Manufacture of Sulphonic Acids of Alkyl Derivatives of Meta- amidophenolphthaleine.
Year: 1896

page_text: Date of Application, 10th Feb., 1896
Complete Specification Left, 10th Nov., 1896-Accepted, 9th Jan., 1897
[Communicated from abroad by THE FARBWERKE, vormals MEISTER LUCIUS
AND BRUNING, of Hoechst a/ Main, in the Empire of Germany, Chemical
Manufacturers.]
Manufacture of Sulphonic Acids of Alkyl Derivatives of Meta-
amidophenolphthaleine.
I, OLIVER IMRAY, of No. 28 Sonthampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention to be as follows:-
Hitherto the application of certain alkylated meta amidophenolphthaleines is
difficult, on account of their slight solubility, that is to say, their salts are stable
only in a strong acid solution; whilst in a weak acid such as is employed for dyeing
purposes, they separate the free base which is almost insoluble in water.
My foreign correspondents have made the valuable technical discovery, that the
above mentioned disadvantages may be avoided, by treating these meta amido-
phenolphthaleines with fuming sulphuric acid at a low temperature, so that they
are transformed into sulphonic acids, easily soluble in alkalies and very suitable for
dyeing purposes.
The colour hardly differs from that of the raw material.
EXAMPLE
5 kilos. of free symmetrical diethyl-m-amidophenolphthaleine or its hydrochlorate
are slowly introduced, with constant stirring, into 100 kilos. of fuming sulphuric
acid containing 10 per cent. sulphuric anhydride, at a temperature not exceeding 20° C.
Stirring is continued until all is thoroughly dissolved and until a test portion
poured into water and treated with excess of alkali no longer separates the free
diethylrhodamine base.
The sulphonic acid thus obtained, is precipitated by pouring it into water; the
precipitation is completed by the addition of salt, the acid is filtered, dissolved in
soda, and by evaporation the colouring matter is obtained in a suitable form.
The diethylrhodamine sulphonic acid is with difficulty soluble in water, more
easily soluble in alcohol with a bright yellowish red colour and a greenish yellow
fluorescence; it is insoluble in benzene, chloroform, ether and acetic ether. Its
alkali salts are easily soluble in water with a yellowish red colour and yellowish
green fluorescence.
The colouring matter is completely absorbed by wool in an acid bath and dyes
with the tint of symmetrical diethylrhodamine with brilliant fluorescence.
The corresponding sulphonic acid of triethylrhodamine is obtained in a similar
manner by treating the triethyl-m-amidophenolphthaleine with fuming sulphuric
acid. It differs from the diethylrhodamine sulphonic acid (corresponding to the
different raw material employed) by the bluer colour of its aqueous and alkaline
solutions and the bluer tints which it produces.
Dated this 10th day of February 1896.
ABEL & IMKAI,
Agents for the Applicant.

page_text: Manufacture of Sulphonio Acids of Alkyl Derivatives of Meta-
amidophenolphthaleine.
I, OLIVER IMRAY of 28 Southampton Buildings, Chancery Lane in the County
of London Chartered Patent Agent 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:-
Hitherto the application of certain alkylated meta amidophenolphthaleines is
difficult, on account of their slight solubility, that is to say, their salts are stable
only in a strong acid solution, whilst in a weak acid such as is employed for dyeing
purposes, they separate the free base which is almost insoluble in water.
My foreign correspondents have made the valuable technical discovery, that the
above mentioned disadvantages may be avoided, by treating these meta amido-
phenolphthaleines with fuming sulphuric acid at a low temperature, so that they
are transformed into sulphonic acids, easily soluble in alkalies and very suitable for
dyeing purposes.
The colour hardly differs from that of the raw material.
EXAMPLE.
5 kilos. of free symmetrical diethyl-m-amidophenolphthaleine or its hydrochlorate
are slowly introduced, with constant stirring, into 100 kilos. of fuming sulphuric
acid containing 10 per cent. sulphuric anhydride, at a temperature not exceeding 20° C.
Stirring is continued until all is thoroughly dissolved and until a test portion
poured into water and treated with excess of alkali no longer separates the free
diethylrhodamine base.
The sulphonic acid thus obtained is precipitated by pouring it into water; the
precipitation is completed by the addition of salt, the acid is filtered, dissolved in
soda, and by evaporation the colouring matter is obtained in a suitable form.
The diethylrhodamine sulphonic acid is with difficulty soluble in water, more
easily soluble in alcohol with a bright yellowish red colour and a greenish yellow
Hluorescence; it is insoluble in benzene, chloroform, ether and acetic ether. Its
alkali salts are easily soluble in water with a yellowish red colour and yellowish
green fluorescence.
The colouring matter is completely absorbed by wool in an acid bath and dyes
with the tint of symmetrical diethylrhodamine with brilliant fluorescence.
The corresponding sulphonic acid of triethylrhodamine is obtained in a similar
manner by treating the triethyl-m-amidophenolphthaleine with fuming sulphuric
acid. It differs from the diethylrhodamine sulphonic acid (corresponding to the
different raw material employed) by the bluer colour of its aqueous and alkaline
solutions and the bluer tints which it produces.
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. The herein described manufacture of sulphonic acids, of symmetrical and
unsymmetrical alkyl derivatives of meta amidophenolphthaleine by treating them
with fuming sulphuric acid.
2. The colouring matters manufactured as above set forth.
Dated this 10th day of November 1896
ABEL & IMRAY,
Agents for the Applicant.