Allied Colouring Matters.
Year: 1888

page_text: Date of Application, 16th July, 1888
Complete Specification Left, 16th Apr., 1889-Accepted, 18th May, 1889
Allied Colouring Matters.
I JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention which has been com-
municated to me from abroad by the Badische Anilin and Soda Fabrik of
Ludwigshafen on the Rhine in the Empire of Germany to he as follows :--
This Invention is based upon the discovery that sulphuretted derivatives of para-
amidodimethylanilin are formed by submitting Methylene-red to the action of
alkalies, or by preference, by treating para-amidodimethylanilin with oxydising
agents and thiosulphuric acid. Analogous products are formed by an analogous
treatment of para-phenylenediamine itself and of its alkalysed derivatives other than
the said para-amidodimethylanilin.
Amongst the above mentioned sulphuretted derivatives my foreign correspondents
have discovered a remarkable compound possessing acid properties well crystallised
and endowed with reacting powers analogous to those of para-amidodimethylanilin.
Its composition corresponds to the formula C, H, N₂ S: SO, H.
My foreign correspondents have found that by submitting equal molecules of the
said acid compound and of dimethylanilin, in neutral aqueous solution, to the action
of oxydising bodies, say for instance solutions of soluble chromates, a green crystalline
Indamine is formed almost insoluble in water and possessing a composition corre-
sponding to the formula C, H, N₂ S₂ O₂ + ½ aq. If now the said Indamine be
heated with a solution of chloride of zinc it becomes transformed into methylene
blue. A similar change is effected by sulphate of copper or other cupric salts.
Colouring matters allied to methylene-blue are obtained by the employment of
anilin orthotoluidin and of the secondary and tertiary alkyl-derivatives thereof in the
place of dimethylanilin in the before described reactions.
The following is an example of the manner in which this Invention may be carried
into effect for the purpose of producing methylene blue.

page_text: About six parts by weight of Dimethylanilin are converted into hydrochlorate of
nitroso-dimethylanilin in the well known manner. The nitroso-compound is then
submitted to the reducing action of zinc-dust in order to produce a solution of hydro-
chlorate of para amido-dimethylanilin, which is afterwards to be neutralized, if
necessary by the addition of an alkali or otherwise. There are then added about
sixteen parts by weight of sulphate of alumina and about thirteen parts by weight of
thiosulphate of sodium (hyposulphite of soda) and a solution of about five parts by
weight of bichromate of potash is quickly run in.. At this stage of the process the
formation of the hereinbefore mentioned acid sulphuretted compound takes place.
A solution of about six parts by weight of dimethylanilin in the requisite amount of
dilute hydrochloric acid and, shortly afterwards, a solution of about fourteen parts by
weight of bichromate of potash are then added under constant agitation when a
precipitate will be formed chiefly consisting of the above named green crystalline
Indamine. In order to transform the same into Methylene-blue about seventy five
parts by weight of a solution of chloride of zinc of about 1.5 specific gravity are
added and the mixture thus obtained is boiled for say about half an hour, when after
cooling the methylene-blue thus formed will separate out in a crystalline condition
and may then be filtered and purified, if necessary, by repeated solution in water and
precipitation by means of chloride of sodium or otherwise.
Dated this 16th day of July 1888.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C.,
Agents.

page_text: Allied Colouring Matters.
I JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex,
Gentleman do hereby declare the nature of this Invention (which has been communi-
cated 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 :-
This Invention is based upon the discovery that sulphuretted derivatives of para-
amido-dimethylaniline are formed by submitting Methylene-Red to the action of
alkalies, or by preference, by treating para-amidodimethylaniline with oxidising
agents and thiosulphuric acid. Analogous products are formed by an analogous
treatment of para-phenylene-diamine itself and of its alkylised derivatives other than
the said para-amidodimethylaniline.
Amongst the above mentioned sulphuretted derivatives my foreign correspondents
have discovered a remarkable compound, possessing acid properties, well crystallised
and endowed with reacting powers analogous to those of para-amidodimethylaniline.
Its composition corresponds to the formula: Ca H₁ N, S SO, H.
Now my foreign correspondents have found, that by submitting equal molecules of
the said acid compound and of dimethylaniline in neutral aqueous solution to the
action of oxidising bodies-say for instance solutions of soluble chromates--a green
crystalline Indamine is formed, almost insoluble in water and possessing a composition
corresponding to the formula: C₁ H₁, N3 S, O₂ + ag.
If now the said Indamine be heated with a solution of chloride of zinc, it becomes
transformed into methyleneblue. A similar change is effected by sulphate of copper
or other cupric salts.
Colouring matters allied to methylenebiue are obtained by the employment of
aniline, orthotoluidine and of the secondary and tertiary alkyl-derivatives thereof in
the place of dimethylaniline in the before described reactions."
I. The following is an example of the manner in which this Invention may be
carried into effect for the purpose of producing methylene-blue.
About six parts by weight of Dimethylaniline are dissolved in about eighteen
parts by weight of hydrochloric acid of about 1.16 specific gravity, and then a
solution of about three and eight tenths parts by weight of nitrite of soda in about
six parts by weight of water is gradually added. The hydrochlorate of nitroso-
dimethylaniline, thus produced in the well known manner, is then submitted to the
reducing action of zinc-dust say, for instance, by adding first about thirty parts by
weight of hydrochloric acid of about 116 specific gravity and then-(in small
portions at a time)-about ten parts by weight of zinc-dust, as is well understood by
Chemists. The solution of hydrochlorate of para-amido-dimethylaniline thus obtained
(as is well known) is afterwards diluted with about two hundred and fifty parts by
weight of water, and then the uncombined hydrochloric acid (if any) contained in the

page_text: said solution is neutralised by the addition of an alkali. There are then added about
sixteen parts by weight of sulphate of alumina and about thirteen parts by weight of
thiosulphate of sodium (hyposulphite of soda) and immediately afterwards a solution
of about five parts by weight of bichromate of potash in about sixty parts by weight
of water is quickly run in. At this stage of the process the formation of the hereinbefore-
mentioned acid sulphuretted compound (possessing the formula: C, H₁ N, S SO, H)
takes place. Without previous separation of this intermediate compound, a solution
of about six parts by weight of dimethylaniline in the requisite amount of dilute
hydrochloric acid (say about six parts by weight of hydrochloric acid of about
1-16 specific gravity diluted with about six parts by weight of water) and, shortly
afterwards, a solution of about fourteen parts by weight of bichromate of potash in
about one hundred and sixty parts by weight of water are then added under constant
‘agitation, when a precipitate will be formed chiefly consisting of the above-named
green crystalline Indamine (possessing the formula: C1, H1, N3 S, O3+ aq. in its
pure and air-dried condition). In order to transform the same into Methylene-
blue about fifty parts by weight of a solution of chloride of zinc of about
15 specific gravity are added, and the mixture thus obtained is boiled for say
about half an hour, when, after cooling, the methylene-blue thus formed will
separate out in a crystalline condition and may then be filtered and purified, if
necessary, by repeated solution in water and precipitation by means of chloride of
sodium.
In the second stage of the above described process, which relates to the joint
oxydation of the acid sulphuretted compound and of dimethylaniline, the proportion
of the oxidizing body therein specified exceeds by about one-third the precise
amount required for the production of the above named sulphuretted Indamine. If
this excess of oxidizing agent were not added at this stage of the process, the
subsequent treatment of the said Indamine (described in the final stage of the
process) would yield a mixture of methyleneblue and leukocompounds, which latter
would then, at the conclusion of the process, have to be oxidized in order to produce
the full yield of methyleneblue. It is therefore convenient to effect the conversion of
the Indamine into Methylene-blue in the presence of the required amount of oxidizing
agent substantially in the manner specified in the above example.
In the above described process the sulphate of alumina may be dispensed with
and as much hydrochloric, sulphuric or acetic acid be used as will be required to
liberate the thio-sulphuric acid from the thio-sulphate of sodium employed.
II. The following is an example of the manner in which a colouring matter
allied to methylene-blue may be produced by substituting diethylaniline for dimethyl-
aniline in the first stage of the above described process, which terminates in the
production of the hereinbefore-named acid sulphuretted compound (possessing the
formula: C H₁₁ N, S SO, H). Thus a homologue of the said compound will be
produced, the composition of which corresponds to the formula: C₁o H₁, N, S SO, H.
In order to produce the said homologous compound, the above named six parts by
weight of dimethylaniline are replaced by the equivalent amount of diethylaniline-
say, by about seven and four tenths parts by weight of diethylaniline-and then the
same are converted first into nitroso-diethylaniline and afterwards into para-amido-
diethylaniline, substantially in the manner hereinbefore described viz. by the
successive treatment with nitrite of soda and zinc dust. The solution of hydro-
chlorate of para-amidodiethylaniline thus obtained is then further treated with
thiosulphate of sodium (with or without the aid of sulphate of alumina as above set
forth) and bichromate of potash is immediately afterwards added substantially in
the manner hereinbefore described.
15
:
Thus the above mentioned sulphuretted compound (possessing the formula
C10 H₁ N S SO, H) will be formed, which upon being submitted to a joint
oxidation with about six parts by weight of dimethylaniline, in the manner herein-
before described, will be converted into a green Indamine, nearly insoluble in
water (and possessing in its dry state, a composition corresponding to the formula :-
C. H. N. S.0).
:―

page_text: If now this compound be further treated with a solution of chloride of zinc at an
elevated temperature, substantially in the manner hereinbefore described, it will be
transformed into a homologue of methylene blue, possessing (in the state of its
hydrochlorate) a composition represented by the formula: C₁s H, N, S Cl. The
properties of this coloring matter are very similar to those of methylene blue,
18
Analogous results are obtained by employing methylethylaniline in lieu of
diethylaniline in the above described process.
III. Colouring matters allied to methylene blue are likewise obtained by using
aniline, orthotoluidine, methylethylaniline or diethylaniline in lieu of dimethyl-
aniline in the second stage of the above described processes, which terminates in
the production of the green sulphuretted Indamines therein named (resulting from
the joint oxidation of dimethylaniline and of the above mentioned sulphuretted
compounds).
Thus, by substituting in the above described first example, (which relates to the
production of methylene blue) for the six parts by weight of dimethylaniline
therein specified in the second stage of the process, the equivalent amount of any
of the above named amines, and operating substantially in the manner therein
described, the joint oxidation of the acid sulphuretted compound C H₁₁ N, S SO, H
(produced in the first stage of the process) and of about four and six tenths parts
by weight of aniline, or of about five and three tenths parts by weight of ortho-
toluidine or of about six and seven tenths parts by weight of methylethylaniline
or about seven and four tenths parts by weight of diethylaniline will result in the
production of sulphuretted Indamines analogous, in respect of both their composition
and chemical. properties, to the green crystalline Indamine hereinbefore mentioned
in the first example.
In a similar manner the substitution, for the six parts by weight of dimethyl-
aniline specified in the above described second example (which relates to the
production of homologues of methylene blue), of the above named equivalent
amounts of any of the above named amines will result (in consequence of the joint
oxidation of these amines and of the acid sulphuretted compounds therein referred
to) in the production of a corresponding series of sulphuretted Indamines analogous,
in respect of both their composition and chemical properties, to the green Indamine
hereinbefore mentioned in the second example.
If now any
of the above said Indamines be further treated with a solution of
chloride of zinc at an elevated temperature, substantially in the manner herein-
before described in the first example, it will be transformed into a blue colouring
matter allied to methylene blue.
Of all these colouring matters allied to methylene blue, the blue colouring matter
resulting from the substitution of dimethylaniline by orthotoluidine in the first
example, as hereinbefore described, has hitherto yielded the best practical results.
In the above described process the chloride of zinc may be replaced by sulphate
of copper or other cupric salts, the action of which takes place at ordinary or gently
raised temperature. In this case on account of the oxidizing action of these salts
the above specified excess of oxidizing agent in the preparation of the sulphuretted
Indamines may be dispensed with. In practice however the employment of chloride
of zinc as hereinbefore described has been found to be preferable.
Having now particularly described and ascertained the nature of this said Invention
and in what manner the same is to be performed, I declare that what 1
claim is :-
:-
The process for the production of methylene blue and allied colouring matters,
which consists in acting first upon one molecule of paraamidodimethylaniline or. of
para-amidodiethylaniline or of para-amidomethylethylaniline with one molecule of
thiosulphuric acid (employed in the state of its sodium salt jointly with the requisite
amount of sulphate of alumina to produce thiosulphate of alumina or with a stronger
acid capable of liberating the thiosulphuric acid) and with as much bichromate of
potash (or other soluble chromate) as will perform the oxidizing action of about

page_text: one atom of oxygen, and then submitting the acid sulphuretted derivatives of -para-
amidodimethylaniline or of para-amidodiethylaniline, or of para-amido-methylethy-
laniline thus produced, to a joint oxidation with one molecule of either aniline,
orthotoluidine, dimethylaniline, methylethylaniline or diethylaniline, so as to produce
the corresponding sulphuretted Indamines, which are finally transformed into
methylene blue or allied colouring matters by the action of a solution of chloride
of zinc at about one hundred degrees Centigrade in the presence of an oxidising
agent (or by the action of cupric salts at a less elevated temperature) all substantially
in the manner hereinbefore described.