of New Colouring Matters Dyeing Cotton without Mordant.
Year: 1892

page_text: Date of Application (in United Kingdom), 30th Dec., 1892
Complete Specification Left, 30th Dec., 1892-Accepted, 4th Feb., 1893
COMPLETE SPECIFICATION.
Production of New Colouring Matters Dyeing Cotton without
Mordant.
I, JOSEPH ROHNER, Chemist, of 54 Unterer Rheinweg, Bâle, Switzerland, 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 :-
By its combination with diazo compounds, dimethylaniline sulphonic acid
furnishes colouring matters which do not present very marked qualities as dye-
stuffs; but I have found that the said sulphonic acid forms by its combination with
an equivalent molecular quantity of tetrazodiphenyl or tetrazoditolyl intermediate
products which still include a free azo group and combine with the sulphoconjugate
derivatives of the naphthylamines, furnishing with them red colouring matters
having remarkable dyeing properties.
For preparing these intermediate products, 1 operate as follows.
14 kil. of sulphate of benzidine are transformed in the known manner into the
tetrazo derivative, the solution of which is poured all at once into a solution of
11.5 kil. of metadimethylaniline sulphonate of soda. This latter solution had
previously received an addition of carbonate of soda in the quantity desired such
that, after the union of the two solutions, the whole should still shew an alkaline
reaction. The intermediate product separates in the form of a deeply coloured
precipitate. After resting for about hour the reaction is complete, and this
reaction may be expressed by the following formula
CHỌN:NG
The intermediate product obtained is soluble with difficulty in cold water and
decomposes when heated or even in the cold if long left to itself, disengaging
nitrogen.
To form the colouring matter a solution of naphthionate of soda is added after
the time mentioned to the intermediate product obtained. At the end of 24 hours
the colouring matter is formed; the solution is then heated to boiling, and the
colouring matter is precipitated by addition of sea salt, and separated by
filtration.
The colouring matter obtained has the appearance of a red powder, is easily
soluble in water and dyes unmordanted cotton in a neutral or slightly alkaline bath
a fine poppy red. This colouring matter is very sensitive, that is to say, it
presents little resistance to acids, it is coloured deep blue by acetic acid; but it
has over <<
Congo red" the advantage of furnishing more vivid tints.
го

page_text: If, instead of tetrazodiphenyl, tetrazoditolyl be employed, a colouring matter is
obtained having the same dyeing properties, but resisting acids better.
The metadimethylaniline sulphonic acid is obtained by treating dimethylaniline
with fuming sulphuric acid. By using concentrated acid and operating at low
temperature the amount obtained is approximately the theoretical aimount.
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 preparation of intermediate products, suitable for the manufacture of
colouring matters, by combining a molecule of tetrazodiphenyl or tetrazoditolyl
with a molecule of metadimethylaniline sulphonic acid.
2 The preparation of tetrazo colouring matters, red, dyeing cotton without
mordant, by the combination of intermediate products obtained by the process set
forth in the preceding claim, with naphthionic acid.
3-As new products, the new tetrazo colouring matters, as well as the inter-
mediate products suitable for the manufacture of colouring matters obtained by
the processes set forth in the two preceding claims.
Dated this 30th day of December 1892.
ABEL & IMRAY,
Agents for the Applicant.