Manufacture of Dyestuffs of the Series known as "Patent Blue."
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Manufacture of Dyestuffs of the Series known as "Patent Blue."
I, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the County
of London, Chartered Patent Agent, do hereby declare the nature of this invention
(which has been communicated to me from abroad by The Farbwerke vormals Meister
Lucius and Brining, of Hoechst a/Maine in the German Empire, Chemical
Manufacturers) to be as follows:-
Amongst the dyestuffs of the triphenylmethane series those of the "patent blue"
group are particularly remarkable for their fastness and property of dyeing evenly.
The properties of these bodies depend upon the "ortho" position of a sulpho group
relatively to the methane carbon atom and the following reactions are highly
characteristic for all these sulpho acids:-
1.) If the weak mineral acid solution of the leuco-compound be boiled with ferric
chloride, a blue-green solution is formed, which on being saturated with ammonia
produces an intensely blue filtrate.
2.) All "patent-blue" dyestuffs on boiling their aqueous solution with soda-lye
split off alkylamine and form violet to yellow-red solutions of phenoldyestuffs.
The dyestuffs hitherto known of the "patent-blue" group belong mostly to the
diamidotriphenylmethane series. My correspondents have discovered very valuable
dyestuffs of the "patent-blue" group which are derivatives of triamidodiphenyl-o-
tolylmethane:
and triamidotri-o-tolylmethane.
These dyestuffs may be obtained in various ways:-
1.) By sulphonating the alkylated derivatives of triamidodiphenyl-o-tolylmethane,
or triamidotri-o-tolylmethane, and by oxidation of the leucosulphonic acids thus
obtained, or by first oxidising and subsequently sulphonating the leucobases, i.e. by
sulphonation of the corresponding dyestuffs.
2.) By condensation of alkylated diamidobenzhydrol (diamidotolylhydrol) with the
sulphonic acids of alkyl-o-tolylamines and by oxidation of the leucosulphonic acids
thus obtained.

page_text: I. MANUFACTURE OF LEUCO-COMPOUNDS OF THE "PATENT-BLUE" SERIES FROM
ALKYLATED TRIAMIDODIPHENYLO-TOLYLMETHANES.
The leucobases here referred to are obtained according to the Specification to the
German Letters Patent No. 27032 of October 23rd 1883. As an example there is
here chosen the leucobase from monobenzyl-o-toluidine and tetramethyldiamido- 5
benzhydrolie.
My correspondents have found that by condensation of monobenzyl-o-toluidine with
tetramethyldiamidobenzhydrol two isomeric hases are found, both of which produce
violet basic dyestuffs on being oxidised, but which behave quite differently on being
sulphonated. The one base (called "a") only produces a violet acid-dyestuff or its
lencosulphonic acids respectively, whilst the other base (called "B"), when treated
with weak sulphonating agents (such as sulphuric acid mnonohydrate) produces a
monosulphonic acid, the leucosulphonic acid of a violet dyestuff, and when more
energetically sulphonated a disulphonic acid which proves to be the leuco-compound
of a blue dyestuff of the "patent-blue" series. By an appropriate choice of the
condensation agent it is possible to obtain either base "a" or base "B" in predominating
quantity. If tetramethyldiamidobenzhydrol be condensed with monobenzyl-o-
foluidine in hydrochloric acid solution, base "a" is mostly formed; in sulphuric acid
solution base "B" is formed, and in this case up to 90% of the theoretical quantity
of base "B" may be obtained.
Both leucobases are easily separated; from the mineral acid solution base "a" is
precipitated as a resinous hydrochloride by adding a solution of common salt, whilst
base "B" remains dissolved and is precipitated by alkali from the filtrate as a
crystalline sediment.
40 kil. of this leucobase "B" are dissolved in 200 kil of fuming sulphuric acid of
20% SO, and this solution is heated for 4 to 5 hours up to 60 to 70° C., until the
intensity of the ferric chloride reaction (see above) no longer increases. The product
of the reaction is poured into water and transformed in the usual way into the calcium
or sodium salt.
Instead of monobenzyltetramethyltriamido-o-tolyldiphenylmethane the following,
for instance, may be employed in quite a similar manner :-

page_text: II. MANUFACTURE OF LEUCO-COMPOUNDS OF THE "PATENT-BLUE" SERIES BY
CONDENSATION OF ALKYLATED BENZHYDROLS WITH SULPHONIC ACIDS OF
ALKYL DERIVATIVES OF O-TOLUIDINE.
The alkylated o-toluidines are easily transformed into sulphonic acids. Monomethyl
and monoethyl-o-toluidine produce with fuming sulphuric acid monosulphonic acids
which crystallise well and are soluble in water with difficulty; monobenzyl-o-
toluidine forms a monosulphonic acid, if the solution of the base in monohydrate be
mixed with fuming sulphuric acid, and a disulphonic acid, if the base be dissolved in
oleum containing 20% SO. It is very remarkable, that in the monosulphonic acid
of benzyl-o-toluidine the sulpho group enters in the tolylradical and not the
benzylradicalland that in the disulphonic acid the second sulphoxyl group enters the
benzyl group.
As example for this method is taken the condensation of tetramethyldiamido-
benzhydroli with monobenzyl-o-toluidine disulphonic acid:
27 kil. of tetramethyldiamidobenzhydrol are dissolved in 35 kil. of hydrochloric
acid of 31% HCl. and 130 litres of water; to this solution are added 40 kil: of
calcium salt of monobenzyl-o-toluidinedisulphonic acid dissolved in 500 litres of
water. This solution is heated on the waterbath for 10 to 12 hours, until
disappearance of the hydrol, i.e. until a sample is completely dissolved by ammonia.
The solution is mixed with soda until a weak alkaline reaction takes place, then
filtered off from the separated carbonate of calciam, salted out from the filtrate of the
leucosalt and finally dried.
Instead of tetramethyldiamidobenzhydrol; my correspondents have employed with
the same effect, for instance:
totooth aldiamidobanzhudrol
35
dimethyldiamidodi-o-tolymyaror
and instead of
monobenzyl-o-toluidine disulphonic acid
monobenzyl-o-toluidine monosulphonic acid
monomethyl-o-
monoethyl-o-
"
The monosulphonic acids resulting from this method are easily further sulphonated
10 and the dyestuffs treated in this manner are of greater value, as is shown by the
following example:-

page_text: sulphonic acid and tetramethyldiamidobenzhydrol, which crystallizes in beautiful
silvery lamine, are dissolved in 200 kil. of fuming sulphuric acid of 20% SO₁: At
the ordinary temperature a disulphonic acid is formed. The product. of the reaction
is transformed into the calcium salt in the usual way.
III. METHOD FOR THE OXIDATION OF THE LEUCOSULPHONIC ACIDS.
As example is chosen the oxidation of the leucosalt from monobenzyl-o-toluidine-
disulphonic acid and tetramethyldiamidobenzhydrol.
10 kil. of this leucosalt are dissolved in 300 litres of water, the solution heated
to 60-70° C., thoroughly stirred up with the calculated quantities of acetic acid and
peroxyde of lead and then '6 kil. of Glauber's salt are added in order to precipitate
the lead. The intensely blue coloured solution is filtered off from the sulphate of
lend and the dyestuff is precipitated with common salt or the solution is evaporated
to crystallisation.
The dyestuff is characterised by its great power of crystallisation, forming copper-
coloured crystals, easily soluble in water with a blue colour. The aqueous solution is
dichroïtic; it has a blue red colour in direct light and a blue green one is reflected
light. Ammonia and soda do not change the colour of the solution; boiling with
soda-lye turns it violet. The dyestuff dyes wool and silk blue in an acid bath. The
tints are very even and fast to soap, water, air and light.
All leucosalts as described above are oxidised in a similar manner. The various
dyestuffs hardly differ in their properties. Generally speaking the monosulphonic
acids draw much less regularly in an acid bath than the disulphonic acids and it is
characteristic for the dyestuffs, that the monosulphonic acids also draw on wool and
fanned cotton in a neutral bath.
lustead of first sulphonating and then oxidising the leucobases, as is described in
Paragraph I, the dyestuffs corresponding to these leucobases may also be sulphonated
into patent-blue" dyestuffs, for instance:-
10 kil. of monobenzyltetramethyltriamidodiphenyl-o-tolylcarbinol are dissolved
in 50 kil. of fuming sulphuric acid of 20% SO, and this solution is gently heated
until a sample boiled with soda-lye exhibits the characteristic reaction of the bodies
of the "patent-blue series." The transformation of the product of the reaction into
dyestuff is carried out in the usual manner.
Dated this 24th day of December 1896.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Manufacture of Dyestuffs of the Series known as "Patent Blue."
I, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention (which has been communicated to ine from abroad by The Farbwerke
vormals Meister Lucius and Brüning, of Hoechst a/Maine in the German Empire,
Chemical Manufacturers) and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
Amongst the dyestuffs of the triphenylmethane series those of the "patent blue"
group are particularly remarkable for their fastness and property of dyeing evenly.
The properties of these bodies depend upon the "ortho" position of a sulpho group
relatively to the methane carbon atom, and the following reactions are highly
characteristic for all these sulpho acids -
1.) If the weak mineral acid solution of the leuco-compound be boiled with ferric

page_text: chloride: a blue-green solution is formed which on being saturated with aminonia
produces an intensely, blue, filtrate...
2.) All patent blue" dyestuffs, on boiling their aqueous solution with caustic
soda-lye, split off alkylamine: and form violet to yellow-red solutions; of
phenoldystuffs.
The dyestuffs hitherto known of the "patent blue" group belong mostly to, the
diamidotriphenylmethane series. My correspondents have discovered very valuable.'
dyestuffs of the "patent blue" group which are derivatives of triamidodiphenyl-o-.
tolylmethane:
"
produces an intensely blue,filtrate..
2.) All patent blue" dyestuffs, on boiling their aqueous solution with caustic
soda-lye, split off alkylamine: and form violet to yellow-red solutions; of
phenoldystuffs.
The dyestuffs hitherto known of the "patent blue" group belong mostly to, the
diamidotriphenylmethane series. My correspondents have discovered very valuable.'.
dyestuffs of the "patent blue" group which are derivatives of triamidodiphenyl-o-.
tolylmethane:
-
CHẠNH
CH – CH,NH,
-
NH₂
CH,
These dyestuffs may he obtained by condensation of alkylated diamidobenzhydrosl
with the sulphonic acids of mono-alkylated o-toluidine (mono-methyl-mono-ethyl-o-
toluidine-monosulphonic acid, mono-benzyl-o-toluidine-mono- and disulphonic acids)
and by oxidation of the leucosulphonie acids thus obtained.
It is to be observed, that on sulphonating the benzyl-o-toluidine the sulphonic
group enters first into the tolyl residue and not the benzyl residue. The mono-
sulplionic acid of monobenzyl-o-toluidine is produced if the solution of the base in
monohydrated sulphuric acid be mixed with fuming sulphuric acid; the disulphonic
acid is produced if the base be dissolved in fumning sulphuric acid. The condensation
of alkylated diamidobenzhydrols with monoalkyl-o-toluidine sulphonic acids is
illustrated by the following example:-
27:0 Kil. of tetramethyldiamidobenzhydrol are dissolved in 35 Kils. of hydro-
chloric acid of 30% HCC, and of 100 litres of water, to which solution are added
40 kil. of calcium salt of the monobenzyl-o-toluidine disulphonic acid in 50 litres of
water. This solution is heated for 10 to 12 hours on the water-bath until
disappearance of the hydrol, that is to say, till a sample dissolves completely in
aminonia. The solution is mixed with sodium carbonate until it has an alkaline
reaction and is filtered from the separated calcium carbonate; the leucosalt is salted
out from the filtrate and dried.
The condensation takes place in the same way with tetraethyldiamido-benzhydrol,
as will as on employing.
example:-
10 kil. of the leucosalt from monobenzyl-o-toluidine-disulphonic acid and
tetramethyldiamidobenzhydrol are dissolved in 300 litres of water, the solution is
heated up to 60-70° C. is thoroughly stirred with the calculated quantity of peroxide
O of lead and acetic acid to which are added 6 kil. of Glauber's salt to precipitate the
lead.

page_text: "The intense blue dyestuff solution is filtered off from the sulphate of lead and the
dyestuff is salted out with common salt or the solution is brouglit to dryness in
vaouo!
The dyestuff is characterised by a great power of crystallisation. It forms copper-
coloured crystals, easily soluble in water with a blue tint.
The aqueous solution is dichroic, it has a blue-red appearance with transmitted
light and blue-green with reflected light. Ammonia and soda do not change the
solution, which turns violet when boiled with caustic soda-lye. The dyestuff, dyes
wool and silk in an acid bath blue and reflected green. The tints possess the
valuable property of retaining their green tone even in artificial light without
turning redder.
In a similar way all the above mentioned leucosalts are oxidised to dyestuffs.
There is very little difference in the properties of the separate dyestuffs.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The manufacture of blue dyestuffs of the triphenylmethane series by condensing
the sulphonic acids of mono-alkylated-o-toluidines with alkylated: diamidobenzhydrols
and oxidising the leuco-compounds thus obtained, substantially as described.
2. The dyestuff-sulphonic acids characterized by the following formule of their
carbinols:-