IMPROVEMENTS IN THE MANUFACTURE OF VIOLET COLOURING MATTERS
Year: 1884

page_text: I, HERBERT JOHN HADDAN, of the firm of Herbert and Company, Patent Agents,
of 67, Strand, in the City of Westminster, Civil Engineer, do hereby declare the
nature of said Invention for IMPROVEMENTS IN THE MANUFACTURE OF VIOLET
COLOURING MATTERS," to be as follows:-
The violet sulpho-acids obtained by directly sulphonizing the benzylized violets
of commerce (as described in the specification of German Patent N° 2096) have
many drawbacks which may be more or less removed by the following treatment.
Either the ordinary commercial methyl-violet is reduced and benzyl-derivatives
are produced from the leuco bases thus obtained, which derivatives are then
sulphonized and converted into sulphonic acid dyes by oxidation.
Or the benzylised violets of commerce are reduced, their leuco-bases converted
into sulphonic acids, and the latter into sulpho-acid dyes by oxidation.
The reduction of the ordinary and of the benzylized violets is effected in the
same manner by the well known method; for instance 10 kilogrammes of colouring
matter are dissolved in 40 kilogrammes of acetic acid (of 50 per cent strength), the
solution is heated to 40 degrees Centigrade and gradually mixed with 1 kilogramme
of zinc dust, after which the violet colour will have completely disappeared.
The solution of the leuco-base thus obtained is filtered, diluted with 200 litres
of water, and mixed with 15 kilogrammes of calcined soda, whereby the base is
precipitated.
In order to purify the leuco-base, it is dissolved in diluted muriatic acid, filtered
and again precipitated by soda lye or ammonia.
If ordinary methyl-violet has been employed, the leuco-base produced from the
same will chiefly consist of Penta-methyl-leucaniline.
For benzylizing the penta-methyl-leucaniline the following treatment may be
employed:
10 kilogrammes of dry leuco-base are introduced into a closed vessel containing
a stirrer, together with 3', 7 or 10%, kilogrammes of benzylchloride and the
cquivalent quantity of sodic hydrate (that is to say 1.1, 2.2 or 3.3 kilogrammes)
Prive sl1

page_text: which ingredients have been previously dissolved in 5 times their volume of
water. By means of an oil bath the mixture is kept at a temperature of 120 to
150° Centigrades for several hours. If several molecules of benzyl-chloride have
been employed (for each unit or molecule of the product) in this process, the benzyl
group occupies the place of the hydrogen of the amido-group, as well as that of
methyl-groups, which are separated.
In order to purify the product of the reaction, the said product is treated with
aqueous vapours during several hours, dissolved in dilute hydrochloric acid, filtered,
precipitated by means of ammonia, and dried.
For sulphonizing the benzylised leuco-bases obtained in various ways, one of the
well-known methods may be employed. The oxidation of the sulpho-acids obtained
in this process may be effected by well-known methods with peroxide of lead,
peroxide of manganese, or similar oxidizing agents in acid or alcaline solution.
1001

page_text: I, HERBERT JOHN HADDAN, of the firm of Herbert and Company, Patent Agents,
of 67, Strand, in the City of Westminster, Civil Engineer, do hereby declare the
nature of said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF VIOLET
COLORING MATTERS," and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:-
:-
The economical production of the violet sulpho-acids by directly sulphonizing
the benzylized violets of cominerce (as described in the specification of German
Patent No 2096) offers not only various difficulties principally owing to the
destructive effect of the fuming sulphuric acid when at a high temperature, but
the products thus obtained have many drawbacks as regards their dyeing
properties.
In order to avoid these drawbacks, my correspondents have adopted the following
hitherto unknown methods of production.
Either the ordinary commercial methyl-violet is reduced, benzyl derivatives are
produced from the leuco-base thus obtained, which derivatives are then sulphonized
and converted into sulphonic acid dyes by oxydation. Or the benzylized violets of
commerce are reduced, their leuco-bases are converted into sulpho-acids and these
again into sulpho-acid dyes by oxidation.
As the separate processes mentioned above are carried out without difficulties,
especially the sulphonizing of the leuco-bases which have proved to be more
indifferent against the destructive effect of chemicals and of high temperatures
than the corresponding dye bases, which process takes place at a low temperature,
and as furthermore one or more benzyl groups are readily introduced into the
Pentamethylleucaniline which permits the production of mono- Di- and other
sulpho acids, moreover, as the fine blue violet dyes obtained by the oxydation of
these sulpho-acids give thoroughly satisfactory results as regards their dyeing
properties, the invention therefore constitutes a technically valuable new process
for obtaining the sulpho-acids of the benzylized derivatives of the methyl-violet.
The reduction of the ordinary and of the benzylized violets is effected in the
same manner by the well-known methods; for instance 10 kilogrammes of colouring
matter are dissolved in 40 Kilogrammes of acetic acid (of 50% strength), the
solution is heated to 40 degrees centigrade and gradually mixed with 1 Kilogramme
of zinc dust, after which the violet colour will have completely disappeared. The
solution of the leuco-base thus obtained is filtered, diluted with 200 Liters of
water, and mixed with 15 kilos of calcined soda, whereby the base is precipitated.
In order to purify the leuco-base, it is dissolved in diluted muriatic acid, filtered
and again precipitated by soda lye or ammonia.
If ordinary methyl-violet has been employed, the leuco-base produced from the
same will chiefly consist of Pentamethyl-leucaniline.

page_text: one two or three benzylgroups are to be introduced) and the equivalent quantity
of sodic hydrate (that is to say 1.1, 2.2, or 3.3 kilos) which ingredients have been
previously dissolved in 5 times their volume of water.
By means of an oil-bath the mixture is kept at a temperature of 120 to
150° Centigrades for several hours.
If several molecules or groups of benzylchloride have been employed in this
process, the benzyl occupies the place of the hydrogen of the amido-group, as well
as that of methyl-groups, which are separated.
In order to purify the product of the reaction, the said product is treated with
aqueous vapours during several hours, dissolved in dilute hydro-chloric acid, filtered,
precipitated by means of ammonia, and dried.
The sulpbonizing of the benzylized leuco-bases, obtained in various ways, may
be effected by one of the well-known methods, for instance: by the application of
hot sulphuric acid of 66°, or of cold fuming sulphuric acid (Nordhausen sulphuric
acid) during which process no destruction whatever takes place.
For instance, 10 kilogrammes of dry base are dissolved in 30 Kilogrammes of
sulphuric acid of 66°, after which fuming sulphuric acid is gradually added under
strong cooling until traces of free anhydride begin to appear which indicate that
the sulphonizing is completed.
The further treatment of the sulpho-acids is effected by the ordinary methods.
According to the number of benzyl-groups contained in the leuco-bases, mono- di-
and other sulpho-acids are produced.
The mono-sulpho acid, easily obtained in a pure state by the reduction of
commercial benzylized violet 5B, is a weak acid, and has still a semi-basic character,
being insoluble in water.
This sulpho-acid is, however, easily soluble in diluted mineral acids.
The sulpho-acids of leuco-bases containing several Benzyl groups are partly still
insoluble in water; they form, however, easily soluble alkali and lime salts.
Unlike the mono-sulpho-acid, the solutions of the salt of the sulpho-acids of the
Baid leuco-bases are for the greatest part precipitated by diluted mineral acids, the
basic character having therefore disappeared in the same.
The oxydation of the sulpho-acids obtained as described may be effected by
well-known methods, with peroxide of lead, peroxide of manganese or similar
oxidizing agents, in acid or alkaline solutions.
They are brought into the market as lime or soda salts.
The colouring mono-sulpho acid differs from the leuco-monosulpho acid chiefly
by the easy solubility of its salts in water, and by the inferior solubility of the
free-sulpho-acid in mineral acids.
The sulpho-acids of the many fold benzylized dyes, however, are easily soluble in
diluted mineral acids.
The whole of the sulpho-acid dyes obtained by this process permit the application
of acid mordants, such as sulphuric acid, for the process of dyeing.
The more benzyl groups the colouring sulpho-acid dyes contain, the more intense
blue will be their shades.
Besides the ordinary commercial methylviolet, the following violet colouring
substances may be employed for obtaining benzylized leuco-bases which are easily
sulphonized and converted into valuable violet sulpho-acid dyes.
Such substances are: the violet 5 B W of commerce which may be considered as
a Hexamethylrosanilinesalt or mono-ethyl-penta-methylrosanilinesalt, by reason of
the method of its production consisting in the ethylizing and methylizing of
violet 1 B; furthermore the commercial violet 5 R, which may be considered
substantially as a mixture of tri- and tetramethylrosaniline salts or tri and tetra-
ethylaniline salts, by reason of its technical production consisting in an incomplete
methylizing, and ethylizing of fuchsine; and lastly the methyl-ethylviolets as
obtained by the process described in the specification of German Patent N° 26016
or by the old Hofmann's method.

page_text: The reduction of these colouring substances is effected in the same manner as
that of the ordinary commercial methyl violet, but benzyl groups may be easily
introduced in the place and with separation of methyl and ethyl groups from the
previously formed leuco bases.
My correspondents have furthermore attempted to obtain similar violet sulpho-
acid dyes from fuchsine or rosaniline, or also directly from the leucaniline contained
in the fuchsine-mother liquor obtained as a bye-product in the manufacture of
fuchsine, by methylizing and ethylizing the leucaniline obtained in either manner,
and by subsequent benzylizing, sulphonizing and oxidation.
The violet sulpho-acid dyes thus produced possess the same properties as those
produced from the different violets.
In all the above mentioned leuco bases which my correspondents employ for the
production of acid violets, the presence of one or more benzyl-groups is an important
requirement, because the same are not only to be considered as the carriers of the
sulpho-groups, but they probably also determine the valuable colouring properties.
The further treatment of the above mentioned colouring substances is effected in
the manner described above.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I clain is:
1. The process for the manufacture of the sulpho-acids of leuco-bases, which
consists in introducing one or more benzyl-groups into the leuco-bases obtained by
the reduction of the unbenzylized violets of commerce hereinbefore specified, by
treating the latter with benzyl-chloride, and subsequently sulphonizing the
benzylized bases by known methods.
2. The process for the production of the sulpho-acids of leuco-bases, which
consists in sulphonizing by known methods the leuco-bases obtained by the
reduction of the benzyl-violets of commerce.
3. The process for the production of the sulpho-acids of leuco-bases, which
consists in introducing into leucaniline-besides methyl and ethyl groups-one or
more benzyl-groups, and sulphonizing by known methods the benzylised bases
resulting from such treatment.
4. The conversion of the leuco-sulpo-acids described under 1, 2 and 3, into
sulpho-acid-dyes by oxidation.