Improvements in the Manufacture of Dyestuffs.
Year: 1892

page_text: Date of Application, 16th Apr., 1892 ·
Complete Specification Left, 16th Jan., 1893-Accepted, 25th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Dyestuffs.
I, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, do hereby declare the nature of this invention (which has
been communicated to me from abroad by The Badische Anilin & Soda Fabrik,
of Ludwigshafen on the Rhine, in the Empire of Germany,) to be as follows:—
In the year 1887 my foreign correspondents discovered a new series of dyestuffs
to which they gave the name of rhodamines, and the first known members of
this series are protected under Letters Patent No. 15374 of 1887 granted to me.
These dyes have proved very valuable and are widely used in dyeing and printing;
further, this discovery of my foreign correspondents opened up a new field of
research to colour chemists and through developments of this invention several
other new dyes have been discovered. The dyes described in the above mentioned
Letters Patent are tetra-alkylated rhodamines and give bluish shades of red. In
1889 my foreign correspondents patented in Germany di-alkylated rhodamines
(German Patent No. 48731) and showed that they were of a yellower shade of
red than the corresponding rhodamines containing four proportions of alkyl.
More recently my foreign correspondents have discovered that the tetra-alkyl-
rhodamines, under suitable treatment can be partially dealkylated, and the dyes
thus obtained are again of a yellower shade of red than the tetra-alkyl-rhodamines
from which they are obtained (as set forth in the Specification accompanying my
application for Patent No. 14723º¹). It is thus established that, in the rhodamine
series, a diminution in the number of alkyl-groups present tends to the production
of dyes yielding yellower, that is less blue, shades of red.
Now, my foreign correspondents have recognized the fact that the scope of this
law is still wider and that just as less bluish rhodamines can be obtained by
dealkylating that is splitting off alkyl from, the tetra-alkylated rhodamines, so also
bluer rhodamines can be obtained by treating the tetra-alkyl-compounds in such a
way that they take up more alkyl and yield what I call ultra-alkylated products;
and the present invention relates to the discovery of new and rational processes
for the production of these bluer ultra-alkylated dyes of the rhodamine series.
My foreign correspondents have discovered two distinct methods to be practicable
in converting the tetra-alkyl-rhodamines into the bluer dyes; both of which can be
applied generally to all the tetra-alkyl-rhodamines and for the purpose of introducing
any alkyl group.
According to the first method the tetra-alkyl-rhodamine is treated with an
alcohol, and a mineral acid; in the second a tetra-alkyl-rhodamine salt is treated
with an alcohol preferably under pressure at a suitably high temperature.
It is also possible to treat dialkylated and other rhodamines by these processes.
The following examples will serve to illustrate the nature of the invention, but
the details can be varied in many respects.
Example 1. Stir about one part of tetra-ethylrhodamine of the phthalic acid
series (either base or salt) with about two parts of ordinary ethyl-alcohol and to
the mixture add gradually about one and a half parts of concentrated sulphuric
acid. Heat the solution so obtained for about eight hours on the water bath, and
subsequently pour it into about twenty parts of water. Neutralize the sulphuric
5 acid with soda and salt out the dyestuff which separates in a syrupy or pitch-like
form and pour off the solution. Redissolve and again precipitate with salt and
dry at a temperature of about fifty degrees centigrade, when the dye soon becomes
sufficiently hard to be powdered.

page_text: In the colouring matter thus obtained, there is present as a rule more or less
unchanged tetra-ethyl-rbodamine and the colouring matter can be applied in dyeing
and printing either without separating from this or after previous separation or
isolution.
To isolate the bluer ultra-alkylated rhodamine advantage may be taken of its
increased basicity as follows:
Dissolve the mixed product obtained as above described in water and carefully
add just sufficient soda solution to produce an alkaline liquid. Then extract the
mixture with benzene (or a similar suitable solvent); the unchanged tetra-ethyl-
rhodamine base is taken up, while the ultra-alkylated product on account of its
greater basic power remains almost completely in solution. Precipitate with
common salt and work up as usual.
Instead of soda, sodium acetate or tartrate and other bodies which act similarly
as weak alkalies can be used.
The colouring matter so obtained yields a powder with a bronze-like or green
metallic sheen, it is distinguished by the bluer shades which it imparts to fibre,
by its greater affinity for both animal and vegetable fibre and by its greater basic
power.
Example 2. Stir about one part of finely powdered tetra methyl rhodamine of
the succinic acid series (hereinafter called tetramethyl rhodamine S) into about
five parts of methyl-alcohol and saturate the mixture in the cold with dry hydro-
chloric acid gas.
Allow the mixture to stand for a day or two, then drive off
the greater part of the hydrochloric acid and the methyl-alcohol on the water-bath.
Dissolve the residue in hot water, filter and precipitate the colouring matter with
cominon salt and zinc-chloride.
The reaction can also be effected at a higher temperature, for this purpose heat
the mixture of tetra-methyl-rhodamine S and methyl-alcohol on the water bath
and pass in hydrochloric acid gas for several hours, until no further change of
the colour towards blue can be noticed.
Any unchanged tetra-methyl-rhodamine S can if desired be extracted from the
product by taking advantage of the difference in the solubility in dilute hydro-
chloric acid; for this purpose dissolve the product in water and to the dilute
solution add a little hydrochloric acid, the unchanged tetra-methyl-rhodamine S is
precipitated or crystallizes out on standing in the cold before the ultra-alkylated
product.
The dyestuff thus obtained differs from tetra-methyl rhodamine S in the same
way as the ultra-alkylated product obtained as described under Example 1 differs
from tetra-ethyl-rhodamine. It is a green shining or glittering powder more
readily soluble in dilute hydrochloric acid than the tetra-methyl-rhodamine S ;
unlike this parent rhodamine the ultra-alkylated product possesses considerable
affinity to wool and silk and the affinity to unmordanted cotton is also considerably
increased.
In the above example instead of passing a stream of gaseous hydrochloric acid
through the mixture of rhodamine S and alcohol, strong fuming hydrochloric acid
can be added.
The above examples are merely given as types; the tetra-ethyl-rhodamine can
be substituted for the tetra-methyl-rhodamine S and vice-versa, also other alkyl
rhodamines as hereinbefore mentioned can be treated in a similar way to give
analogous results. Moreover ethyl or methyl alcohols can be used and other
monohydric alcohols such as iso-amyl-alcohol and benzyl-alcohol can be similarly
applied. The various ultra-alkylated products from any one tetra-alkyl-compound
resemble one another closely and are all of a bluer shade than the parent
substance.
Besides monohydric alcohols others can be used in the same way as illustrated
in the next example which describes the use of glycerol.
Example 3. Dissolve about one part of tetra-ethyl rhodamine in about ten parts
of glycerol at about 100 degrees centigrade and pass dry hydrochloric acid gas

page_text: through the solution. Keep the solution hot in a water-bath and take tests from
time to time. Continue the treatment for several hours until no further change of
colour towards blue can be noticed in the tests. Pour the whole into water,
neutralize with soda, precipitate the dye with salt and purify if necessary by re-
dissolving and reprecipitating. The ultra-alkylated product thus obtained closely
resembles the corresponding ultra ethylated product described above under
Example 1.
The foregoing three examples illustrate the first method of ultra alkylating
tetra-alkyl rhodamine; in the following examples, typical instances are given of
the production of the bluer products by treating a tetra-alkyl-rhodamine salt with
the alcohol selected, at a high temperature.
Example 4. Mix together about one part of the hydrochlorate of tetra-methyl-
rhodamine S and about three parts of methyl alcohol and heat the mixture in an
autoclave, that is to say in a closed vessel capable of withstanding pressure, for
about eight hours at a temperature of about one hundred and fifty to one hundred
and sixty degrees centigrade. Subsequently distil off the excess of methyl-alcohol
with steam, filter the hot aqueous solution of colouring matter and precipitate with
salt. The product can be used as it is or it may first be freed from any
unchanged tetra-methyl-rhodamine S as hereinbefore described.
Example 5. Heat together about one part of the sulphate of tetra-ethyl-
rhodamine (phthalic acid) and five parts of ethyl-alcohol in an autoclave for about
twelve hours at a temperature of about one hundred and seventy degrees centigrade.
Distil off the alcohol, dissolve in water and work up as already described under
Example 1 with or without separating any unchanged tetra-alkyl-rhodamine.
In the same way the analogous salts of other alkyl-rhodamines can be treated
and other alcohols can be employed instead of methyl- and ethyl-alcohol.
Dated this 16th day of April 1809
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Dyestuffs.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of
Middlesex Gentleman do hereby declare the nature of this invention (which has
been communicated to me from abroad by The Badische Anilin and Soda Fabrik of
Ludwigshafen on the Rhine in the Empire of Germany) and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
In the year 1887 my foreign correspondents discovered a new series of dyestuffs to
which they gave the name of rhodamines, and the first known members of this series
are protected under Letters Patent No. 15374 of 1887 granted to me. These dyestuffs
have proved very valuable and are widely used in dyeing and printing; further this
discovery of my foreign correspondents opened up a new field of research to colour-
chemists and through developments of their invention several other new dyes have
been discovered. The dyes described in the Specification of the aforesaid Letters
Patent are tetra-alkylated rhodamines and give blueish shades of red. In 1889 my
foreign correspondents patented in Germany dialkylated rhodamines (German
Patent No. 48731) and shewed that they were of a shade of red yellower than that
of the corresponding rhodamines containing four proportions of alkyl. More
recently my foreign correspondents have discovered that the tetra-alkyl-rhodamines,
under suitable treatment can be partially dealkylated, and the dyes thus obtained
are of a shade of red still yellower than that of the tetra-alkyl-rhodamines from
which they are obtained (as set forth in the Specification of Letters Patent
No. 14723). It is thus established that, in the rhodamine series a diminution in

page_text: the number of alkyl- groups present tends to the production of dyes yielding
correspondingly yellower (that is less bluish) shades of red.
Now my foreign correspondents have recognized the fact that the scope of this
law is still wider and that just as less bluish rhodamines can be obtained by
dealkylating, that is splitting off alkyl from, the tetra alkylated rhodamines, so also
bluer rhodamines can be obtained by treating the tetra-alkyl- compounds in such a
way that they take up more alkyl and yield what I call ultra-alkylated products.
These appear chemically to be ethers or esters of the rhodamines, containing the
alkyl group attached to carboxyl. The present invention relates to the discovery
of new and rational processes for the production of these bluer ultra alkylated
rhodamine dyes.
My foreign correspondents have discovered two distinct methods to be practicable
in converting the tetra-alkyl-rhodamines into the bluer dyes; both of which can be
applied generally to all the tetra-alkyl-rhodamines of the phthalic and succinic
series for the purpose of introducing any alkyl- group.
According to the first method the tetra-alkyl-rhodamine is treated with an
alcohol and a mineral acid; and according to the second method a tetra-alkyl-
rhodamine salt is treated with an alcohol at a suitably high temperature under
pressure if necessary.
The following examples will serve to illustrate the nature of the invention and
the manner in which it can be carried into practical effect. but the details can be
varied in many respects. The parts are by weight.
Example 1. Stir about one part of tetra-ethyl-rhodamine of the phthalic acid
series (either base or salt) with about two parts of ordinary ethyl-alcohol and add
gradually to the mixture about one and a half parts of concentrated sulphuric acid.
Heat the solution so obtained for about eight hours on the water bath and
subsequently pour it into about twenty parts of water. Neutralize the sulphuric
acid with soda and salt out the dyestuff which separates in a syrupy or pitch-like
condition and pour off the solution. Redissolve and again precipitate with salt
and dry at a temperature of about fifty degrees centigrade, when the dye soon
becomes sufficiently hard to be powdered.
As a rule there is present in the colouring matter thus obtained more or less
unchanged tetra-ethyl-rhodamine and the colouring matter can be applied in dyeing
and printing either without separating this, or after separation or isolation has been
effected.
To isolate the bluer ultra-alkylated rhodamine advantage may be taken of its
increased basicity as follows:-
Dissolve the mixed product obtained as above described in water and carefully
add just sufficient soda-solution to produce an alkaline liquid. Then extract the
mixture with benzene (or a similar suitable solvent); the unchanged tetra-ethyl-
rhodamine base is taken up, while the ultra-alkylated product on account of its
greater basic power remains almost completely in solution. Precipitate with
common salt and work up as usual.
Instead of soda, sodium acetate or tartrate and other bodies which act similarly
to weak alkalies, can be used.
The colouring matter so obtained yields a powder with a bronze-like or green
metallic sheen; it is distinguished by the bluer shades which it imparts to fibre ;
by its greater affinity for both animal and vegetable fibre and by its greater basic
power.
Example 2. Stir about one part of finely powdered tetramethyl-rhodamine of the
succinic acid series (hereinafter called tetra-methyl-rhodamine S) into about five
parts of methyl-alcohol and saturate the mixture in the cold with dry hydrochloric
acid gas.
Allow the mixture to stand for a day or two, and then on the water
bath drive off the greater part of the hydrochloric acid and the methyl-alcohol.
Dissolve the residue in hot water, filter, and precipitate, the colouring matter with
common salt and zinc-chloride.
The reaction can also be effected at a higher temperature. For this purpose

page_text: heat the mixture of tetra-methyl-rhodamine S and methyl-alcohol on the water-bath
and pass in hydrochloric acid gas for several hours, until no further change of the
colour towards blue can be noticed.
Any unchanged tetra-methyl-rhodamine S can if desired be extracted from the
product by taking advantage of the difference in the solubility in dilute hydro-
chloric acid. For this purpose dissolve the product in water and to the dilute
solution add a little hydrochloric acid. On standing in the cold the unchanged
tetra-methyl-rhodamine S is precipitated or crystallizes out before the ultra-
alkylated product.
The dyestuff thus obtained differs from tetra-methyl-rhodamine S in the same
way as the ultra alkylated product obtained as described under Example 1 differs
from tetra-ethyl-rhodamine. It is a green shining or glittering powder more
readily soluble in dilute hydrochloric acid than is the tetra-methyl-rhodamine S.
Unlike this parent rhodamine the ultra-alkylated product possesses considerable
affinity for wool and silk and the affinity for unmordanted cotton is also considerably
increased.
In the above example instead of passing a stream of gaseous hydrochloric acid
through the mixture of rhodamine $ and alcohol, strong fuming hydrochloric acid
can be added.
The above examples are merely given as types, the tetra-ethyl-rhodamine can be
substituted for the tetra-methyl-rhodamine S and vice versa, also other tetra-alkyl-
rhodamines of the phthalic and succinic series as hereinbefore mentioned can be
treated in a similar way and analogous results be obtained. Moreover ethyl- or
methyl-alcohols can be used and other monohydric alcohols, such as iso-amyl-
alcohol and benzyl-alcohol can be similarly applied. The various ultra-alkylated
products from any one tetra-alkyl- compound resemble each other closely and are
all of a shade which is bluer than is that of the parent substance.
In place of monohydric alcohols other alcohols can be used in the same way as
illustrated in the next example which describes the use of glycerol.
Example 3. Dissolve about one part of tetra-ethyl-rhodamine in about ten parts
of glycerol at about 100 degrees centigrade and pass dry hydrochloric acid gas
through the solution. Keep the solution hot in a water-bath and take tests from
time to time. Continue the treatment for several hours until no further change of
colour towards blue can be noticed in the tests. Pour the whole into water,
neutralize with soda, precipitate the dye with salt and purify, if necessary, by
redissolving and reprecipitating.
The ultra-alkylated product thus obtained closely resembles the corresponding
ultra-alkylated product described above under Example 1.
The foregoing three examples illustrate the first method of ultra alkylating tetra-
alkyl-rhodamine. In the following examples typical instances are given of the
production of the bluer products by treating a tetra-alkyl-rhodamine salt with the
alcohol selected at a high temperature.
Example 4. Mix together about one part of the hydro-chlorate of tetra-methyl-
rhodamine S and about three parts of methyl alcohol and heat the mixture in an
autoclave (that is to say in a closed vessel capable of withstanding pressure) for
about eight hours at a temperature of about one hundred and fifty to one hundred
and sixty degrees centigrade. Subsequently distil off the excess of methyl-alcohol
with steam, filter the hot aqueous solution of colouring matter and precipitate with
salt. The product can be used in the condition in which it is precipitated or it may
first be freed from any unchanged tetra-methyl-rhodamine S as hereinbefore
described.
Example 5. Heat together about one part of the sulphate of tetra-ethyl-rhodamine
(phthalic acid) and five parts of ethyl-alcohol in an autoclave for about twelve
hours at a temperature of about one hundred and seventy degrees centigrade.
Distil off the alcohol, dissolve in water and work up as already described under
Example 1 with or without separating any unchanged tetra-alkyl-rhodamine.
In the same way the analogous salts of other tetra alkyl rhodamines of the

page_text: phthalic and succinic series can be treated and other alcohols can be employed
instead of methyl- and ethyl-alcohol.
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 :-
(1). The manufacture of what I have termed ultra-alkylated-rhodamine dyestuffs
by treating a tetra-alkyl-rhodamine of the phthalic or succinic series with an alcohol
and a mineral acid substantially as hereinbefore described.
(2). The manufacture of what I have termed ultra-alkylated-rhodamines by
treating a salt of a tetra-alkyl-rhodamine of the phthalic or succinic series with an
alcohol at an elevated temperature and if necessary under pressure all substantially
as hereinbefore described.
(3). The manufacture of what I have termed ultra-alkylated-rhodamines from
the materials set forth and substantially in the manners hereinbefore severally
described under the foregoing examples.
Dated this 16th day of January 1893.