Improvements in the Manufacture or Production of Dye Stuffs.
Year: 1892

page_text: Date of Application, 4th Oct., 1892
Complete Specification Left, 4th July, 1893-Accepted, 5th Aug., 1893
'PROVISIONAL SPECIFICATION.
[Communicated from abroad by THE FARBENFABRIKEN VORMALS FRIEDRICH
BAYER & Co., of Elberfeld, in the Empire of Germany.]
Improvements in the Manufacture or Production of Dye Stuffs.
I, HENRY EDWARD NEWTON of the Office for Patents, 6 Bream's Buildings,
Chancery Lane in the County of London, Patent Agent, do hereby declare the
nature of this invention to be as follows:-
It is known that the method for producing naphthazarine, which is hitherto in
use, and consists in heating alphadinitronaphthalene (1-5) with concentrated
sulphuric acid at elevated temperatures, from about 200 to 300 degrees centigrade,
with or without the addition of zinc, is very defective, as only small amounts of
the product are obtained in this way. This is shewn, for example, in the Berichte
der Deutschen Chemischen Gesellschaft, volume 11, page 1322, and in the
Specification of the German Letters Patent No. 41518.
My foreign correspondents have now found that alphadinitronapthalene (1-5) is
converted into pure naphthazarine, at ordinary temperature, by treating it, on
proper conditions, in sulphuric solution, with sulphur sesquioxide (S,O,), which
process proceeds very easily, and yields a theoretical amount of the substance
desired. This new method of preparing naphthazarine is of considerable technical
It is very
value, as it is very simple, convenient, and reliable in carrying out.
much superior to the processes hitherto in use.
In order to illustrate the new method, the foregoing example is given, the parts
being by weight:-
10 parts of alphadinitronaphthalene (15), finely pulverised, are stirred into
400 parts of sulphuric acid monohydrate, and, on stirring, a solution of sulphur
sesquioxide, obtained by dissolving 5 parts of sulphur in 50 parts of fuming
sulphuric acid, containing 40 per cent. of anhydride, is added, taking care that the
temperature does not arise above 40 degrees centigrade.
The reaction is completed almost instantly, and the end is distinguishable
when a portion of the sulphuric solution, after pouring into cold water, yields a
splendidly blue liquid containing the intermediate product, which is already
formerly described in the Berichte der Deutschen Chemischen Gesellschaft,
volume 4, page 439.
After pouring the whole liquid into water and filtering off the sulphur pre-
cipitated, the filtrate so obtained is heated to boiling, until the original blue color
has changed into the bluish red which is characteristic of naphthazarine.
The liquid is then allowed to cool, and the naphthazarine, which is in a
chemically pure state, is filtered off, and washed out, until the washings no more
shew an acid reaction.
My foreign correspondents have described, in the foregoing example, a way of
converting alphadinitronapthalene (15) into naphthazarine, by means of the new
process found by them. Of course the process is not restricted to the above pro-
portions, for the latter can be varied; for instance the quantity of sulphuric acid
employed and of sulphur sesquioxide used in the said example, can be increased
or diminished. In place of employing complete sulphur sesquioxide, the solution
of alphadinitrona plithalene in concentrated sulphuric acid, may first be mixed with
fuming sulphuric acid, and then powdered sulphur may be added, the same result
being thus obtained.
The nature of this invention is not altered by such modifications, as it generally

page_text: relates to the conversion of alphadinitronaphthalene into naphthazarine, by means of
sulphur sesquioxide, or sulphur and sulphuric anhydride.
Dated this 4th day of October 1892.
NEWTON & SON,
Agents for the Applicant.
COMPLETE SPECIFICATION..
Improvements in the Manufacture or Production of Dye Stuffs.
I HENRY EDWARD NEWTON of the Office for Patents, 6 Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, 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:-
It is known that the method of producing naphthazarin hitherto employed, which
consists in heating alpha-dinitro-naphthalene (1:5) with concentrated sulphuric
acid, at elevated temperatures, from about 200 to 300 degrees centigrade, with or
without the addition of zinc, is very defective, as only small amounts of the
product are obtained in this way. This is shown, for example, in the Berichte der
Deutschen Chemischen Gesellschaft, volume 11, page 1314, and in the Specification
of the German Letters Patent No. 41,518.
:
My foreign correspondents have now found that alpha-dinitro-naphthalene (1.5)
is converted into pure naphthazarin (even at ordinary temperature) by treating it,
under proper conditions, in sulphuric solution with sulphur sesquioxide (S,O), a
solution of which is obtained by dissolving sulphur in fuming sulphuric acid. This
process proceeds very easily, and yields large amounts of the desired substance.
This new method of preparing naphthazarin is of considerable technical value, as,
in practice, it is very simple, convenient, and reliable. It is very much superior to
the processes hitherto in use for producing naphthazarin.
In order to illustrate the new method, the following example is given, the parts
being by weight.
10 parts of finely pulverized alphadinitro naphthalene (1:5) are stirred into
200 parts of " monohydrated" sulphuric acid, and a solution of sulphur sesqui
oxide, obtained by dissolving 5 parts of sulphur in 50 parts of fuming sulphuric
acid (containing 40 per cent. of anhydride), is then added, constantly stirring, and
taking care that the temperature does not rise above 40 degrees centigrade.
The reaction is almost instantly completed, the end being distinguishable by
the fact that when a portion of the sulphuric solution is poured into cold water, a
splendidly blue coloured liquid is obtained, containing the intermediate product
already described in the Berichte der Deutschen Chemischen Gesellschaft,
volume 4, page 440.
After pouring the whole liquid into water and filtering off the precipitated
sulphur, the resulting filtrate is heated to boiling, until the original blue colour has
changed into the bluish-red which is characteristic of naphthazarin.
The liquid is then allowed to cool, and the naphthazarin, which separates in a
pure state, is filtered off, and washed with cold water, until the washings no longer
show an acid action.
My foreign correspondents have described in the foregoing example, a distinct
way of converting alphadinitronaphthalene (1:5) into naphthazarin by means of
the new process found by them. Of course, the process is not restricted to the
above proportions, as the latter can be varied; for instance, the temperature may
be varied within certain limits (say, from 0 to 100 degrees centigrade); the
quantity of sulphuric acid and sulphur sesquioxide used in the said example can
be increased or diminished; and the strength of the acids employed can also be
varied. In place of previously prepared sulphur sesquioxide, the solution of
alpha dinitronaphthalene in concentrated sulphuric acid, may first be mixed with

page_text: fuming sulphuric acid, and then powdered sulphur may be added, the same result
being thus obtained.
According to the researches of my foreign correspondents, the sulphur can be
replaced by such substances as are capable of giving sulphur sesquioxide, when
they are used together with fuming sulphuric acid or sulphuric anhydride. Amongst
the last said substances, the following can be employed; for instance, hydrogen
sulphide, hydrogen super sulphide (H,S,), sulphur monochloride (S,Cl,), or salts of
thiosulphuric acid. The nature of this invention is not altered by such modifica-
tions, as it relates, in general, to the conversion of alpha dinitro naphthalene into
naphthazarin by means of sulphur sesquioxide, or of sulphur, or the like, in
presence of fuming sulphuric acid, or sulphuric anhydride.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
from abroad, I declare that what I claim is :-
1. The production of naphthazarin by treating alpha dinitro naphthalene (1:5)
in sulphuric solution, with sulphur sesquioxide, or with a solution of sulphur in
fuming sulphuric acid or sulphuric anhydride, or with such substances as are
capable of giving sulphur sesquioxide, when they are employed together with
fuming sulphuric acid or sulphuric anhydride, and subsequently isolating the
resulting naphthazarin in a suitable manner.
Dated this 1st day of July 1893
NEWTON & SON,
Agents for the Applicant.