The Production and Manufacture of Azoxy and Azo Aldehydes, and of Colouring Matters therefrom.
Year: 1898

page_text: Date of Application, 19th Mar., 1898
Complete Snecificatton Left, 19th Dec., 1898 -Accepted, 11th Feb., 1899
PROVIDIONAL
The Production and Manufacture of Azoxy and Azo Aldehydes,
and of Colouring Matters therefrom.
.
We, ARTHUR GEORGE GREEN, F.I.C., F.C.S., of 13, King's Drive, Heaton Moor,
near Stockport, ANDRE RAOUL WAHL, of 331, Ashton New Road, Clayton, near
Manchester, and THE CLAYTON ANILINE COMPANY, LIMITED, Chemical Manufacturers,
of Clayton, near Manchester, do hereby declare the nature of our invention to be
as follows:-
Our invention relates to the preparation of azoxy and azo-aldehydes of the
benzene and stilbene series which having a sulphonic acid group (HSO,) in the
ortho position to each aldehyde group (CHO) form valuable intermediate
products for the preparation of fast green colouring-matters of the triphenyl-
methane series.
In the specification of Letters Patent 12922 granted to us and dated the 11th
June 1896 we have described a series of yellow orange colouring-matters obtained
by condensation of paranitrotoluene-sulphonic acid together with a dehydro-
thio-compound such as dehydrothiotoluidine sulphonic acid in the presence of
caustic alkalies.
It was subsequently found that when these products were submitted to
hydrolytic action, as for instance by heating them with dilute acids or by
treatment with nitrous acid, they were split up into the original dehydrothiotolui-
dine sulphonic acid (or its diazo derivative if nitrous acid was used) and new
colouring-matters, which though dyeing nearly the same shade as the original,
differed from them in solubility and other properties. It was found that these new
products possessed the characters of aromatic aldehydes and further investigation
showed that they were in fact mixtures of two series of aldehydes viz. :-
. Coloured azoxy or azo aldehydes of the stilbene series.
b. Colourless or slightly coloured azoxy or azo aldehydes of the benzene series.
The first series of aldehydes are strong cotton dyestuffs dyeing yellow to orange
shades and capable of being developed on the fibre with phenylhydrazine with the
production of dark orange to brick-red shades. Their phenylhydrazides formed in
substance dissolve in concentrated sulpuric acid with a red or violet colour.
The second series of aldehydes, which probably consist chiefly of the azoxybenz-
sulphonic acid
C,H, (CHO) (SO,H). N.. C,H, (CHO) (SO,H)
5 have no affinity for cotton, but are taken up by wool from an acid bath. The wool
is not coloured thereby but on subsequent treatment with an aqueous solution of
phenylhydrazine acquires a deep reddish brown colour. The phenylhydrazides
formed in substance are dark reddish-brown precipitates which dissolve in
concentrated sulphuric acid with a pure blue colour. The separation of the two

page_text: series of aldehydes is difficult but can be effected by fractional precipitation by salt
and by crystallization from dilute alcohol.
Subsequent investigation has shown that the same or a similar mixture of
aldehydes is obtained direct, without the intermediation of the dehydrothio
compound, by the action of very dilute caustic soda or other caustic alkali upon
paranitrotoluene sulphonic acid at as low a temperature as possible. It has
moreover been found that the same result can be effected still more advantageously
by long boiling of paranitrotoluenesulphonic acid with aqueous sodium carbonate
or potassium carbonate, and that the aldehyde formation even takes place to some
extent by heating the sodium salt of paranitro toluene sulphonic acid with water
alone under pressure at a temperature of about 140° to 160° Centigrade.
The formation of compounds containing the aldehyde group by alkaline
condensation of paranitrotoluenesulphonic acid is quite an unexpected and hitherto
unobserved reaction, the products of the transformation of paranitrotoluenesulphonic
acid under the influence of caustic alkalies having been always assumed to consist
of stilbene and dibenzyl derivatives alone.
In addition to the methods of preparation afforded by the above reactions, the
azoxy and azo-benzaldehyde sulphonic acids can also be obtained by the following
processes:
1. By oxidation in cold dilute aqueous solution by means of permanganates, of
certain colouring matters of the stilbene series known in commerce as curcumines S,
direct yellow, Mikado yellow, Mikado oranges and the like.
2. By alkaline reduction of the paranitrobenzaldehydeorthosulphonic acid formed
by oxidation of dinitrostilbene disulphonic acid in dilute solution as described in
the Berichte of the German Chemical Society Vol. 30 page 3097.
3. By alkaline oxidation of the paraamidobenzaldehydeorthosulphonic acid
obtained by reduction of the above paranitrobenzaldehydeorthosulphonic or by
another method.
4. By oxidation of diamidostilbenedisulphonic acid with permanganate in cold
dilute aqueous solution. In this reaction it is probable that paraamidobenzalde-
hydeorthosulphonic acid is formed as intermediate product according to the
equation:

page_text: phenylhydrazine required in the titration. The lead peroxide paste may be
replaced by other oxidising agents such as ferric chloride, potassium bichromate,
manganese dioxide and the like.
The following examples more fully illustrate the general method of carrying out
this invention but we do not confine ourselves to the precise details therein
contained as these admit of considerable variation.
EXAMPLE 1.
10 lbs. of the yellow colouring matter obtained by condensing paranitrotoluene
sulphonic acid with dehydrothiotoluidine sulphonic acid in the presence of dilute
caustic soda according to Example 1 in the Specification of the aforesaid Letters
To the solution cooled
Patent 12922 of 1896, are dissolved in 20 gallons of water.
to about 400 Centigrade 1 gallon of hydrochloric acid (33 %) is added and 1 gallon
of a solution of sodium nitrite (6.9% Na NO₂) is slowly run in. The thick reddish
brown precipitate becomes quite thin and changes to a light yellow precipitate of
diazodehydrothiotoluidine sulphonic acid After warming to 80° Centigrade the
latter is filtered off, the filtrate neutralised and the product salted out and dried.
By treatment with a 10 salt solution or with dilute alcohol the product can be
separated into a yellow aldehyde-colouring-matter and a colourless aldehyde having
the properties already described.
EXAMPLE 2.
70 lbs. of sodium paranitrotoluenesulphonate aro dissolved in 100 gallons of
water. 2 gallons of aqueous caustic soda (307 NaOH) are then added and the
mixture is heated at a temperature rising steadily during several days from 50° to
80° Centigrade. The mixture of coloured and colourless aldehydes can be salted
out and separated, or the solution can be titrated with phenylhydrazine and
employed directly for the preparation of green colouring-matters.
EXAMPLE 3.
100 lbs. of sodium paranitrotoluenesulphonate are dissolved in 50 gallons of water
with the addition of 10 lbs. of anhydrous sodium carbonate, and the solution is
boiled for 18 to 24 hours. The mixture slowly assumes a yellow colour but without
passing through the bluish-red characteristic of the first stage in the condensation
The progress of the
of paranitrotoluenesulphonic acid with caustic alkalies.
reaction is followed by taking samples at intervals and titrating with standard
phenylhydrazine solution. As soon as the maximum production of aldehyde is
reached the operation is stopped, as after passing this point the yield begins to
diminish again, probably through the formation of amido compounds by auto
reduction. This maximum is attained the more rapidly the greater the quantity of
sodium carbonate employed. The yellow liquid is neutralised with an acid and
poured into 300 gallons of 10 % salt solution. The aldehyde colouring matter
remains insoluble whilst the non-coloured aldehyde passes into solution and can be
salted out from the filtrate by further addition of salt. The former product is an
orange precipitate which dissolves in concentrated sulphuric acid with a reddish-
violet colour, dyes cotton orange-yellow and can be developed on the fibre with
phenylhydrazine. The latter product is a yellow powder which dissolves in
concentrated sulphuric acid with an orange colour, and does not dye cotton. Either
of the two products may be used for the preparation of green colouring-matters or
the mixture of the two may be employed directly without separation.

page_text: 28 lbs. of the mixed aldehydes obtained according to Example 1 are dissolved
together with 32 lbs. of sodium ethylbenzylanilinesulphonate in 25 gallons of water.
12 lbs. of concentrated sulphuric acid are added and the mixture is boiled for
10 or 15 hours. The product is diluted with 300 gallons of cold water and the
leuco compound is oxidised to the colouring-matter by the addition of 120 lbs.
of 10% lead peroxide paste and 12 lbs. of acetic acid. After decanting from the
lead sulphate the green solution is neutralised with ammonia, filtered and the
product salted out. It dyes wool green from an acid bath and is unaffected by
alkalies.
EXAMPLE 7.
35 lbs. of the non-coloured product of Example 3, équivalent to 6 lbs. of
phenylhydrazine, are dissolved in 50 gallons of water and boiled with 50 lbs. of
sodium-ethylbenzylaniline sulphonate (75 %) and 20 lbs. of concentrated sulphuric
acid for 12 or 14 hours. When the condensation is complete the leuco base is
salted out as a dark resinous mass which is dried. 50 lbs. of the latter are dissolved
in 500 gallons of water. 20 lbs. of concentrated sulphuric acid are added and the
mixture is oxidised by the addition of 70 lbs. of 24% lead peroxide paste. The
green solution is warmned, neutralised with ammonia, filtered from lead sulphate,
the filtrate concentrated and the colouring-inatter separated by addition of salt.
It forms a bronzy mass which dyes wool and silk from an acid bath a green fast to
alkalies.
EXAMPLE 8.
gallons of the solution of aldehydes obtained in Example 3 are diluted with
5 gallons of water and neutralised with dilute sulphuric acid. 10 lbs. of sodium
ethylbenzylaniline sulphonate (75%) and 4 lbs. of concentrated sulphuric acid are
added and the mixture is boiled for 12 hours. The leuco base is salted out and
dried. 10 lbs. of the latter are dissolved in 100 gallons of water, 5 lbs. of
concentrated sulphuric acid are added and the mixture is oxidised with the
theoretical quantity of lead peroxide. Like the product of the preceding example
it dyes a green fast to alkalies.
EXAMPLE 9.
10 gallons of a solution of azobenzaldehyde sulphonic acid, as obtained by
oxidation of Mikado orange 3RO in cold dilute aqueous solution with potassium
permanganate are titrated with phenylhydrazine and boiled with 2 molecular
proportions of ethylbenzylaniline sulphonic acid for each molecular equivalent of
phenylhydrazine. The lenco-baso obtained is salted out, re-dissolved in water,
acidified with sulphuric acid and oxidised with one molecular proportion of lead

page_text: peroxide to each molecular equivalent of phenylhydrazine. The filtrate from the
lead sulphate is salted out and the colouring matter separated and dried. It dyes
silk and wool a fast green.
Similar results are obtained if in place of the azobenzaldehyde sulphonic acid
there is employed the oxidation products of direct yellow curcumine S Mikado
golden yellow and the like, which are prepared by the action of potassium
permanganate on these colouring matters in cold dilute alkaline solution.
All the products dye silk and wool green to blue shades which are equally fast
against alkalies.
Dated this 19th day of March 1898.
The Production and Manufacture of Azoxy and Azo Aldehydes,
and of Colouring Matters therefrom.
We, ARTHUR GEORGE GREEN, F.I.C., F.C.S., of 13, King's Drive, Heaton Moor,
near Stockport, ANDRÉ RAOUL WAHL, of 331, Ashton New Road, Clayton, near
Manchester, and THE CLAYTON ANILINE COMPANY LIMITED, Chemical Manufacturers,
of Clayton, near Manchester, do hereby declare the nature of our
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
inven.
Our invention relates to the preparation of azoxy and azoaldehydes of the benzene
and stilbene series which having a sulphonic acid group (HSO,) in the ortho position
to each aldehyde group (CHO) form valuable intermediate products for the prepara-
tion of fast green colouring matters of the triphenylmethane series.
In the Specification of Letters Patent 12922 granted to us and dated the
11th June 1896 we have described a series of yellow orange colouring matters
obtained by condensation of paranitrotoluene-sulphonic acid together with a
dehydrothio compound such as dehydrothiotoluidine sulphonic acid in the presence
of caustic alkalies.
It was subsequently found that when these products were submitted to hydrolytic
action, as for instance by heating them with dilute acids or by treatment with
nitrous acid they were split up into the original dehydrothiotoluidine sulphonic
acid (or its diazo derivative if nitrous acid was used) and new colouring matters,
which though dyeing nearly the same shade as the original, differed from them
in solubility and other properties. It was found that these new products possessed
the characters of aromatic aldehydes and further investigation showed that they
were in fact mixtures of two series of aldehydes viz.:-
a. Coloured azoxy or azo aldehydes of the stilbene series.
b. Colourless or slightly coloured azoxy or azo-aldehydes of the benzene
series.
The first series of aldehydes are strong cotton dyestuffs dyeing yellow to orange
shades and capable of being developed on the fibre with phenylhydrazine with the
production of dark orange to brick red shades. Their phenylhydrazides formed
in substance dissolve in concentrated sulphuric acid with a red or violet
colour.

page_text: The second series of aldehydes, which probably consist chiefly of the azoxy
benzaldehyde sulphonic acid
U@Eg (CHU)(PU,H}+N,+CgHg (CHO) (BUgH),
have no affinity for cotton but are taken up by wool from an acid bath. The wool
is not coloured thereby but on subsequent treatment with an aqueous solution of
phenylhydrazine acquires a deep reddish brown colour. The phenylhydrazides
formed in substance are dark reddish brown precipitates which dissolve in
concentrated sulphuric acid with a pure blue colour. The separation of the two
series of aldehydes is difficult but can be effected by fractional precipitation by salt
and by crystallisation from dilute alcohol.
Subsequent investigation has shown that the same or a similar mixture of
aldehydes is obtained direct, without the intermediation of the dehydrothio
compound, by the action of very dilute caustic soda or other caustic alkali upon
paranitrotoluene sulphonic acid at as low a temperature as possible. It has more-
over been found that the same result can be effected still more advantageously by
long boiling of paranitrotoluene sulphonic acid with aqueous sodium carbonate or
potassium carbonate and that the aldehyde formation even takes place to some
extent by heating the sodium salt of paranitrotoluene-sulphonic acid with water
alone under pressure at a temperature of about 140° to 100° Centigrade.
The formation of compounds containing the aldehyde group by alkaline
condensation of paranitrotoluene-sulphonic acid is quite an unexpected and hitherto
unobserved reaction, the products of the transformation of paranitrotoluene sulphonic
acid under the influence of caustic alkalies having been always assumed to consist
of stilbene and dibenzyl derivatives alone.
In addition to the methods of preparation afforded by the above reactions the
azoxy- and azo-benzaldehyde sulphonic acids can also be obtained by the following
processes:
1. By oxidation of certain colouring matters of the stilbene series by means of
potassium permanganate in cold dilute aqueous solution as described in the
Specification of the application for Letters Patent No. 1431 of 1898.
2. By alkaline reduction of the paranitro benzaldehydeortho sulphonic acid
formed by oxidation of dinitrostilbene disulphonic acid in dilute solution as
described in the Berichte of the German Chemical Society Vol. 30 page 3097.
3. By alkaline oxidation of the paraamidobenzaldehydeortho sulphonic acid
obtained by reduction of the above paranitrobenzaldehyde-ortho-sulphonic or by
another method.
4. By oxidation of diamidostilbene disulphonic acid with permanganate in cold
dilute aqueous solution. In this reaction it is probable that paraamidobenzalde-
hydeortho sulphonic acid is formed as intermediate product according to the
equation
The above described azoxy or azo-aldehydes, by whichever method obtained,
are readily converted into fast green colouring matters of the triphenyl-methane 4
series by long boiling in slightly acid aqueous solution with secondary or tertiary
aromatic amines or their sulphonic acids the leuco compounds thus obtained being
subsequently oxidized in the usual manner. The mixture of coloured and colourless

page_text: aldehydes obtained by alkaline condensation of paranitrotoluenesulphonic acid can
be employed direct or the constituents can be separated in the above described
manner and separately condensed with amines. As however the shade and
properties of the products differ but slightly the employment of the mixture
without separation is to be preferred. Since the aldehydes by whichever method
obtained are of somewhat indeterminate composition we prefer in preparing the
green colouring matters therefrom to proceed in all cases in the following
manner.
The neutral solution of the aldehyde to which a little sodium acetate is added is
titrated with a standard solution of phenylhydrazine hydrochloride using a solution
of paranitrobenzaldehyde sulphonic acid as as an indicator. The condensation is then
made by employing two molecular proportions of the secondary or tertiary amine
to a quantity of the aldehyde solution which corresponds with one molecular
proportion of phenylhydrazine. When the condensation is complete the leuco-
compound is salted out, redissolved in water and oxidised with a quantity of lead
peroxide paste corresponding to one molecular proportion of P.BO₂ to each
molecular proportion of phenylhydrazine required in the titration. The lead
peroxide paste may be replaced by other oxidising agents such as ferric chloride,
potassium bichromate, manganese dioxide and the like.
The following examples more fully illustrate the general method of carrying out
this invention but we do not confine ourselves to the precise details therein
contained as these admit of considerable variation.
100 lbs. of sodium paranitrotoluene-sulphonate are dissolved in 50 gallon of
water with the addition of 10 lbs. of anhydrous sodium carbonate, and the solution
is boiled from 18 to 24 hours. The mixture slowly assumes a yellow colour but
without passing through the bluish red characteristic of the first stage in the
condensation of paranitrotoluene sulphonic acid with caustic alkalies. The progress
of the reaction is followed by taking samples at intervals and titrating with

page_text: standard phenylhydrazine solution. As soon as the maximum production of
aldehyde is reached the operation is stopped, as after passing this point the yield
begins to diminish again probably through the formation of amido compounds by
autoreduction. This maximum is attained the more rapidly the greater the quantity
of sodium carbonate employed. The yellow liquid is neutralised with an acid and
poured into 300 gallons of 10 % salt solution. The aldehyde colouring matter
remains insoluble whilst the non-coloured aldehyde passes into solution and can be
salted out from the filtrate by further addition of salt. The former product is an
orange precipitate which dissolves in concentrated sulphuric acid with a reddish
violet colour, dyes cotton orange-yellow and can be developed on the fibre with
phenyl-hydrazine. The latter product is a yellow powder which dissolves in
concentrated sulphuric acid with an orange colour, and does not dye cotton. Either
of the two products may be used for the preparation of green colouring matters or
the mixture of the two may be employed directly without separation.
6 lbs. of diamidostilbenedisulphonic acid are dissolved in 7 gallons of water with
the addition of sufficient sodium carbonate for neutralisation. The solution is cooled
to 0° Centigrade with ice and is oxidized by slowly running in whilst rapidly
agitating a cold solution of 6 lbs. of potassium permanganate in 15 gallons of water. 2
When the oxidation is complete the mixture is warmed, filtered from manganese
dioxide and the aldehyde salted out or its solution employed directly for
condensation.
28 lbs. of the mixed aldehydes obtained according to Example 1 are dissolved
together with 32 lbs. of sodium ethylbenzylaniline sulphonate in 25 gallons of
water. 12 lbs. of concentrated sulphuric acid are added and the mixture is boiled
for 10 or 15 hours. The product is diluted with 300 gallons of cold water and the
leuco compound is oxidised to the colouring-matter by addition of 120 lbs. of 10 %
lead peroxide paste and 12 lbs. of acetic acid. After decanting from the lead
sulphate the green solution is netralised with ammonia, filtered and the product
salted out. It dyes wool green from an acid bath and is unaffected by alkalies.
35 lbs. of the non-coloured product of Example 3 equivalent to 6 lbs. of phenyl-
hydrazine are dissolved in 50 gallons of water and boiled with 50 lbs. of sodium
ethylbenzylaniline sulphonate (75%) and 20 lbs. of concentrated sulphuric acid for
12 or 14 hours. When the condensation is complete the leuco base is salted out as
a dark resinous mass which is dried. 50 lbs. of the latter are dissolved in 500 gallons
20 lbs. of concentrated sulphuric acid are added and the mixture is
of water.

page_text: oxidised by the addition of 70 lbs. of 24 % lead peroxide paste. The green
solution is warmed, neutralised with ammonia, filtered from lead sulphate, the
filtrate concentrated and the colouring matter separated by addition of salt.
It forms a bronzy mass which dyes wool and silk from an acid bath a green
fast to alkalies.
10 gallons of a solution of azobenzaldehyde sulphonic acid, as obtained by
oxidation of Mikado orange 3 RO in cold dilute aqueous solution with potassuim
permanganate as described in the Specification of the application for Letters Patent
No. 1431 of 1898, are titrated with phenylhydrazine and boiled with 2 molecular
proportions of ethylbenzylaniline sulphonic acid for each molecular equivalent of
phenylhydrazine. The leuco base obtained is salted out, redissolved in water,
acidified with sulphuric acid and oxidised with one molecular proportion of lead
peroxide to each molecular equivalent of phenylhydrazine. The filtrate from the
lead sulphate is salted out and the colouring matter separated and dried. It dyes
silk and wool a fast green.
Similar results are obtained if in place of the azobenzaldehydesulphonic acid
there is employed the oxidation products of direct yellow, curcumine S, Mikado
golden yellow and the like, which are prepared by the action of potassium
permanganate on these colouring matters in cold dilute alkaline solution as described
in the Specification of the application for Letters Patent No. 1431 of 1898. All the
products dye silk and wool green to blue shades, which are equally fast against
alkalies.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The herein before described processes for the production and manufacture of
azoxy and azo aldehydes of the benzene and stilbene series or of mixtures
thereof.
(a) By hydrolysis of the colouring-matters prepared under Letters Patent
12922 of 1896.
(b) By heating paranitrotoluenesulphonic acid with solutions of alkaline
carbonates or with very dilute caustic alkalies.
2. The manufacture and production of azoxy- and azo-benzaldehyde sulphonic
acids.
(a) By oxidation of diamidostilbenedisulphonic acid with potassium perman-
ganate in the cold.
(b) By alkaline reduction of paranitrobenzaldehyde-ortho-sulphonic acid.
3. The manufacture and production of green colouring-matters, fast to alkali,
from the azoxy and azo aldehydes obtained according to the preceding claims,
or in accordance with the Specification of the application for Letters Patent
No. 1431 of 1898 by oxidation of colouring-matters of the stilbene-series; by

page_text: condensing the same with secondary, or tertiary, aromatic amines, or sulphonic
acids thereof, and oxidation of the leuco compounds thus obtained.
4. As new articles of manufacture the colouring-matters and their intermediate
compounds, such as are obtained according to the processes claimed in either of the
preceding claiming clauses.
1
1000
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.