IMPROVEMENTS IN THE MANUFACTURE OF COLOURING MATTERS
Year: 1885

page_text: We, Dr CHRISTIAN RUDOLPH, of Höchst, and Dr OSCAR GURKE, of Elberfeld,
both in the Empire of Gerinany, do hereby declare the nature of our invention
for "IMPROVEMENTS IN THE MANUFACTURE OF COLOURING MATTERS," to be as
follows:-
FIRST. PRODUCTION OF NAPHTHALENE-TRISULPHONIC-ACID AND ITS SALTS.
"
The sulphuration of naphthalene to form naphthalene-trisulphonic-acid by the
aid of nearly double the quantity of sulphuric anhydride (preferably dissolved in
sulphuric acid) can be performed at a temperature varying between 80 degrees and
180 degrees centigrade. The treatment of the sulphurated mass consists in
neutralizing it, after dilution with water, by means of slaked lime, filtering it to
free it from the gypsum and producing in the known manner from the filtrate,
with the requisite quantity of soda, the sodium salt of the naphthalene-trisulphonic-
acid which has not bitherto been known.
1
If, in the place of the naphthalene, its mono-sulphonic or disulphonic acids (or
their salts) are to be used, correspondingly less sulphuric anhydride is employed,
the remainder of the process is the same as that above described. Sulphuric mono-
chlorhydrin, sulphuric acid and pyrosulphuric alkalies (pyroschwefelsaure alkalien),
sulphuric acid and metaphosphoric acid, and the like can be used as substitutes for
the sulphuric anhydride in the sulphuration.
The sodium salt of the naphthalene-trisulphonic-acid, obtained in either of the
manners above described, is either used directly for the further working, or it is
previously purified by fractional crystallization from water or by extracting with
alcohol of 80° Tralles. In the purified state, the naphthalene-trisulphonate of
sodium is colourless and very easily soluble in water. Other salts of the 'tri-
sulphonic acid, for instance; the potassium, calcium, strontium, "barium, and
magnesium salts, are likewise easily soluble in water; if the raw sulphuration
inass has been employed for their production, their purification 'is effected in the
same manner as above described' with reference to the preparation of the pure
naphthalene-trisulphonate of sodium!*
47.

page_text: SECOND. PRODUCTION OF THE NAPHTHOL-DISULPHONIC ACID AND ITS SALTS.
In the conversion by heat of naphthalene-trisulphonic-acid into naphthol-
disulphonic-acid with the aid of alkalies, the quantitative proportions of the
substances used, as well as the trial temperature, may vary within wide limits.
Good results are obtained by the process hereinafter described which is merely
given as an example of the manner in which this part of our said invention is
carried into practice; and we wish it understood that we do not confine ourselves
to this process.
Part of the naphthalene-trisulphonate of sodium, with half its weight of caustic
soda and a similar quantity of water, is heated in the oil-bath for several hours
to from 170 degrees to 180 degrees; it is advantageous to work in closed vessels,
in order to prevent any escape of the water and consequent drying of the mass.
The molte mass, when ready, contains a mixture of naphthol-disulphonic-acids,
which, for the production of azo-colouring matters, can be used without further
separation.
If one naphthol-disulphonic acid is to be isolated from the molten mass, this
result is most efficiently accomplished by obtaining it in the form of its acid sodium
salts in the following manner, that is to say-A solution of the molten mass in
water is mixed with a sufficient quantity of hydrochloric acid, and evaporated till
the separation of common salt takes place; after cooling, a large proportion of the
acid sodium salt of the naphthol-disulphonic-acid, which is formed, is separated;
further quantities are obtained by repeated concentration of the mother-liquor.
The raw sodium salt thus obtained is crystallized from water for purification.
Another method for obtaining the naphthol-sulphate of sodium consists in
evaporating to dryness a solution of the molten mass, which is neutralized with
hydrochloric acid, and then extracting with alcohol of. 80 degrees Tralles. The
naphthol-disulphate is soluble in alcohol and can thus be separated from the
common salt.
Our acid differs from the known naphthol-disulphonic acids in the following
points, viz
-
1st. From the so-called "R-hydrochloric acid" of the German Patent No. 3229
by the solubility of the sodium salt in alcohol of 80 degrees Tralles.
2nd. From the so-called "G hydrochloric acid" of the German Patent No. 3229,
by the difference between the azo-colouring matters produced with a-naphthyla-
mine; the "G-hydrochloric acid" yields ponceau-red colouring matter, whilst our
acid yields Bordeaux-red colouring matter.
4
3rd. From the naphthol-disulphonic acid of the German Patent No. 32,291, by
the difference between the azo-colouring matters produced with amidoazobenzol;
Vignon's acid yields red-violet colouring matter, whilst our acid yields ponceau-red
colouring matter.
. 4th. From the naphthol-disulphonic acid of the German Patent No. 20716, by
its behaviour with nitric acid: Seltzer's acid yields dinitro-a-naphthol, whilst our
acid does not.
THIRD. PRODUCTION OF THE COLOURING MATTERS.
The production of the new colouring matters is effected according to the method.
of Griess, the diazo combinations of aromatic amines being caused to act upon an
alkaline solution of our naphthol-disulphonic acid.
Example: 1795 parts of hydrochloric a-naphthylamine are dissolved in twenty.
times the quantity of water mixed with 100 parts of hydrochloric acid of the

page_text: calcined soda, or the equivalent quantity af an alkali, are dissolved in 4000 parts
of water, this solution being cooled and the diazonaphthalene-chloride caused to
flow slowly into the same. After the formation of the colouring matter is effected,
it is separated and purified in the manner generally adopted for azo-colouring
matters.
For the better characterization of the new colouring matters it should be
mentioned that, by the combination of the naphthol-disulphonic acid with aniline
is obtained orange, with xylidine ponceau red, with B-naphthylamine red, with
naphthionic acid crimson-red, with amidoazobenzol red, and with benzidine violet
colouring matters.
Azo-colouring matters are sometimes obtained, according to our invention, by
the combination of the naplíthol-disulphonic acid, obtained as above described, with
the diazo-combinations of the following bases and amido-sulphonic acids, vizt.-
aniline, toluidine, xylidine, cumidine, ethylxylidine, ta- and 6-naphthylamine,
amidoazobenzol and its homologues, benzidine, tolidine, idiamidodixylyl, or the
sulphonic acids of the said bases. -

page_text: The sulphuration of naphtalene to form naphthalenetrisulphonic acid by the
aid of nearly double the quantity of sulphuric anhydride (preferably dissolved in
sulphuric acid) can be performed at temperatures varying between 80 degrees and
180 degrees Centigrade.
Examples: One part of naphthalene is gradually introduced into eight parts of
fuining sulphuric acid (containing 24 per cent of sulphuric anhydride), and this
mixture is heated to 180 degrees and maintained at this temperature for some
hours,
Into six parts of fuming sulphuric acid (containing 40 per cent of anhydride) is
introduced one part of naphthalene, care being taken that the temperature of the
mixture does not rise above 80 degrees, the mixture is then heated upon a water
bath until the anhydride has disappeared.
The treatment of. the sulphurated mass consists in neutralizing it, after dilution
with water, by means of slaked lime, filtering it to free it from the gypsum and
producing in the known manner from the filtrate, with the requisite quantity of
soda, the sodium salt of the naphthalenetrisulphonic acid which has not hitherto
been known.
If, in place of the naphthalene, its monosulphonic or disulphonic acids (or their
salts) are to be used, correspondingly less sulphuric anhydride is employed; the
remainder of the process is the same as that above described. ⚫
Sulphuric monochlorhydrin, sulphuric acid and pyrosulphuric alkalies (pyro-
schwefelsaure alkalien), sulphuric acid and metaphosphoric acid, and the like can
be used as substitutes for the sulphuric anhydride in the sulphuration.
The sodium salt of the naphthalenetrisulphonic acid obtained in either of the
manners above described is either used directly for the further working, or it is
previously purified by fractional crystallization from water, or by extracting with
alcohol of 80° Tralles. In the purified state, the naphthalenetrisulphonate of sodium
is colourless and very easily soluble in water. Other salts of the trisulphonic acid,
for instance, the potassium, calcium, strontium, barium, and magnesium salts, are
likewise easily soluble in water; if the raw sulphurated mass has been employed
for their production, their purification is effected in the same manner as above
described with reference to the preparation of the pure naphthalenetrisulphonate of
sodium.

page_text: If naphthalene is leated with a quantity of sulphuric anhydride (dissolved in
sulphuric acid), which is insufficient for completely converting the hydrocarbon
into trisulphonic acid, to from 80 to 180 degrees, a mixture of disulphonic and
trisulphonic acids is obtained which can be worked to form naphtholdisulphonic
acid in the same manner as herein described for naphthalenetrisulphonic acid.
2. PRODUCTION OF THE NAPHTHOLDISULPHONIC ACID AND ITS SALTS.
In the conversion by heat of naphthalenetrisulphonic acid into naphthol-
disulphonic acid with the aid of alkalies, the quantitative proportions of the
substances used, as well as the trial temperatures, may vary within wide limits.
Good results. are obtained by the process which is hereinafter described merely
as an example of the manner in which this part of our said invention is carried
into practice; and we wish it understood that we do not confine ourselves to this.
process..
.
Part of the naphthalenetrisulphonate of sodium, with half its weight of caustic
soda and a similar quantity of water, is heated in an oil-bath-for several hours.to
from 170 degrees to 180 degrees; it is advantageous to work in closed vessels
in order to prevent any escape of the water and consequent drying of the mass."
The molten mass, when ready, contains a mixture of naphtholdisulphonic acids
which, for the production of. azo-colouring matters, can be used without further
separation.
'
.
If one naphtholdisulphonic acid is to be isolated from the molten mass, this
result is most efficiently accomplished by obtaining it in the form of its acid
sodium salts in the following manner, that is to say:-A solution of the molten
mass in water is mixed with a sufficient quantity of hydrochloric acid and
evaporated till the separation of common salt takes place; after cooling, a large
proportion of the acid sodium salt of the napthol-disulphonic acid which is
formed, is separated; further quantities are obtained by repeated concentration of
the mother-liquor. The raw sodium salt thus obtained is crystallized from water
for purification.
Another method of obtaining the naphtholdisulphonate of sodium consists in
evaporating to dryness a solution of the molten mass, which is neutralized with
hydrochloric acid, and then extracting with alcohol of 80 degrees Tralles. The
naphtholdisulphonate is soluble in alcohol and can thus be separated from the
common salt.
Our acid differs from the known naphtholdisulphonic acids in the following
points, viz:
1st. From the so called "R" acid of the German Patent No. 3229 by the
solubility of the sodium salt in alcohol of 80° Tralles.
2nd. From the so-called "G" acid of the German patent No. 3229 by the
difference between the azo-colouring matters produced with a-naphthylamine:-
the "G" acid yields ponceau-red colouring matter, whilst our acid yields
Bordeaux-red colouring matter.
3rd. From the naphtholdisulphonic acid of the German Patent No. 3291 by the
difference between the azo-colouring matters produced with amidoazobenzol 1
Vignon's acid yields red-violet colouring matter, whilst our acid yields ponceau-
red colouring matter.
4th. From the naphtholdisulphonic acid of the German Patent No. 20716 by
its behaviour with nitric acid, Seltzer's acid yields dinitro-a-naphthol, whilst our
acid does not

page_text: of
Example. 179.5 parts of hydrochloric a-naphthylamine are dissolved in twenty
times the quantity of water mixed with 100 parts" of "hydrochloric acid of the
specific gravity of 1-185, and then converted by the afflux of a solution of 70 parts
of sodium nitrite in three times the quantity of water at 0°, into diazonaphthalene-
chloride. On the other hand, from 350 to 400 parts of naphtholdisulphonate
sodium, or a corresponding quantity of the raw molten mass and 60 parts of
calcined soda, or the equivalent quantity of an alkali, are dissolved in 4000 parts
of water, this solution being cooled and the diazonaphthalenechloride caused to
flow slowly into the same. After the formation of the colouring, matter is effected,
the latter is separated and purified in the manner generally adopted for azo-
colouring matters.
For the better characterization of the new colouring matters, it should be
mentioned that, by the combination of the naphtholdisulphonic acid with aniline,
are obtained orange, with xylidine, ponceau-red, with B-naphthylamine, red, with
naphthionic acid, crimson red, with amidoazobenzol, red, and with benzidine, violet
colouring matters.
Azo-colouring matters are sometimes obtained, according to our invention, by
the combination of the naphtholdisulphonic acid, obtained as above described, with
the diazo combinations of the following bases and amidosulphonic acids; viz aniline,
toluidine, xylidine, cumidine, ethylxylidine, a- and 6-naphthylamine, amidoazo-
benzol and its homologues, benzidine, tolidine, diamidodixylyl, or the sulphonic
acids of the said bases.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is,
First The process of producing naphthalenetrisulphonic acid by heating naph-
thalene or its monosulphonic and disulphonic acids (or their salts) with sulphuric
anhydride or other suitable sulphurating agent.
Second-The process of purifying the naphthalenetrisulphonates by the treatment
of the same with alcohol or by fractional crystallization from water.
Third The process of producing a mixture of naphthalene disulphonic and
trisulphonic acids by heating naphthalene with a quantity of sulphuric anhydride
or other suitable sulphurating agent, insufficient for its complete conversion into
trisulphonic acid.
Fourth The process of producing naphtholdisulphonic acid from the naphtha-
lenetrisulphonic acids (or their salts) produced according to either of the processes
named in the first and second claiming clauses, by heating with alkalies.
1
Fifth The process of producing naphtholdisulphonic acid from the mixture of
naphthalene disulphonic and trisulphonic acids obtained according to the process
named in the third claiming clause, by heating with alkalies.
Sixth The process of producing azo-colouring matters by the combination of
the naphtholdisulphonic acid obtained according to either of the processes named
in the third and fifth claiming clauses, with the diazo-combinations of the
following bases and amidosulphonic acids, viz-aniline, toluidine, xylidine,
cumidine, ethylxylidine, a- and B-naphthylamine, amidoazobenzol and its homo-
logues, benzidine, tolidine, diamidodixylyl, or the sulphonic acids of the said bases.