Processes for the Manufacture of Colouring Matters.
Year: 1890

page_text: CUM LEIN DI ECIFICATION.
Processes for the Manufacture of Colouring Matters.
I, THEODOR PETERS, Manufacturing Chemist, of Chemnitz, Saxony, do hereby
declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
During their investigations on the azo-phenin of the naphthalene series, that is,
the anilido-naphtho-quinone-anil, Messrs. Fischer and Hepp obtained a red basic
colouring matter insoluble in water and in alkalies (Berl. Ber. 21, 2621). This
dyestuff is formed from all the various naphthalene-derivatives, which can be con-
verted into anilido-naphtho-quinone-anil by melting them with anilin and its hydro-
chloride at temperatures ranging between 100 degrees and about 160° Centigrade.
English sulphuric acid converts the dyestuff exclusively into a monosulphonic acid
(also called monosulpho-acid), but stronger sulphonating agents form higher sulpho-
compounds, namely a di- and tri-sulphonic acid (German Patent No. 45370 of the
Badische Anilin and Soda-fabrik).
The naphthalene-derivatives which have hitherto been employed for the formation
of the anilido-naphtho-quinone-anil or of the red dyestuff, resemble each other so
far, as they are all free from sulpho-groups. Now, I have found, on the one hand,
that a whole series of the same in a sulphonated condition, on being fused together
with aniline, behave in a manner quite analogous to the unsulphonated raw materials,
in so far as they yield the same basic product; but on the other hand, if the sulpho-
group adheres to a certain place of the naphthalene nucleus, the resulting mass
(hereinafter called the "melt") has the character of an acid, and more particularly
that of a sulpho-acid, which enables it to form salts with bases and to dissolve
easily in dilute alkali-solutions. The sulpho-derivatives applicable for producing
this effect are the nitroso-beta-naphthol-monosulphonic acid of Meldola, the nitrosised
beta-naphthol-disulphonic acid R and G, the nitroso-compound of the phenyl-beta-
naphthylamine-sulphonic acid (position of the substitute according to the diagram of
Erdmann NH. C, H, SO, OH = 26), and also the azo-compounds which result
from the combination of the diazo-bodies (or of the tetrazo-bodies) of the benzene-
series with Schäfer's beta-naphthol-monosulphonic acid, or with the beta-naphtol-
disulphonic acids R and G, or with Bronner's beta-naphthylamine-monosulphonic
acid, and with their derivatives obtained by substituting alkyls, phenyl or tolyl for
the amido-group, or with Laurent's alpha-naphthylamine-sulphonic acid (Witt's
naphthalidine-sulphonic acid NH, SO, OH = 15) and with the alpha-
naphthol-alpha-sulphonic acid corresponding to the latter (OH: SO, OH = 1 : 5).
There is no apparent difference between the melt obtained by means of naphthol-
disulphonic acid R and G and that obtained by means of the monosulphonic-acid.
The bodies obtained by us and which are soluble in alkalis, differ essentially from
the above mentioned sulpho-acid of the red basic dyestuff, by the fact, that they
can be very easily converted into a highly sulphonated product by means of English
sulphuric acid, which product is much more soluble in cold water, than the di- or
tri-sulphonic acid obtained from the said monosulphonic acid by intense sulphonation
with fuming sulphuric acid and similar agents; and the colour produced on animal
fibre by my new dyestuff's is also of a much more violet shade.
:
The actual process of manufacture of my new dyestuff may be described as
follows:-
7.5 kilogrammes of Meldola's nitroso-naphthol-monosulphonic acid (or instead of
it, the same quantity of one of the compounds mentioned above) are heated with
8 kilogrammes of hydrochloride of aniline and 30 kilos. of oil of aniline for about
4 hours to a temperature slightly below 100 degrees Centigrade, during which time

page_text: an energetic reaction takes place and the mass assumes a blueish red colour. Sub-
sequently, the temperature is gradually raised to 125°-130°. Also during the
second stage the beginning of a reaction is clearly noticeable. The process may be
considered as completed, if a sample of the product resulting from the reaction gives
with concentrated sulphuric acid a purely green solution.
To heat the mass longer, or to raise the temperature would promote the formation
of resinous bye-products and should therefore be avoided. The relative quantities
of the ingredients mentioned above need not be strictly observed, as a variation
affects only the speed of the reaction.
The melt thus obtained is heated with steam, in order to remove any aniline,
that may have remained intact, after which it is washed with water to remove the
remnant of aniline salt.
The crude melt treated in this manner is a dark mass with a greenish-yellow
metallic lustre, which appears crystalline, if the operation has been carried out very
successfully. It is, however, always interspersed with other bodies, for instance
with substances of a resinous nature, and must be subjected to a further cleaning
process. This may be done by extraction, for instance with benzene or other hydro-
carbons and recrystallisation of the residue from alcoholic solution (strength
96 per cent. of absolute alcohol), but it is more advantageous to utilize for this
purpose the fact, that by adding common salt to the solution of the melt in dilute
soda lyc, the soda-salt of a sulphonic acid, very probably that of a monosulphonic
acid is precipitated, while the constituents which must be considered as impurities,
remain in solution.
For instance, 5 kilos. of the pulverised melt are boiled with 50 litres of water
and 25 litres of soda-solution having a specific gravity of 1-32 (equal to 35° Baumé)
until the whole is dissolved, subsequently the liquid is filtered and a small quantity
of saturated solution of common salt added to the filtrate. The result is the forma-
tion of blueish-grey flakes, which are separated from the dark green liquor by
filtration. By repeated solution and precipitation I obtain a perfectly pure soda
salt, from which the free sulphonic acid may be precipitated by dilute mineral
acids. This sulphonic acid is very sparingly soluble in water, but more easily
in alcohol, from which it may be obtained in the shape of brilliant bronze
coloured crystals.
It possesses only in a low degree the nature of a dye, but the higher sulphonated
product obtainable from the same is a much stronger dye. It is very easily
produced by treating the crude mass relieved of aniline, or the purified soda salt,
or the free acid, with English sulphuric acid at 60 to 80 degrees, Centigrade.
5 kilos. of the crude fused mass, or of the purified products are dissolved in
20 kilos. of English sulphuric acid, with constant stirring, and subsequently heated
over a water bath until a sample forms in cold water a clear solution. The
sulphonating mixture is poured into the twentyfold quantity of water, and either
the sulphonic-acid separated from the sulphuric acid by means of lime-salts, or exact
neutralization is produced by means of an alkali and the alkali-salts of the organic
acids thus formed are precipitated by means of common salt. Especially the
ammonia-salt is beautiful. By recrystallisation it is obtained in the shape of
crystals which shine with a metallic chestnut colour, and can be easily dissolved in
an abundance of water with an intense blueish-red colour. In an acidulated bath
they impart to animal fibre a fine reddish-violet shade.
The same effect, as with English sulphuric acid, may be produced with other
sulphonating agents.
The beautiful reddish-violet dye may be easily converted into one with a purely
red shade by again sulphonating it at a low temperature. This is effected by
treating it, either in the shape of its soda-salt or in the shape of the free sulphonic-
acid-both in a very pure and perfectly dry state-with fuming sulphuric acid
(oleum) maintained at a low temperature.
For this purpose, I may for example, take. 5 kilos of the reddish-violet dye
(either as free sulphonic acid or as sodium salt) in a dry condition and gradually

page_text: introduce it into 15 kilos. of oleum containing 20 to 25 per cent. of free SO3,
care being taken, that the temperature does not exceed 50-60°. When the
whole quantity has been introduced, the mixture is left to itself for a considerable
time. Subsequently I take a sample and ascertain, whether, on being dropped
upon ice, it produces a brick-red deposit, and also whether it produces in actual
dyeing a purely red colour. If this is the case, I pour the whole sulphonating
mixture upon ice, collect the brick coloured deposit on a filter and relieve it of
acid, by washing with a solution of common salt. Subsequently I dissolve it at
high temperature in 100 litres of water and add 75 to 100 kilos. of saturated
solution of salt. On cooling, the new red dye-stuff separates in a granular
crystalline condition. When ground to a paste in a suitable manner, it shines with
a chocolate colour.
a
In cold water it dissolves very easily with red colour, which borders on the blue.
This slightly blueish tint disappears on the addition of a small quantity of mineral
acid, the red becomes stronger and yellowish. On the other hand, a slight addition
of alkali to the aqueous solution, changes the colour at once to a pure blueish-
violet. This behaviour is very characteristic for my new colouring inatter, which
in other respects has the properties of a sulphonic acid, like the reddish violet
dye from which it has been produced.
From slightly alkaline solution its soda-salt can only be precipitated with great
difficulty (in contradistinction to the reddish violet dye) and never completely. The
free sulphonic acid crystallises from concentrated aqueous solution in gold coloured
scales, and resembles in this respect, the reddish-violet dye, and also as regards
the green colour of its solution in sulphuric acid of 66° Baumé.
Applied on wool in an acid bath, the new dye-stuff' produces a purely red and
flaming colour, which is quite fast.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is―
1. Process for obtaining an alkali-soluble product, which consists in fusing-
Meldola's nitroso-betanaphthol-monosulphonic acid or
Nitroso-betanaphthol-disulphonic acid R and G, or
Nitroso-compound of phenyl-betanaphthylamine-sulphonic acid (NH. C. H.:
SO, OH 2: 6), or
Benzene-azo-betanaphthol-monosulphonic acid (from Schäfer's betanaphthol-
monosulphonic acid (OH SO, OH=26) or
Benzene-azo-betanaphthol-disulphonic acid R and G, or
:
Benzene-azo-betanaphthylamine-sulphonic acid (NH, SO, OH - 2 : 6) or
Benzene-azo-phenyl-betanaphthylamine-sulphonic acid (NH. C, H, SO, OH:
2: 6) or
=
=
Benzene-azo-naphthalidin-sulphonic acid (NH, SO, OH 1:5) or
Benzene-azo-alphanaphthol-alphasulphonic acid (OH: SO, OH = 1:5) with
aniline or hydrochloride of aniline.
2. The manufacture of a multi-sulphonated product having the character of a
reddish violet dye, which consists in converting any of the alkali-soluble products
specified under claim (1) by means of English sulphuric acid or other suitable
sulphonating agents.
3. Process for obtaining a pure red dye, which consists in treating the reddish
violet dye mentioned in claim (2) with fuming sulphuric acid (oleum) or similar
sulphonating agents.
Dated this 30th day of December 1890.
THEODOR PETERS.
By Fairfax & Wetter,
433, Strand, London, Agents.