-3 spec. gr. to 100° C., as long as vapours of bromine are
evolved. We distill the greater portion of the nitric acid, wash the
residue with water, and purify it by crystallisation from benzol. We
thus receive the bibromanthrakinon as before in the form of a yellow
solid mass. We then convert the bribromanthrakinon into alizarine.
For this purpose we take 1 part of bibromanthrakinon, from 2 to 3 parts
of caustic potash or soda, and as much water as is necessary to dissolve
the alkali, and we heat the whole in an open vessel of glass, glazed iron,
or silver to from 180° to -260° C. for one hour, or till the mass has

page_text: acquired a deep blue color. We then dissolve it in water and filter the
violet solution, from which we precipitate the alizarine by an inorganic
or organic acid. We collect the yellow flocks of alizarine thus obtained
on a filter and wash them with water. By these methods we receive
the alizarine in a form in which it can be employed in the same manner
as the different preparations from madder.
In the place of bromine chlorine may be employed, but not so con-
veniently, since the reactions above described are more difficult to
accomplish with chlorine than with bromine.
Having thus described the nature and particulars of our said Inven-
tion, and the manner of performing the same, we would have it under-
stood that we do not confine ourselves to the exact details of the process
herein-before given; but what we claim is, the artificial production of
alizarine by first preparing bibromanthrakinon or bichloranthrakinon
and then converting these substances into alizarinc, as herein described.
In witness whereof, we, the said Charles Grache and Charles
Liebermann, have hereunto set our hands and' seals, this Second
day of June, in the year of our Lord 1869.
CHARLES GRAEBE.
(L.S.)
CHARLES LIEBERMANN. (L.S.)