IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL INDIGO
Year: 1882

page_text: LETTERS PATENT to John Henry Johnson of 47 Lincoln's Inn Fields in the
county of Middlesex Gentleman for an invention of "IMPROVEMENTS IN
THE MANUFACTURE OF ARTIFICIAL INDIGO" A communication from abroad by
the Badische Aniline and Soda Fabric of Mannheim in the Grand Duchy of
Baden in the Empire of Germany
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 16th March 1882.
"
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL INDIGO
a communication from abroad by the Badische Aniline and Soda Fabrik of
Mannheim in the Grand Duchy of Baden in the Empire of Germany
This Invention relating to the manufacture of Artificial Indigo is based upon the
discovery that in the presence of suitable condensing agents orthonitrobenzaldehyde
is readily acted upon by certain compounds containing the methyle-carbonyle
group C. H.-CO such as pyruvic or pyroracemic acid, aldehyde acetone
acetophenone or similar mixed methyle-ketones and analogous compounds-
According to the nature of the condensing agent employed a condensation takes
place resulting either in the direct production of artificial indigo or in the
formation of products which in some instances are capable of being changed into
the said colouring matter-In the presence of Alkaline Condensing Agents the first
named reaction takes place and Artificial Indigo may be thus prepared from ortho-
nitrobenzaldehyde in one operation and by the direct action of the above said
methyle-carbonyle compounds-In the presence of suitable Acid condensing
Agents the last named reaction ensues. For instance the condensation between
orthonitrobenzaldehyde and pyruvic or Pyroracemic Acid in the presence of dry
bydrochloric Acid results in the formation of orthouitrocinnamyle-formic Acid a
product capable of being readily changed into artificial Indigo by the action of
Caustic or of Carbonated Alkalies or of Alkaline Earths.

page_text: As an example of the manner in which this Invention may be appled to the
direct production of Artificial Indigo from orthonitrobenzaldehyde the said
Aldehyde is mixed with pyruvic or pyroracemic Acid and the mixture or solution
thus obtained is then rendered strongly alkaline by the addition of a caustic or of a
Carbonated Alkali or of an Alkaline Earth. The mixture quickly turns blue and 5
after some standing at the ordinary temperature the precipitate of artificial Indigo
thus produced may be collected on a filter washed and dried
As another example Orthonitrobenzaldehyde is mixed with or dissolved in
Acetone and to the mixture or solution thus obtained a diluted aqueous solution of
Caustic Soda is gradually added and the reaction is allowed to proceed at the 1
ordinary temperature until a filtered portion no longer separates out any blue
precipitate upon the addition of Caustic Soda.
In a similar manner orthonitrobenzaldehyde may be treated with Aldehyde or
with the above mentioned Methyle-ketones and analogous compounds
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
15th September 1882.
"
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman " IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL INDIGO
a communication from The Badische Anilin and soda Fabric of Mannheim in the
Grand Duchy of Baden in the Empire of Germany.
This Invention relating to the manufacture of artificial Indigo is based upon the
discovery that in the presence of suitable condensing Agents orthonitrobenzaldehyde
is acted upon by certain compounds containing the methyle-carbonyle groupe
CH, CO such as pyruvic or pyroracemic acid, Aldehyde, Acetone, Acetophenone
or similar mixed methyle-ketones. Practical results have hitherto been obtained by
the employment of the said pyruvic or pyrora cemic acid of Acetic Aldehyde and
of Acetone. According to the nature of the condensing agent employed a con-
densation takes place resulting either in the direct production of Artificial Indigo
or in the formation of products which in some instances are capable of being
changed into the said coloring matter. For instance artificial Indigo may be
prepared from Orthonitrobenzaldehyde in one operation and by the direct action of
the above said Methyle-Carbonyle compounds in the presence of Alkaline con-
densing agents whilst in the presence of dry hydrochloric acid the condensation
between Orthonitrobenzaldehyde and pyruvic or pyrora cemic acid results in the
formation of Ortho-nitro-cinnamyle-farmic Acid a product capable of being changed
into Artificial Indigo by the action of caustic or carbonated Alkalies or of Alkaline
Earths.
The said Alkaline condensing agents which hitherto were found to produce
practical results are caustic and carbonated Alkalies and Alkaline Earths of these

page_text: the most energetic agents are caustic Soda and Caustic Potash. Their action takes
place at an ordinary temperature and requires to be regulated by employing the
said Alkalies in moderate excess and in the state of diluted solutions. The action
of caustic ammonia of the carbonated alkalies and of the Alkaline earths is con-
siderably less energetic and proceeds slowly in the cold but it may be accelerated
by heat or by the employment of a large relative proportion of the same. In
general an energetic action of the above said Alkaline condensing agents
results in the direct production of artificial Indigo whilst by moderating the
reaction as far as possible the condensation of Orthonitrobenzaldehyde with the
aforementioned Methyle-Carbonyle compounds may be arrested at the formation
of intermediate products capable of being changed into Artificial Indigo by a
subsequent treatment with caustic or carbonated Alkalies or with alkaline
earths.
I now proceed to describe in which manner this Invention may be carried into.
effect.
About ten parts by weight of Orthonitro-benzaldehyde are mixed with about
six parts by weight of pyruvic or pyroracemic acid and the said mixture is added
to a solution of about five parts by weight of caustic Soda in about one hundred
parts of water. The strongly alkaline. mixture quickly turns blue and after about
twelve hours standing at the ordinary temperature the precipitate of artificial
Indigo thus produced may be collected on a filter washed and dried.
As an example of the manner in which the condensation between Orthonitro-
benzaldehyde and Acetone may be effected about ten parts by weight of Orthonitro-
benzaldehyde are dissolved in or mixed with about fifteen parts by weight of
acetone and the solution or mixture thus obtained is then gradually mixed with
about one hundred and thirty parts by weight of a diluted caustic soda liquor
containing say about three parts by weight of caustic soda. The said strongly
alkaline mixture is then allowed to stand at an ordinary temperature for about
twelve hours or until the separation of a blue precipitate is complete. The said
precipitate is then collected on a filter and well washed with water in order to
eliminate therefrom free alkali and other soluble compounds. The insoluble blue
residue constitutes the artificial Indigo.
As another example of the manner in which this process may be carried out
about ten parts by weight of Orthonitrobenzaldehyde are dissolved in about thirty
parts by weight of acetone and the solution thus obtained is gradually mixed with
caustic baryta-water until the mixture assumes a very slight alkaline reaction such
as may be indicated by turmeric test-paper. In this stage of the process an
intermediate product is formed which may be obtained in a solid condition by
evaporating the excess of acetone contained in the mixture. The result of the
process is then dissolved in about five hundred parts of water and the solution
thus obtained is then rendered strongly alkaline by adding thereto a caustic or
carbonated alkali or an alkaline earth say for instance a solution of about three
parts by weight of caustic soda in about ten parts of water. The mixture quickly
turns blue and after about twelve hours standing at an ordinary temperature the
precipitate of artificial Indigo may be collected on a filter well washed and dried.
Analogous results may be obtained by employing in the above described process
Acetic Aldehyde in the place of Acetone or by substituting other caustic Alkalies
or alkaline earths for the caustic soda therein named.
As an example of the manner in which the condensation between Orthonitro-
benzaldehyde and pyruvic or pyroracemic acid may be conducted so as to result in
the formation of Orthonitrocinnamyle-formic acid about ten parts by weight of
Orthonitrobenzaldehyde are dissolved in about six parts by weight of pyruvic or
pyroracemic acid by the application of gentle heat and the solution thus obtained
after being cooled down to about ten degrees centigrade is saturated with dry
hydrochloric acid gas and allowed to stand quietly for about three days at an
ordinary temperature when crystals of Orthonitrocinnamyle-formic acid will be
abundantly produced and may then be separated from their mother liquor. In

page_text: order to change the said product into Artificial Indigo about ten parts by weight
of Orthonitrocinnamyle-formic acid are dissolved in a solution of about two parts
and a half by weight of carbonate of Soda in about One hundred parts of water
and then a solution of about three parts by weight of caustic soda in about One
hundred parts of water are added. The alkaline solution quickly turns blue and
after about twelve hours standing at an ordinary temperature the precipitated
Indigo may be collected on a filter well washed and dried.
Having now described the nature of the said Invention and the manner in which
the same may be carried into effect I wish it to be understood that what I consider
to be novel and therefore claim as the Invention secured to me by the hereinbefore
in part recited Letters Patent is :-
First The production of artificial Indigo from Orthonitrobenzaldehyde by the
action of pyruvic or pyroracemic acid Acetone or Acetic Aldehyde in the presence
of Alkaline condensing agents substantially in the manner herein before described.
Secondly-The preparation of Orthonitrocinnamyle formic acid by the action of
pyruvic or pyroracemic acid upon Orthonitrobenzaldehyde in the presence of dry
hydrochloric acid substantially in the manner and for the purpose hereinbefore
described.
Thirdly The conversion of Orthonitrocinnamyle formic acid into artificial
Indigo by the action of caustic or carbonated Alkalies or of Alkaline earths
substantially in the mannner herein before described.
In witness whereof I the said John Henry Johnson have to this my
Specification set my hand and seal this twelfth day of September one
thousand eight hundred and eighty two.