The Manufacture of a New Amidonaphtholdisulpho Acid and Colouring Matters therefrom.
Year: 1893

page_text: Date of Application, 31st Oct., 1893
Complete Specification Left, 30th July, 1894-Accepted, 1st Sept., 1894
PROVISIONAL SPECIFICATION.
[Communicated from abroad by THE FARBENFABRIKEN vormals FRIEDRICH
BAYER & Co., of Elberfeld, in the Empire of Germany.]
The Manufacture of a New Amidonaphtholdisulpho Acid and
Colouring Matters therefrom.
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 by the investigations of Armstrong & Wynne (see Proceedings of
the Chemical Society of the year 1890, on page 129) that by a treatment of
B₁ naphthylamine a3 sulpho acid with fuming sulphuric acid, at a low temperature,
two isomeric ẞ-naphthylamine disulpho acids are formed, which possess the
following composition
TT
My foreign correspondents have found that by a more energetic treatment with
sulphonating agents, a new ẞ naphthylamine trisulpho acid is formed. In order to
produce this ẞ naphthylamine trisulpho acid, either the ẞ, naphthylamine α3
monosulpho acid, or the aforesaid two ẞ naphthylamine disulpho acids, can be
employed. In every case, a ẞ-naphthylaminetrisulpho acid is obtained, which is
represented by the following formula:—
My foreign correspondents have also found, that the last named ẞ-naphthylamine
trisulpho acid, when melted with alkalies, is converted into new valuable amido
naphthol disulpho acid, to which my foreign correspondents ascribe the following
formula

page_text: The production of this amidonaphthol disulpho acid is practically effected in
such a manner that at first the aforesaid ẞ naphthylaminetrisulpho acid is prepared,
(which process is represented by the following first example), and subsequently
this trisulpho acid is transformed into the new amidonaphtholdisulpho acid (which
process is illustrated by the following second example). The parts are by
weight.
CONVERSION OF ẞ NAPHTHYLAMINE a₁ as B. TRISULPHO ACID INTO ẞ₁ AMIDO
a NAPHTHOL a1 B DISULPHO ACID.
50 parts of the sodium salt of the above ẞ naphthylaminetrisulpho acid are
mixed with 100 parts of soda and 50 parts of water. The resulting mixture is
heated at from 160 to 220 degrees centigrade in a closed vessel capable of with-
standing pressure, until a sample taken out and coupled with diazo compounds no
longer shows an increase in the formation of dye. At this stage the melted mass is
acidulated by means of muriatic acid. The new amidonaphtholdisulpho acid, which
crystallises out in fine matted needles, is filtered off and pressed, in order to remove
the mother liquor.
The amidonaphtholdisulpho acid forms salts which readily dissolve, and are salted
out by adding alkaline chloride to their solutions. Dilute acid solutions of the salts
show a weak violet-blue fluorescence, whilst dilute alkaline solutions thereof exhibit
a green fluorescence. The solution of the acid sodium salt assumes a green color on
adding ferric chloride, whilst the addition of chloride of lime produces a yellow color.
The orange yellow diazo compound of the new amidonaphtholdisulpho acid easily
dissolves, and can be salted out by means of common salt; it assumes a violet red
color on the addition of alkalies.
As above mentioned, the said B-naphthylaminetrisulpho acid can also be obtained
from the ẞ, naphthylamine as sulpho acid. In this case, the latter acid is, by a treatment
with sulphonating agents at a low temperature, converted into the disulpho acid, and

page_text: subsequently the mixture is heated, if necessary, after adding fuming sulphuric acid,
until the formation of the trisulpho acid is complete.
The fuming sulphuric acid employed in the first example, can be replaced by other
sulphonating agents (such as sulphuric acid, chlorhydrine, or the like).
The directions given in the second example can be varied; for instance, the
proportions, the degree of dilution, and the temperature, can be altered within certain
limits; the soda used may be replaced by potassa or the like.
The researches of my foreign correspondents have shown, that the above amido-
naphtholdisulpho acid can be used advantageously for the production of dye stuffs
hereinafter defined.
My foreign correspondents have found, that the said amidonaphtholdisulpho acid,
and its salts, are capable of combining with the tetrazo derivatives of "benzidine,
its analogues or homologues," so-called "symmetrical" and "mixed" dye stuffs
being formed which produce, on unmordanted cotton, from greenish-blue, blue, violet,
to brown shades. The resulting shades possess great clearness, and are distinguished
by their capability of further diazotisation, and combination with phenols, amines,
diamines, amidophenols, amidophenolethers of the benzene or naphthalene series,
sulpho or carboxylic acids thereof.
The process for producing the so-called "symmetrical" coloring matters derived
from tetrazotised paradianines, and the aforesaid amidonaphtholdisulpho acid, in
general consists in converting one molecular proportion of "benzidine, its analogues
or homologues," into the tetrazo compound, and subsequently allowing the latter
to act on two molecular proportions of the above amidonaphtholdisulpho acid, or
salts thereof, preferably in an alkaline solution, for instance, in a solution rendered
alkaline by means of sodium carbonate.
This process is illustrated by the following example: The parts are by weight.
COLORING MATTERS FROM ONE MOLECULAR
DIANISIDINE
PROPORTION OF
AND TWO MOLECULAR PROPORTIONS OF THE ABOVE AMIDONAPHTHOL-
DISULPHO ACID.
The tetrazo compound obtained in the known manner from 24.4 parts dianisidine,
is allowed to flow into a solution prepared by dissolving 68.2 parts of the acid
sodium salt of the new amidonaphtholdisulpho acid, rendered alkaline by means of
sodium carbonate, and carefully cooled. The formation of the dye-stuff
immediately takes place, and is complete after about 24 hours. The coloring
matter is isolated by salting out, filtering off, and pressing. It produces on
unmordanted cotton clear blue shades, and possesses the following formula :-

page_text: According to the researches of my foreign correspondents, one molecular
proportion of the new amidonaphtholdisulpho acid, or its salts, can also be
combined with one molecular proportion of the tetrazo derivatives of " benzidine,
its analogues or homologues," intermediate products being thus formed which contain
a free diazo group, and therefore can be coupled with another molecular proportion
of an amine, a diamine, phenol, amido phenol, amidophenol ether of the benzene or
naphthalene series, a sulpho or carboxylic acid thereof. So-called "mixed "
stuffs result in this manner.
dye
Naturally, the same "mixed" dye-stuffs can also be obtained if one molecular
proportion of a tetrazo compound derived from "benzidine, its analogues or
homologues," is first coupled with one molecular proportion of an amine, a diamine,
phenol, amido phenol, amidophenolether of the benzene or naphthalene series, a
sulpho or carboxylic acid thereof, and if the so-formed intermediate products are
subsequently combined with one molecular proportion of the new amidonaphthol-
disulpho acid, or a salt thereof.
The "mixed" coloring matters obtainable in the manners bereinbefore defined,
also possess the capability of dyeing unmordanted cotton, and chiefly yield from
violet to blue and brown shades.
In order to illustrate the production of these "mixed" dye-stuffs, the following
example is given. The parts are by weight.
DYE STUFF
THOL a2
ACID.
FROM EQUIMOLECULAR PROPORTIONS OF BENZIDINE a₁ NAPH-
MONOSULPHO ACID, AND THE NEW AMIDONAPHTHOLDISULPHO
A solution in water of tetrazo diphenyl chloride, obtained in the well known
manner from 18.4 parts of benzidine, is added to an ice-cold solution prepared by
dissolving 24.6 parts of the sodium salt of a, naphthol a, monosulpho acid and
30 parts of sodium acetate. When the formation of the intermediate product is
complete, the resulting mixture is introduced into an ice-cold solution of 341 parts
of the acid sodium salt of the new amidonaphtholdisulpho acid, the latter solution
being previously rendered alkaline by means of sodium carbonate. The formation
of the mixed coloring matter begins at once, and is completed with advantage by
heating. The dye stuff is isolated by salting out, filtering off, pressing and drying.
It yields reddish blue shades on unmordanted cotton, and is represented by the
following formula :—

page_text: paradiamines in use for such purposes, or if the a₁ naphthol a, monosulpho acid
used in the fourth example is replaced by the corresponding quantities of other
dye-stuff components (such as amines, diamines, phenols, amidophenols, amido-
phenolethers of the benzene or naphthalene series, sulpho or carboxylic acids
thereof).
As above mentioned, the shades obtainable by means of the "symmetrical" and
"mixed" dye-stuffs hereinbefore defined, can, by further diazotisation on the fibre,
and combination with the known dye-stuff components, be converted into more
intense and extremely fast shades.
My foreign correspondents mean by the above expression "benzidine, its
analogues or homologues," the following diamines, viz. :-Benzidine, tolidine,
diamidophenyltolyl, diamidodiphenolether, diamidoalkyloxydiphenyl, diamidoalkyl-
oxyphenyltolyl, diamidoazobenzene, diamidoazotoluene, diamidoazoxylene, diamido-
azoxybenzene, diamidoazoxytoluene, diamidostilbene, diamidofluorene, diamido-
naphthalene, diamidocarbazol, diamidodiphenylene oxide, diamidoditoluylene oxide,
paraphenylenediamine, paratoluylene diamine, benzidine sulphone, tolidine sulphone,
diamidophenyltolyl sulphone, diamidodiphenoxyacetic acid, diamidodiphenylene
ketoxine, diamidophenyl benzimidazol, amidobenzene azo a naphthylamine, amido-
tolueneazo a naphthylamine, amidoxylene azo a naphthylamine, amidobenzene azo
paraxylidine, amidotoluene, azo paraxylidine, amidoxylene azo paraxylidine, amido-
benzene azometa or orthoamido paracresolether, amidotoluene azo meta, or ortho
amido paracresol ether, amidoxylene azo meta or ortho amido paracresolether, amido-
benzene azo ẞ ethoxy a naphthylamine, amidotoluene azo ẞ ethoxy a naphthyl-
amine, amidoxylene azo ẞ ethoxy a naphthylamine, the sulpho or carboxylic
derivatives of the said diamido compounds.
Other diamines, or sulpho derivatives thereof, which can be converted into
tetrazo compounds, either directly, or by means of the monoacetyl derivatives, can
also be used in the above process. In place of the mono acetyl derivatives of
diamines, or diamine sulpho acids, the corresponding mononitro amines, or mono-
nitro amine sulpho acids, can be employed, but in this case the first formed nitro
azo products must be reduced in a suitable manner, this reduction being carried out
at the same time, if, in the corresponding mono acetyl amido azo compounds, the
acetyl group is split off.
My foreign correspondents have described in the above third and fourth
examples, some distinct methods of producing a "symmetrical" and "mixed"
dye-stuff of the series hereinbefore defined. Of course they do not limit them-
selves to the directions given, as the latter can be varied, without departing
thereby from the nature of this invention.
· Dated this 31st day of October 1893.
NEWTON & SON,
Agents for the Applicant..
COMPLETE SPECIFICATION.
The Manufacture of a New Amidonaphtholdisulpho Acid and
Colouring Matters therefrom.
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 by the investigations of Armstrong & Wynne (see Proceedings of
the Chemical Society of the year 1890, on page 129) that by a treatment of
beta,-naphthylamine-alpha,-monosulphonic acid with fuming sulphuric acid, at a

page_text: low temperature, two isomeric beta-naphthylamine disulphonic acids are formed,
which respectively possess the following formulæ :-
SO3H
My foreign correspondents have found, that by a more energetic treatment with
sulphonating agents, a new beta-naphthylamine trisulphonic acid is formed. In 5
-order to produce this beta-naphthylamine trisulphonic acid, the beta-naphthyl-
amine-alpha,-mono-sulphonic acid, or either of the aforesaid two beta-naphthyl-
amine-disulphonic acids, can be used. In every case, a beta-naphthylamine
trisulphonic acid is obtained which has the following formula :-
My foreign correspondents have also found that when the last-named beta-
naphthylamine trisulphonic acid is fused with alkalies, it is converted into a new,
valuable amidonaphtholdisulphonic acid; to which my foreign correspondents.
ascribe the following formula :—
The production of this amidonaphtholdisulphonic acid is practically effected in
such a manner, that the aforesaid beta-naphthylaminetrisulphonic acid is prepared
in the first instance (the which process is represented by the following Example A),
this trisulphonic acid being subsequently transformed into the new amidonaphthol-
disulphonic acid (the which process is illustrated by the following Example B).
The parts are by weight.
PRODUCTION OF BETA1-NAPHTHYLAMINE-ALPHA₁ ALPHA3 BETA-TRISULPHONIC
ACID.
50 parts of the acid sodium salt of the aforesaid beta,-naphthylamine alpha, beta-
disulphonic acid, or beta-naphthylamine-alpha-alphas-disulphonic acid (or 50 parts
of a mixture of these two acid sodium salts) are introduced into from 150 to

page_text: 200 parts of fuming sulphuric acid (containing 40 per cent. of anhydride), the
mixture being carefully cooled. After the whole of the acid sodium salt has been
added, the mixture is heated on a water-bath, until a test portion, when diazotised,
and combined with the so-called R-salt, yields a readily soluble orange-red
colouring-matter. When this stage is arrived at, the mass is treated in the usual
way, viz., poured into ice-water, and the liquid neutralised with lime.
filtering off the precipitated calcium sulphate, the filtrate, containing the calcium
salt of the trisulphonic acid, is mixed with sodium carbonate. The precipitated
calcium carbonate is then filtered off, and the filtrate, containing the sodium salt.
of the new beta-naphthylamine-alpha, alpha, beta-trisulphonic acid, is evaporated
to dryness.
After
The salts of this new beta-naphthylamine-alpha, alpha, beta-trisulphonic acid
are distinguished by readily dissolving in water. The acid potassium salt and
sodium salt form needles which dissolve with great readiness; the barium salt is
also readily soluble. Dilute solutions of these acid salts in water, exhibit a bluish-
fluorescence. The corresponding diazo derivative readily dissolves, and may be
salted out from solutions by common salt in gelatinous flakes. The new beta-
naphthylamine trisulphonic acid cannot be coupled with diazobenzene chloride in a
solution acidulated with acetic acid, and containing sodium acetate. The sulphonic
group in the alpha position is split off, when this beta-naphthylamine-alpha, alpha
beta-trisulphonic acid is heated for a prolonged period with dilute mineral acids,
beta-naphthylamine-alphas beta-disulphonic acid being thus formed.
-
CONVERSION OF BETAL-NAPHTHYLAMINE-ALPHA] ALPHA BETA, TRISULPHONIC
ACID INTO AMIDO-NAPHTHOLDISULPHONIC ACID.
50 parts of the sodium salt of the beta-naphthylamine trisulphonic acid obtainable
by the processes hereinbefore defined, are mixed with 100 parts of soda and
50 parts of water, and the mixture is heated at from 160 to 220 degrees centigrade
in a closed vessel capable of withstanding pressure, until, on testing a sample with
diazo compounds, no further increase in the amount of azo dye is to be observed.
At this stage, the fused mass is cooled, and acidulated with muriatic acid. The
acid sodium salt of the new amidonaphtholdisulphonic acid, which then crystallizes
out, forms fine matted needles. It is filtered off and pressed, in order to remove
the mother-liquor.
The amidonaphtholdisulphonic acid forms readily soluble salts, which can be
salted out by adding an alkaline chloride to its solutions. Dilute solutions of the
acid sodium salt shew a violet-blue fluorescence, which turns into green on the
addition of alkalies. Solutions of the acid sodium salt in water assume a green
colour, on adding ferric chloride, whilst the addition of chloride of lime produces
therein a yellow colour. The orange-yellow coloured diazo compound of the new
amidonaphtboldisulphonic acid, which readily dissolves, and can be salted out by
means of common salt, assumes a violet-red colour in contact with alkalies.
The said amidonaphtholdisulphonic acid is probably beta-amido-alpha,-naphthol-
alpha, beta-disulphonic acid.
As above-mentioned, the aforesaid beta-naphthylamine-alpha, alpha, beta-tri-
sulphonic acid, can also be obtained from beta-naphthylamine-alpha-monosulphonic
acid; in this case, the latter acid is converted by treatment with sulphonating
agents, at a low temperature, into the aforesaid disulphonic acids, and the mixture
is subsequently heated, if necessary, after adding fuming sulphuric acid, until the
formation of the trisulphonic acid is completed.
The directions given in the second example can be varied; for instance, the
proportions, the degree of dilution, and the temperature, can be altered within
certain limits; instead of soda, potassa or the like may be used.

page_text: .
The researches of my foreign correspondents have shown, that the above amido-
naphtholdisulphonic acid can be advantageously used for the production of
dye-stuffs hereinafter defined.
My foreign correspondents have found, that the said amidonaphtholdisulphonic
acid and its salts are capable of combining with the tetrazo derivatives of
"benzidine, its analogues or homologues." So-called "symmetrical" and "mixed"
dye-stuffs are thus formed, which produce on unmordanted cotton, shades chiefly
varying from greenish-blue or blue, to violet and brown. The resulting shades
are of great clearness.
The said symmetrical and mixed dye-stuffs are distinguished by the property
that, when fixed on fibres, they can be further diazotised, and combined with the
known dye-stuff components,-amines, phenols, diamines, amidophenols, amido-
phenolethers of the benzene or naphthalene series, sulphonic- or carboxylic acids
thereof.
The process for producing the so-called "symmetrical" colouring-matters derived
from tetrazotised para-diamines and the aforesaid amidonaphtholdisulphonic acid,
in general consists in allowing one molecular proportion of the tetrazo salts of
benzidine, its analogues or homologues," to act on two molecular proportions of
the above amidonaphtholdisulphonic acid, or alkaline salts thereof, preferably in an
alkaline solution, for instance, in a solution rendered alkaline with sodium
carbonate.
This process is illustrated by the following example. The parts are by weight.
COLOURING-MATTER PRODUCED FROM ONE MOLECULAR PROPORTION OF
DIANISIDINE AND TWO MOLECULAR PROPORTIONS OF THE ABOVE
AMIDONAPHTHOLDISULPHONIC ACID.
The tetrazo compound obtained, in the known manner, from 24.4 parts of
dianisidine, is allowed to flow into a carefully cooled solution of 68.2 parts of the
acid sodium salt of the new amidonaphtholdisulphonic acid, rendered alkaline with
sodium carbonate. The formation of the dye-stuff immediately begins, and is
complete after about 24 hours. The colouring-matter is isolated by salting out,
filtering off, and pressing. It produces clear blue shades on unmordanted cotton.
The following formula represents the composition of this dye-stuff.

page_text: also be combined with one molecular proportion of the tetrazo derivatives of
"benzidine, its analogues or homologues," intermediate products being thus formed,
which contain a free diazo group, and, therefore, can be coupled with another
molecular proportion of an amine, a diamine, phenol, amidophenol, amido
phenolether of the benzene or naphthalene series, a sulphonic or carboxylic acid
thereof. So-called "mixed" dye-stuffs are obtained in this manner.
Naturally the same "mixed" dye-stuffs can also be obtained, if one molecular
proportion of a tetrazo compound derived from "benzidine, its analogues or
homologues," is first coupled with one molecular proportion of an amine, a diamine,
phenol, amidophenol, amidophenolether of the benzene or naphthalene series, a
sulphonic or carboxylic acid thereof, and if the intermediate products so formed are
subsequently combined with one molecular proportion of the new amidonaphthol-
disulphonic acid, or an alkaline salt thereof.
The "mixed" colouring-matters obtainable in the manners herein before defined,
are also capable of dyeing unmordanted cotton, chiefly yielding from violet to
blue, and brown shades.
In order to illustrate the production of these "mixed " dye-stuffs, the following
example is given. The parts are by weight.
DYE-STUFF
OBTAINED
FROM
MOLECULAR
PROPORTIONS OF BENZIDINE,
ALPHA-NAPHTHOL-ALPHA,-MONOSULPHONIC ACID, AND THE NEW AMIDO-
NAPHTHOLDISULPHONIC ACID.
A solution in water of tetrazo diphenylchloride obtained in the well-known
manner from 184 parts of benzidine, is added to an ice-cold solution prepared by
dissolving 24-6 parts of the sodium salt of alpha-naphthol-alpha,-monosulphonic
acid, and 30 parts of sodium acetate. When the formation of the intermediate
product is complete, the mixture is introduced into an ice-cold solution containing
34-1 parts of the acid sodium salt of the new amidonaphtholdisulphonic acid,
The formation of the mixed
previously rendered alkaline with sodium carbonate.
colouring-matter begins at once, and is advantageously completed by heating. The
finished dye-stuff is isolated by salting out, filtering off, pressing, and drying. It
yields reddish-blue shades on unmordanted cotton.
This dye-stuff is represented by the following formula :-
The analogous colouring-matters are produced by using, instead of the dianisidine
and benzidine used in the third and fourth examples, corresponding quantities of
other paradiamines in use for such purposes, or instead of the alpha-naphthol-
alpha-monosulphonic acid used in the fourth example, the corresponding quantities
of other dye-stuff components (such as amines, diamines, phenols, amidophenols,
B

page_text: mers of the benzene or naphthalene series, sulphonic or carboxylic
acids thereof).
As above mentioned, the "symmetrical" and "mixed" dye-stuffs obtainable as
herein before defined, can be diazotised when fixed on fibres, and can then be
combined with the known dye-stuff components,-intense and very fast shades being
thus obtained.
My foreign correspondents mean by the above expression, "benzidine, its
analogues or homologues," the following diamines, viz.-Benzidine, tolidine, diamido-
phenyltolyl, diamidodiphenolether, diamidoalkyloxydiphenyl, diamidoalkyloxy-
phenyltolyl, diamidoazobenzene,diamidoazotoluene, diamidoazoxylene, diamidoazoxy-
benzene, diamidoazoxytoluene, diamidostilbene, diamidofluorene, diamidonaphtha-
lene, diamidocarbazol, diamidodiphenylene oxide, diamidoditoluylene oxide, para
phenylene diamine, paratoluylene diamine, benzidine sulphone, tolidine sulphone,
diamidophenyltolyl sulphone, diamidodiphenoxyacetic acid, diamidodiphenylene
ketoxime, diamidophenylbenzimidazol, amidobenzene-azo-alpha-naphthylamine,
amidotoluene-azo-alpha-naphthylamine, amidoxylene-azo-alpha-naphthylamine,
amidobenzene-azo-para-xylidine, amidotoluene-azo-para-xylidine, amidoxylene-azo-
para-xylidine, amidobenzene-azo-meta- or ortho- amido-para-cresolether, amido-
toluene-azo-meta- or ortho- amido-para-cresolether, amidoxylene-azo-meta -or ortho-
amido-para-cresolether, amidobenzene-azo-beta-ethoxy-alpha-naphthylamine, amido-
toluene-azo-beta-ethoxy-alpha-naphthylamine, amidoxylene-azo-beta-ethoxy-alpha-
naphthylamine, the sulphonic or carboxylic derivatives of the said diamido
compounds.
Other diamines, or diamine sulphonic acids of the benzene or naphthalene series,
which can be converted into tetrazo compounds, either directly, or by means
of their monacetyl derivatives, can also be used. The corresponding mononitr-
amines, or mononitramine sulphonic acids, can be used in place of the monacetylated
diamines, or monacetylated diamine sulphonic acids, in which ease the mononitroazo-
products which are first formed, must be reduced, and the amidoazo compounds
again diazotised, while the monacetylamidoazo compounds which are produced on
using monacetylated diamines, are treated in a suitable manner, in order to split off
the acetyl group, and the amido azo compounds so produced are again diazotised,
and further combined with dye-stuff components.
My foreign correspondents have described in the above Examples C and D,
several distinct methods of producing one of the "symmetrical" and one of the
mixed" dye-stuffs hereinbefore defined. Of course, they do not limit themselves
to the directions given, as the latter can be varied, without departing thereby from
the nature of this invention.
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 a new amido-naphthol-disulphonic acid, which is probably
beta, amido-alpha-naphthol-alpha, beta-disulphonic acid, by fusing, with alkalies,
bota-naphthylamine-alpha-alpha,-beta-trisulphonic acid, or salts thereof.
2. The process for producing a new amidonaphthol disulphonic acid, which is
probably beta-amido-alpha,-naphthol-alpha-beta-disulphonic acid, by sulphonating
either beta,-naphthylamine-alpha,-monosulphonic acid, or beta, naphthylamine-
alpha, beta, disulphonic acid, or beta,-naphthylamine-alpha, alphas-disulphonic
acid, or salts thereof, and subsequently melting with alkalies the beta,-naphthyl-
amine-alpha, alpha, beta-trisulphonic acid thus formed, or salts thereof.
3. The production of "symmetrical dye-stuffs, by combining one molecular
proportion of the tetrazo salts of benzidine, its analogues or homologues, with two
molecular proportions of the above-named beta-amido-alpha,-naphthol-alpha, beta
disulphonic acid, or an alkaline salt thereof.
4. The process for producing "mixed" dye-stuffs, which process consists either
in combining one molecular proportion of the tetrazo salts of benzidine, its analogues

page_text: or homologues, with one molecular proportion of the above-named beta-amido-
alpha-naphthol-alpha-beta-disulphonic acid, or an alkaline salt thereof, and one
molecular proportion of another dye-stuff component, or in coupling one molecular
proportion of the tetrazo salts of benzidine, its analogues or homologues, first with
one molecular proportion of a dye-stuff component, and then with one molecular
proportion of the above-named beta,-amido-alpha3-naphthol-alpha, beta-disulphonic
acid, or an alkaline salt thereof.