Improvements in the Reduction of Organic Compounds.
Year: 1896

page_text: Date of Application, 11th Feb., 1896
Complete Specification Left, 17th Feb., 1896-Accepted, 21st Mar., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Reduction of Organic Compounds.
I, CARL KELLNER, of 29 Wassagasse, Vienna IX, Austria, Doctor of
Philosophy, do hereby declare the nature of this invention to be as follows:-
As is well known, reduction processes are of great importance in certain
branches of chemical industry, such as in the manufactare of organic colouring
matters, by the reduction of nitroderivatives of aromatic compounds.
The methods heretofore ordinarily employed to carry out these processes, can be
divided into two groups, namely into those of a chemical nature, and those of an
electrolytical nature. Both have various drawbacks. The chemical methods do
not always give a satisfactory yield, and the purely electrolytical reduction
methods are also not without objection, because with them the substance to be
reduced must either act itself as electrolyte, or be mixed with the electrolyte, in
which case, in a similar manner to the reduction process that is effected by means
of electrolytically generated hydrogen, further undesirable and disturbing reactions
take place which result from the direct action of the current upon the substance to
be reduced.
Now according to this invention, which is designed to obviate the aforesaid
drawbacks, the reduction process is effected in a purely chemical manner with the
aid of an amalgam of an alkaline metal, that has been produced by electrolysis,
the reduction being carried out in such a manner that the electric current
employed in producing the amalgam does not act upon the substance to be reduced.
The formation of the said amalgam is effected side by side with the reduction
process, by the electrolysis of an alkaline salt and the use of a mercúry cathode.
It may be here stated that obviously the gaseous anions generated in the course of
this electrolysis, can be utilized in any suitable manner, and serve as valuable
by-products of the process, but this forms no part of the present invention.
In carrying out this invention, a solution of an alkaline salt is subjected to the
action of an electric current in an electrolytical cell that may be of known type
and provided with a mercury cathode, with the result that the separated alkaline
metal is taken up by the mercury to form the corresponding amalgam. The
amalgam thus produced is then conveyed into a reducing chamber separated from
the electrolytical decomposing cell and wherein it is brought into intimate contact
with the solution of the substance to be reduced, the reduction process being then
effected in the well known way. The mercury, which is regenerated in the
reduction process, can again serve to form amalgam in the electrolytical decom-
posing cell, so that the formation of amalgam will always take place only to the
extent necessary to effect the reduction process.
The alkaline hydrate formed from the alkaline metal of the amalgam in the
course of the reduction process may, according to the chemical nature of the
product of the reduction process, may either be recovered unaltered, or it may
combine with the product of the reduction process to form a salt.
From the foregoing description it will be seen that the essential feature of this
invention consists in that the electrolytical and chemical operations comprised in
the process are effected separately and independently of each other so as to
obviate interfering secondary reactions, for which purpose the electrolytical
splitting up of the alkaline salt (for example sodium chloride, or sodium hydrate)
and formation of an amalgam, is effected by the aid of a mercury cathode in a
chamber separate from that in which the amalgam is used to effect the reduction

page_text: of the desired organic compound. By this means, reduction processes can be
effected not only in alkaline, but also in neutral and in acid solutions, if the
alkaline hydrate produced by the reduction is neutralized, in the one case, by a
suitable addition of acid, or in the other case, is rendered acid by the addition of
an excess of acid to the materials in course of reduction.
The reduction process hereinbefore described is of course not limited in its
application to a determined class of substances, but can be applied in all cases of
reduction where nascent hydrogen can be advantageously used as a reducing
agent.
Thus the process can be employed for the reduction of nitro-benzol, nitrotoluol,
and in general of the nitroderivatives of aromatic hydrocarbons, or of their carbo-
acids or sulpho-acids, and also for the direct production of azo compounds and
hydrazo-compounds by reduction of the corresponding nitro-substances in alkaline
solution.
Similarly the reduction of compounds, such as sugar-acid, belonging to the group
of carbo-hydrates, can be effected in acid solution by means of the process herein-
before described.
Dated this 11th day of Wah 1000
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
Improvements in the Reduction of Organic Compounds.
1, CARL KELLNER, of 29 Wassagasse, Vienna IX, Austria, Doctor of
Philosophy, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
As is well known, reduction processes are of great importance in certain
branches of chemical industry, such as in the manufacture of organic colouring
matters, by the reduction of nitroderivatives of aromatic compounds.
The methods heretofore ordinarily employed to carry out these processes, can be
divided into two groups, namely into those of a chemical nature, and those of an
electrolytical nature. Both have various drawbacks. The chemical methods do
not always give a satisfactory yield, and the purely electrolytical reduction
methods are also not without objection, because with them the substance to be
reduced must either act itself as electrolyte, or at least be mixed with the
electrolyte, in which case, simultaneously with the reduction process that is
effected by means of the electrolytically generated hydrogen, further undesirable
and disturbing reactions take place which result from the direct action of the
current upon the substance to be reduced.
Now according to this invention, which is designed to obviate the aforesaid
drawbacks, the reduction process is effected in a purely chemical manner with the
aid of an amalgam of an alkaline metal, that has been produced by electrolysis,
the reduction being carried out in such a manner that the electric current employed
in producing the amalgam does not act upon the substance to be reduced. The
formation of the said amalgam is effected side by side with the reduction process,
by the electrolysis of an alkaline salt and the use of a mercury cathode. It may
be here stated that obviously the gaseous anions generated in the course of this
electrolysis, can be utilized in any suitable manner, and serve as valuable by-
products of the process, but this forms no part of the present invention.
In carrying out this invention, a solution of an alkaline salt is subjected to the
action of an electric current in an electrolytical cell that may be of known type
and provided with a mercury cathode, with the result that the separated alkaline

page_text: metal is taken up by the mercury to form the corresponding amalgam. The
amalgam thus produced is then conveyed into a reducing chamber separated from
the clectrolytical decomposing cell and wherein it is brought into intimate contact
with the solution of the substance to be reduced, the reduction process being then
effected in the well known way. The mercury, which is regenerated in the
reduction process, can again serve to form amalgam in the electrolytical
decomposing cell, so that the formation of amalgam will always take place only to
the extent necessary to effect the reduction process.
The alkaline hydrate formed from the alkaline metal of the amalgam in the
course of the reduction process may, according to the chemical nature of the
product of the reduction process, may either be recovered unaltered, or it may
combine with the product of the reduction process to form a salt..
From the foregoing description it will be seen that the essential feature of this
invention consists in that the electrolytical and chemical operations comprised in
the process are effected separately and independently of each other so as to obviate
interfering secondary reactions, for which purpose the electrolytical splitting up of
the alkaline salt (for example sodium chloride, or sodium hydrate) used for the
formation of an amalgam, is effected in a chamber separate from that in which the
obtained amalgam is used to effect the reduction of the desired organic compound.
By this means, reduction processes can be effected not only in alkaline, but also in
neutral and in acid solution, if, in the one case, the alkaline hydrate produced by
the reduction is neutralized, by a suitable addition of acid, or in the other case, the
material undergoing the reaction is rendered acid by the addition of an excess of
acid.
The reduction process herein before described is of course not limited in its
application to a determined class of substances, but can be applied in all cases of
reduction where nascent hydrogen can be advantageously used as a reducing
agent.
Thus the process can be employed for the reduction of nitro-benzol, nitrotoluol,
and in general of the nitroderivatives of aromatic hydrocarbons, or of their carbo-
acids or sulpho-acids, and also for the direct production of azo compounds and
hydrazo-compounds by reduction of the corresponding nitro-substances in alkaline
solution.
Similarly the reduction of compounds, such as sugar-acid, belonging to the
group of carbon-hydrates, can be effected in acid solution by means of the process
hereinbefore described.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
A process of reducing organic compounds by combined electrolytical and
chemical operations this process consisting in bringing the said organic compounds
in a neutral, alkaline or acid solution, into intimate contact with an amalgam of an
alkaline metal that has been produced by electrolysis in a chamber separate from
the reducing chamber, as set forth.
وليود
1000
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.