IMPROVEMENTS IN THE PRODUCTION OF COLOURING MATTERS FROM PARA-NITROBENZALDEHYDE, OR FROM ITS DERIVATIVES AND AROMATIC BASES
Year: 1881

page_text: LETTERS PATENT to Joseph Anthony Dixon, of No. 175, West George Street,
Glasgow, in the County of Lanark, North Britain, Solicitor, for an Invention
of "IMPROVEMENTS IN THE PRODUCTION OF COLOURING MATTERS FROM
PARA-NITROBENZALDEHYDE, OR FROM ITS DERIVATIVES AND AROMATIC
BASES." A communication from abroad by Doctor Otto Fischer, Privat
Docent, in the University of Munich, in the Kingdom of Bavaria.
PROVISIONAL SPECIFICATION left by the said Joseph Anthony Dixon at
the Office of the Commissioners of Patents on the 19th March 1881.
JOSEPH ANTHONY DIXON, of 175, West George Street, Glasgow, in the County
of Lanark, North Britain, Solicitor. "IMPROVEMENTS IN THE PRODUCTION OF
COLOURING MATTERS FROM PARA-NITROBENZALDEHYDE OR FROM ITS DERIVATIVES
AND AROMATIC BASES." [A communication from abroad by Doctor Otto Fischer,
Privat Docent, in the University of Munich, in the Kingdom of Bavaria.]
In the years A.D. 1878 and 1879 Doctor Otto Fischer, from whom I have
received the communication of this Invention, discovered a method for the
preparation of amido derivatives of triphenylmethan by the action of benzaldehyde
on aromatic amido bases in presence of dehydrating agents.
These amido derivatives of triphenylmethan, known to chemists under the name
of louco-bases, give by oxidation colouring matters, which according to our present
knowledge are closely related to rosaniline and its derivatives.
One of these colouring matters is already being prepared on a commercial scale,
and is being sold under the names of bitter-almond-oil-green, Victoria green, and
malachite green.
This green is obtained by oxidizing the tetramethyldiamidotriphenylmethan
discovered by the said Otto Fischer, and which is formed from benzaldehyde and
dimethylaniline in presence of dehydrating agents according to the formula,-
CH, COH + 20,HN (CH) 2 = H₂O + C₂H₂CH [C. H.N (CH₂)2]2.
[Price 4d.]

page_text: The nature and object of the present Invention consists in producing colouring
matters from those derivatives of triphenylmethan that are formed by the action
of paranitrobenzaldehyde or its derivatives on aromatic bases in presence of
dehydrating agents.
I explain or illustrate the production of these colouring matters by the following
examples:-
-
First. Paranitrobenzaldehyde heated with dimethylaniline in presence of
dehydrating agents produces paranitrotetramethyldiamidotriphenylmethan, which
treated with oxidizing agents produces paranitro-bitter-almond-oil-green.
Second. Dimethylpararosaniline can be produced by condensing the paranitro-
benzaldehyde with toluidine (in the form of one of its salts), reducing the thus
obtained paranitrodiamidodimethyltriphenylmethan and oxidizing this leuco base
by means well known to chemists. To convert the paranitrodiamidodimethyl-
triphenylmethan into dimethylpararosaniline in one operation I heat at a
temperature of 160° to 180° Celsius (320°-366° Fahrenheit) the nitro-leucobase
with chlorure or protochloride of irọn (Fe Cl) or with other metallic salts having
similar effect.
Third. The same leucobases that are obtained by reducing the condensation-
product of paranitrobenzaldehyde, and aromatic bases can also be produced direct
by allowing the paraamidobenzaldehyde obtained by the reduction of paranitro-
benzaldehyde to react on aromatic bases in presence of dehydrating agents.
Methylpararosaniline can accordingly be obtained from paranitrobenzaldehyde
by the two following processes:-
A. I heat on an oil bath a mixture of aniline and toluidine (in the form of one
of their salts) with paranitrobenzaldehyde, while adding chloride of zinc or some
other similar dehydrating agent until the reaction is completed; the paranitro-
diamidomethyltriphenylmethan thus obtained is reduced by means of tin and
muriatic acid, or by means of any other usual reducing agent and converted into
methylparaleucaniline and then oxidized.
B. By reducing the paranitrobenzaldehyde I first obtain paraamidobenzalde-
hyde; I heat on an oil bath the paraamidobenzaldehyde (in form of one of its
salts) with a mixture of an aniline salt and toluidine salt in presence of
dehydrating agents. From the reaction-product I separate in manner well known
to chemists the methylparaleucaniline so formed, and I convert it by oxidation
into methylpararosaniline.
Fourth. The leuco bases mentioned under heads first and second can by treatment
with sulphuric acid be converted into sulphoacids, and these by oxidation may be
converted into colouring matters soluble in water.
The colouring matters mentioned under, heads first and second can also be
sulphonated.
Fifth. The leuco bases produced according to the first and second heads can be
first methylized, ethylized, phenylized, or benzylized, and by subsequent oxidation
can be converted into colouring matters.
The same colouring matters are also obtained by methylizing, ethylizing,
phenylizing, or benzylizing the colouring matters produced according to examples
first and second.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Joseph, Anthony Dixon in the Great Seal Patent Office on the
10th September 1881.
JOSEPH ANTHONY DIXON, of 175, West George Street, Glasgow, in the County
of Lanark, North Britain, Solicitor. "IMPROVEMENTS IN THE PRODUCTION OF
COLOURING MATTERS FROM PARA-NITRO-BENZALDEHYDE OR FROM ITS DERIVATIVES
AND AROMATIC BASES." A communication from abroad by Doctor Otto Fischer,
Privat Docent, in the University of Munich, in the Kingdom of Bavaria.
In the years A.D. 1878 and 1879 Doctor Otto Fischer, from whom I have
received the communication of this Invention, discovered a method for the
preparation of amido derivatives of triphenylmethan by the action of bonzaldhyde
on aromatic amido bases in presence of dehydrating agents.
These amido derivatives of triphenylmethan, known to chemists under the name
of leuco-bases, give by oxidation colouring matters which according to our present
knowledge are closely related to rosaniline and its derivatives.
One of these colouring matters is already being prepared on a commercial scale,
and is being sold under the names of bitteralmondoil-green, Victoria green, and
malachite green.
This green is obtained by oxidizing the tetramethyldiamidotriphenylmethan
discovered by the said Otto Fischer, and which is formed from benzaldehyde and
dimethylaniline in presence of dehydrating agents according to the formula,-
CH, COH + 2 C, H, N(CH₂) 2 = H₂O + C H¸ CH [C¸ H N (CH) 2] 2.
The nature and object of the present Invention consist in producing colouring
matters from those derivatives of triphenylmethan that are formed by the action of
para-nitro-benzaldehyde (or certain of its derivatives hereinafter mentioned) on the
aromatic bases herinafter mentioned in presence of dehydrating agents. By the
derivatives of para-nitro-benzaldehyde bere and elsewhere throughout this Specifi-
cation I mean particularly the substitution derivatives in which one or more of the
hydrogen atoms of its benzolic nucleus is or are replaced by bromine, chlorine, or
iodine, or sulpho, or nitro group or groups.
I explain or illustrate the nature and mode of producing these colouring matters
by the following examples :-
First. Colouring matters produced by the oxidation of the compounds or derivatives
of triphenylmethan which contain a para-nitro group.
I take as an example of these colouring matters the following:-Para-nitro-
benzaldehyde (or one of its derivatives above described) digested for a considerable
period at about 120° centigrade with dimethylaniline in presence of dehydrating
agents, produces by condensation of the para-nitro-benzaldehyde with the
dimethylanilin accompanied by separaration of the elements of water, the leuco-
base paranitrotetramethyldiamidotriphenylmethan (or the substituted leuco-base
corresponding to the substituted derivative used), which condensation product or
leuco-base when treated with oxidizing agents produces the colouring matter
which I call para-nitro-bitter-almond-oil green (or a substituted colouring matter
corresponding thereto).
"
In like manner para-nitro-benzaldehyde or any of its said derivatives forms para-
nitro condensation products (which are leuco-bases analogous to the said para-nitro-
tetra-methyl-diamido-triphenylmethan) when the said para-nitro-benzaldehyde or
any of its said derivatives is beated in presence of dehydrating agents along with
any of the following aromatic bases, viz. :--
(a). With anilin (preferably, as will be obvious to a chemist, in the form of any
suitable salt thereof, as the hydrochlorate).

page_text: (b). With any of the derivatives which originate from anilin through substitution
of one or both of the hydrogen atoms of the amido group by methyl, ethyl, phenyl,
benzyl, or other like radicle or radicles of the fatty or aromatic series (preferably
in the form of a salt like the hydrochlorate).
(c). With the substitution products of anilin in which one or more hydrogen
atoms of the benzol nucleus (with the exception of that bydrogen atom which
occupies the para position relatively to the amido group) is or are replaced by
methyl, ethyl, benzyl, phenyl, or other like alcohol radicle of the fatty or aromatic
series, hydroxyl, methoxyl, ethoxyl, or the nitro amido or sulpho group (such
substitution products being of course preferably used in the form of a salt when
they are capable of forming salts), and the leuco-bases so obtained on being treated
with oxidizing agents yield para nitro colouring matters analogous to para-nitro-
'bitter-almond-oil green.
I desire to explain that the para-nitro condensation product derived in manner
above explained from para-nitro-benzaldehyde and anilin, and which may be
designated. para-nitro-diamido-triphenylmethan has been already described by
the said Doctor Otto Fischer and Philip Greiff in the Berichte der Deutschen
Chemischen Gesellschaft (Jahr. xiii., heft 6), together with a leuco-base derived
therefrom by reduction with zinc dust and acetic acid which appears to be identical
with para leucanilin, as also the production of fuchsin or para-rosanilin by
oxidizing the said reduction product with bichloride of mercury or heating with
hydrochloric acid, and accordingly I do not claim the said para-nitro-diamido-
triphenylmethan, nor the said leuco-base apparently identical with para leucanilin,
nor the production of fuchsin therefrom by oxidation, but the said paper does not
contain any statement of the production of colouring matter analogous to para-
nitro-bitter-almond-oil green by oxidizing, the said para-nitro-diamido-triphenyl-
methan, and I therefore claim as new the production of the said colouring matter
by oxidizing para-nitro-diamido-triphenylmethan; and I also claim as new the
production (as a step towards the production of the colouring matters after-
mentioned) of the leuco-bases analogous to the said para-nitro-diamido-triphenyl-
methan by condensing para-nitro-benzaldehyde and any of the bodies herein before
specified under the paragraphs headed (b) and (c), as well as the production by
oxidizing the leuco-bases last above mentioned of colouring matters analogous to
para-nitro-bitter-almond-oil green.
Second. Colouring matters produced by reducing the para nitro group in the
above mentioned compounds or derivatives of triphenylmethan which contain
that group, and then oxidizing the leuco-bases resulting from such reduction.
As an example of these colouring matters I take the following case :—
Dimethylpararosaniline is produced by condensing the para-nitro-benzaldehyde
with toluidine (preferably in the form of one of its salts, such as the hydrochlorate),
.e., by heating it with toluidine in presence of dehydrating agents and then
reducing, by means well known to chemists, the thus obtained para-nitro-diamido-
dimethyl-triphenylmethan to the corresponding para-amido, compound or leuco-
base, and oxidizing the said leuco-base resulting from the reduction by means also
well known to chemists. The aforesaid substituted derivatives of para-nitro-
benzaldehyde will yield with toluidine like-substituted dimethyl-para-rosaniline
compounds.
To convert the para-nitro-diamido-dimethyl-triphenylmethan into dimethyl-para-
rosaniline in one operation I heat at a temperature of 160° to 180° Celcius (320° to
360° Fahrenheit) the nitro-leuco-base with protochloride of iron (Fe C₁₂) or with.
other metallic salts having similar effect.
Colouring matters analogous to the dimethyl-para-rosanilin so obtained may be
obtained by oxidizing in a similar way the leuco-bases produced by reducing the
para-nitro group of those para-nitro-leuco-bases (bodies analogous to the said para-
nitro-diamido-dimethyl-triphenylmethan) which are to be got by condensing in
manner above described or exemplified para-nitro-benzaldehyde (or its substituted

page_text: derivatives as aforesaid) with (in place of toluidine) any of the other aromatic
bases.specified under the paragraphs headed (a), (b), and (c) hereinbefore written.
Or the said para-nitro-leuco-bases may by reduction and oxidation effected in
manner before mentioned in one operation be converted into the same colouring
matters. As already mentioned, the said Otto Fischer and Philip Greiff have
already published the process of producing fuchsin or para rosaniline by oxidizing
the para-amido-leuco-base obtained by reducing the para-nitro group of the.
condensation product of para-nitro-benzaldehyde and anilin, and I accordingly do
not claim the production in that way of fuchsin or para-rosanilin, nor the production
of the said para-amido-leuco-base obtained by the said reduction, but I claim the
production in manner mentioned of the other colouring matters analogous to para-
rosanilin by reducing the para-nitro-leuco-bases or condensation products got by
condensing para-nitro-benzaldehyde or its substituted derivatives, and the aromatic
bases mentioned under said paragraphs (a), (b), and (c), other than anilin and
oxidizing the leuco-bases so obtained, and I also claim the production of said other
colouring matters by the simultaneous reduction and oxidation of the said para-
nitro-leuco-bases, and also (as a step towards the production of said colouring
matters) I claim the production of the said para-amido-leuco-bases themselves
(other than that obtained from anilin) by reduction of the corresponding para-
nitro bases above mentioned.
Third. Colouring matters produced by first reducing para-nitro-benzaldehyde and
then condensing the reduction product with aromatic bases and oxidizing the
condensation-products so obtained.
The same leuco-bases that are obtained by reducing the condensation-product of
para-nitro-benzaldehyde (or a derivative thereof) and aromatic bases as berein-
before described under head second, can also be produced directly by an alternative
process, viz.,. by allowing the para-amido-henzaldehyde (or substituted para-amido
body corresponding to the derivative used) obtained by the reduction of para-nitro-
benzaldehyde (or derivative thereof) to react on the aromatic bases hereinbefore
specified under said paragraphs headed (a), (b), and (e), in presence of dehydrating
agents, and these leuco-bases on being oxidized as before described give the same
colouring matters which are obtained as the ultimate products of the process
herein before described under heading second.
Methylpararosaniline, for example, can be obtained from para-nitro-benzaldehyde
by either of the two following processes :-
First Process (which is the process described under heading second, herein before
written). I heat on an oil bath a mixture of aniline and toluidine (in the form of
one of their salts) with para-nitro-benzaldehyde, while adding chloride of zinc or
soine other similar dehydrating agent until the reaction is completed; the para-nitro-
diamido-methyl-triphenyl-methan thus obtained is reduced by means of tin and
muriatic acid or by means of any other usual reducing agent and converted into
methyl-para-leuco-aniline which is then oxidized into methyl-para-rosaniline, or
Second Process. By reducing the para-nitro-benzaldehyde I first obtain para-
amido-benzaldehyde; I heat on an oil bath the para-amido-benzaldehyde (in form
of one of its salts) with a mixture of an aniline salt and toluidine salt in presence
of dehydrating agents. From the reaction product I separate in manner well
known to chemists the methyl-para-leuk-aniline so formed, and I convert it by
oxidation into methyl-para-rosaniline.
I wish to explain with regard to the process described under this heading of
preparing the said leuco-bases and colouring matters by acting with the para-
amido-benzaldehyde or its said derivatives on the said aromatic bases, and of
preparing colouring matters by oxidation of the leuco-bases so obtained, `that I
claim this process as applied to the production (as a step towards para rosanilin)
of the leuco-base so obtained from para-amido-benzaldehyde or its derivatives and
anilin, and to the production of para rosanilin by oxidation of that leuco-base, and
do not restrict my claim in regard to the application of this process to the production

page_text: benzaldehyde or its derivatives and the said aromatic bases other than anilin.
Fourth. Colouring matters produced by methylizing and otherwise alkylizing the
leuco-bases and then oxidizing the alkylized product, or by alkylizing the
colouring matters produced by first oxidizing the leuco-bases.
The leuco-bases herein before mentioned (whether, para-nitro or para-amido
leuco-bases) may be first methylized, ethylized, phenylized, or benzylized (in manner
well known to chemists), and then by subsequent oxidation converted into colouring
matters. Or the same or similar colouring matters may also be obtained by
methylizing, ethylizing, phenylizing, or benzylizing the colouring matters produced
by first oxidizing the said leuco-bases (whether para-nitro or para-amido bases), or
by the simultaneous reduction and oxidation, in manner hereinbefore described, of
the para-nitro-leuco-bases hereinbefore mentioned. The alkylizing of the said
leuco-bases and colouring matters may be effected whether a sulpho group or
groups has or have previously been introduced into the said leuco-bases, or colouring
matters or not.
Fifth. Colouring matters produced by sulphonating the said leuco-bases and then
oxidizing the resulting sulpho acids, or by sulphonating the colouring matters
that are produced by oxidizing the said leuco-bases.
The leuco-bases bereinbefore mentioned, whether para-nitro-leuco-bases or para-
amido-leuco-bases, can by treatment with sulphuric acid be converted (by the now
well understood process for preparing organic sulpho acids) into sulpho acids,
and these by oxidation may be converted into colouring matters soluble in
water.
The colouring matters obtained by oxidation of the said leuco-bases (whether
para-nitro or para-amido bases) can also be sulphonated in order to obtain colouring
matters more readily soluble in water. The sulphonization of the said leuco-bases
and of the said colouring matters is not practically affected by the said leuco-bases
or colouring matters having been previously alkylized, and can be effected whether
they have been previously alkylized in manuer hereinbefore described or not.
It is the leuco-base or oxidized leuco-base which the sulphuric acid attacks
and modifies, and not the alkyl radicle which may have also been coupled
with it.
I am acquainted with the Specification No. 3731, A.D. 1877, of Dr. Heinrich
Caro's Invention for converting the basic colouring matters of "the rosaniline
group" therein described and defined into sulpho acids, and I do not claim the
sulphonating of the fuchsin or para-rosaniline colouring matter obtained as herein-
before described by oxidation of the reduced condensation product of para-nitro-
benzaldehyde and anilin, nor of the other colouring matters analogous thereto
hereinbefore described, in so far as the sulphonating of said colouring matters may
· be included in the said Specification.
Having now particularly ascertained and described the nature of the said
Invention, and the manner of performing the same, I desire to state that subject to
the disclaiming clauses hereinbefore contained with regard to particular bodies or
products hereinbefore specially excepted from my claims, I claim as novel and as
covered by the said hereinbefore in part recited Letters Patent,—
First. The product of para-nitro colouring matters by oxidizing in manner
hereinbefore described the para-nitro condensation products of leuco-bases obtained
in manner hereinbefore described by heating para-nitro-benzaldehyde or any of its
said derivatives along with any of the aromatic bases specified in the paragraphs
headed (a) (b) and (c) hereinbefore contained in presence of dehydrating agents.
Second. The production, as a step towards the production of the said para-nitro
colouring matters of the said para-nitro condensation products or leuco-bases by
heating para-nitro-benzaldehyde or any of its said derivatives with any of the said

page_text: aromatic bases in presence of dehydrating agents, all in manner hereinbefore
described.
Third. The production of colouring matters (1) by first reducing the para-nitro
condensation products obtained by heating in presence of dehydrating agents para-
nitro-benzaldehyde or any of its said derivatives with any of the said aromatic
bases, and then oxidizing the leuco-bases obtained by such reduction; or (2) by
first reducing the para-nitro benzaldehyde or its derivative to the corresponding
para-amido body, then heating the para-amido body with any of the said aromatic
bases in presence of dehydrating agents, so as to obtain a para-amido condensation
product or leuco-base, and finally oxidizing the condensation product or leuco-base
so obtained; or (3) by reducing and oxidizing the said para-nitro condensation
products in one operation by heating the same with protochloride of iron or other
metallic salts having a similar effect, all in manner hereinbefore described.
Fourth. The production, as steps towards the production of the colouring matters
referred to in the immediately preceding claim, of the said para-nitro condensation
products and of the leuco-bases obtained by reduction thereof, or by condensing
para-amido-benzaldehyde or its derivatives along with the said aromatic bases, all
in manner hereinbefore described.
Fifth. The production of colouring matters (1) by methylizing, ethylizing,
phenylizing, or benzylizing the leuco bases referred to in the preceding claims
whether previously sulphonated or not, and then oxidizing the products so
obtained; or (2) by first forming the colouring matters which result from oxidation
of the said leuco-bases (whether para-nitro or para-amido) or from the simultaneous
reduction and oxidation of the para-nitro bases, and then whether the said colouring
matters have been previously sulphonated or not, methylizing, ethylizing, phenylizing,
or benzylizing the colouring matters so obtained.
Sixth. The preparation of colouring matters (1) by sulphonating the said leuco-
bases whether previously alkylized or not, and then oxidizing the sulphonated
product; or (2) by sulphonating the colouring matters obtained by oxidation of the
said leuco-bases whether previously alkylized or not.
In witness whereof, I, the said Joseph Anthony Dixon, have hereunto set my
hand and seal, this Sixth day of September, in the year of our Lord One
thousand eight hundred and eighty one.
JOSEPH ANTHONY DIXON. (L.B.)