The Production of Dye-stuffs.QUAL MOLECULAR PROPORTIONS OF SAFRANINE T AND BETA
Year: 1895

page_text: Date of Application, 2nd Aug., 1899
Complete Specification Left, 4th May, 1896-Accepted, 6th June, 1896
[Communicated from abroad by THE FARBENFABRIKEN,
BAYER & Co., of Elberfeld, Germany.]
The 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 by the interaction of diazo-safranines and phenols, naphthols, or.
the like, in the presence of caustic soda lye, azo dye-stuffs are obtained, which are
almost insoluble in water, and therefore are of little use for dyeing purposes.
My foreign correspondents have now made the discovery that salts of the said
azo dye-stuffs are produced' which dissolve with readiness in water, on coupling
diazoafranines with phenols, naphthols, or the like, in the presence of caustic soda
lye, taking care that no excess of caustic soda lye be employed, but only such a
quantity as is necessary for neutralizing the excess of hydrochloric acid, if any,
contained in the diazo solution;, and for effecting the combination in the manner
represented, for instance, by the following equation
DYE-STUFF FROM EQUAL MOLECULAR PROPORTIONS OF SAFRANINE T AND
BETA NAPHTHOL.
To
A diazo solution prepared in the usual manner from 3.5 parts of safranine T_is
stirred into 1.5 parts of freshly precipitated beta naphthol mixed with water.
the thus obtained mixture, such a quantity of caustic soda lye is added as is
sufficient for neutralizing the excess of acid used in the diazotisation, and for
effecting the formation of the azo product. The colour of the liquid is thus changed
from greenish-blue into reddish-blue. The mixture is further stirred for some time,

page_text: whereupon the dye-stuff, which separates partially from the liquid, is redissolved
by adding thereto a sufficient quantity of hot water. The so-formed solution is
filtered off, and the dye-stuff is salted out with common salt. The precipitate thus
obtained is filtered, pressed, and dried. It dissolves readily in cold water, and with
great readiness in hot water. It dyes cotton mordanted with tannic acid, or the
like, a bluish-violet.
The preceding example is merely typical.
My foreign correspondents do not limit themselves to the directions given therein,
as these may be varied. For instance, other alkalis may be employed instead of
caustic soda-lye used in the preceding example, and safranine T may be replaced by
phenosafranine or its homologues, or analogues, or by monoalkylated or unsym-
metrical dialkylated safranines, in general, by safranines which contain free amido-
groups, and which are capable of being diazotised. Likewise, other dye stuff
components, that is to say, in general, phenols, amines, amido phenols, may be
substituted for the beta-naphthol used in the preceding example. By such
modifications, the nature of the herein before defined invention is not altered, as it
relates to the production of soluble safranine azo dye-stuffs by acting on diazotised
safranine compounds with dye-stuff components in the presence of alkali, care being
taken that no excess of alkali be employed.
Dated this 2nd day of August 1895.
NEWTON & SON,
Agents for the Applicant.
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 when diazo safranines and phenols, naphthols, or the like,
interact in the presence of caustic soda-lye, azo dye-stuffs are formed which are
almost insoluble in water, and therefore are of little use for dyeing purposes.
My foreign correspondents have now made the discovery that readily soluble
salts of the said azo dye-stuffs are produced on coupling diazo safranines with
phenols, naphthols, or the like, in the presence of caustic alkali, if care be taken
that no excess of caustic alkali be used, but only the quantity necessary to neutralise
the excess of hydrochloric acid, if any, which is contained in the diazo solution,
and for effecting the combination in the manner. represented, for instance, by the
following equation

page_text: The process of producing such soluble safranine azo coloring matters may be
carried out in the following manner. The parts are by weight.
EXAMPLE.
DYE STUFF FROM MOLECULAR PROPORTIONS OF SAFRANINE T AND BETA
NAPHTHOL.
A diazo solution prepared in the usual manner from 3.5 parts of safranine T., is
stirred into 15 parts of freshly precipitated betanaphthol mixed with water, and
sufficient caustic soda lye is added to the mixture to neutralise the excess of acid
used in diazotising, and in effecting the formation of the azo product. The color
of the liquid changes from greenish-blue into reddish-blue. After the mixture has
been stirred for a time, the dye-stuff which partially separates from the liquid is
redissolved by adding a sufficient quantity of hot water. The solution is then
filtered off, and the dye-stuff is salted out with common salt. The precipitate thus
obtained is filtered, pressed, and dried. It readily dissolves in cold water, and with
great readiness in hot water. It dyes cotton mordanted with tannic or the like a
bluish-violet.
The preceding example is merely typical. My foreign correspondents do not
limit themselves to the directions given therein, as these may be varied. For
instance, other alkalies may be used instead of the caustic soda-lye prescribed in
the preceding example, and in place of the safranine T., phenosafranine may be
used, or its homologues or analogues, or monalkylated or unsymmetrical dialkylated
safranines, or, in general terms, safranines containing amido groups capable of
being diazotised. Moreover, other dye-stuff components, that is to say, phenols,
amines, and amido phenols, may be substituted for the beta-naphthol used in the
preceding example. Such modifications do not alter the nature of the hereinbefore-
defined invention, as it relates to the production of soluble safranine azo dye-
stuffs by the interaction of diazotised safranine compounds and dye-stuff components
in the presence of alkali, care being taken that no excess of alkali be used.
Having now particularly described and ascertained the nature of this 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 soluble safranine azo dye-stuffs, the which process consists
in acting on diazotised safranines with dye-stuff components in the presence of a
quantity of caustic alkali sufficient to neutralise the excess of acid used in
diazotising, and in effecting the formation of the azo compound, in the manner
herein before described.
2. In the process described in the foregoing Claim One, on the one hand, the
use of any safranine containing a diazotisable amido group, on the other hand, the
use of the usual dye-stuff components, viz., the amido, hydroxy, and amido-hydroxy
compounds of the benzene or naphthalene series.
Dated this 2nd day of May 1896
NEWTON & SON,
Agents for the Applicant.