Improvements in the Manufacture of Colouring Matters.
Year: 1892

page_text: Date of Application, 21st Jan., 1892
Complete Specification Left, 12th Feb., 1892-Accepted, 2nd Apr., 1892
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Messieurs WIRTH & Co., of Frankfort-on-
the-Main, in the Empire of Germany, acting as Agents of A. Leonhardt & Co.,
of Mühlheim, near Frankfort-on-the-Main, in the Empire of Germany,
Manufacturers.]
Improvements in the Manufacture of Colouring Matters.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, do hereby
declare the nature of this invention to be as follows:-
I have found that the bluish red basic colouring matters derived from dialkylmeta-
amidophenols (such as the rhodamines produced from phthalic acid or succinic
acids, the pyronines and so forth) by acting on them with energetic oxidizing
agents by preference with permanganate, are transformed into other colouring
matters of a more yellowish tint, the solutions of which generally show a greenish
fluorescence.
Instead of using in this process the dye-stuffs themselves, their products of
reduction can be used. In this case in the first stage the bluish red dye stuffs are
produced and these by further treatment with oxidizing agents are transformed
into the more yellowish red products.
It is possible by varying the quantities of the employed oxidizing agent, to turn
the original bluish red more or less into yellowish red.
The dye-stuffs thus obtained resemble in their properties those derived from
monoalkylmetaamidophenols. They are specially adapted for dyeing mordanted
as well as unmordanted cotton.
Dated this ct day of T1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Colouring Matters.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, 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:
I have found that the pink to bluish red basic colouring matters derived from
dialkylmetaamidophenols (such as the rhodamines of dialkylmetaamidophenol or
dialkylmetaamidocresol and phthalic acid or derived from succinic acid or formic
acid, or the pyronines or the benzeines) when treated with strong oxidizing agents
are transformed into other colouring matters of a more yellowish red tint.
As an oxidizing agent, permanganate of potassium has given the best results but
per-oxide of manganese or of lead together with dilute sulphuric acid in the heat
would also do.
Instead of using in this process the bluish red colouring matters themselves,
their products of reduction (or leuco-compounds) may be employed. In this case
the leuco-compounds are first transformed into the corresponding colouring matters
which by further oxidation yield yellowish red compounds.

page_text: It is possible thus, by varying the quantities of the oxidizing agent employed
to change the original bluish red tints more or less into yellowish red ones.
The colouring matters thus obtained are of a basic nature forming salts only
with acids. They dissolve in water or spirit yielding scarlet solutions showing a
brilliant greenish fluorescence. They are principally adapted for dyeing and
printing mordanted or unmordanted cotton and silk, the latter dyed therewith
showing a yellowish fluorescence.
The following example will show the manner in which this invention may be
advantageously carried out :-
8 kilos. of rhodamine derived from succinic acid are dissolved in 400 litres of
water and 20 litres of acetic acid, and to the cold solution a solution of 4 kilos. of
permanganate of potassium in 100 litres of water is gradually added, the mass
being well stirred during the addition of the oxidizing agent. The oxidation is
already effected in the cold. The liquid is then boiled and filtered and when cooled
down (after renewed filtration if necessary) the colouring matter is precipitated
with chloride of zinc and common salt. If in this process I employ less
permanganate I obtain a more bluish red product. If I employ too much of the
oxidizing agent the whole of the dyestuff will be gradually destroyed.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
· by my foreign correspondents, I declare that what I claim is :-
First. The process of transforming the bluish red dyestuffs derived from
dialkylmetaamidophenols as herein before mentioned, or their corresponding leuco-
compounds, into other colouring matters of a more yellowish red tint, this process
consisting in an oxidation, substantially as set forth.
Second. The yellowish red colouring matters produced substantially as set
forth.
Dated this 12th day of February 1892.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.