IMPROVEMENTS IN THE PRODUCTION OF COLORING MATTERS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said Charles Denton Abel at the
Office of the Commissioners of Patents on the 31st March 1881. A com-
munication from abroad by Horace Koechlin, of Loerrach (Duchy of Baden),
and Otto Witt, of. Mulhouse (Alsace), both in the German Empire, Chemists.
CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane, in
the County of Middlesex. "IMPROVEMENTS IN THE PRODUCTION OF COLORING
MATTERS." [A communication from abroad by Horace Koechlin, of Loerrach
(Duchy of Baden), and Otto Witt, of Mulhouse (Alsace), both in the German
Empire, Chemists.]
This Invention relates to the production of blue and violet colouring matters of
a very pure and inexpensive nature by the utilisation of the re-actions that take
place when nitrosed derivatives of the tertiary aromatic amines or the phenoles, or
the bodies known as chloroquinonimides are put in presence of the alkaline or
ammoniacal salts of the phenoles, such as the phenole C6 H O, the naphtholes
Co HBO, resorcine C6H6O2, orcine C7 H8 O2, or their derivatives or homologues, or
substitution products.
The reaction is effected by adding to the mixture any reducing agent, such as
zine powder, protoxide of tin, glucose, &c.
The same coloring matters are produced with more precision and completeness
by treating with a suitable oxidising body (such as metallic chromates, ferro
cyanides, hypochlorides, or with atmospheric air), a slightly alkaline or neutral or
slightly acidulated mixture of a phenole (more particularly those above mentioned),
and any paramido derivatives, such as paraphenylenediamine, paramydodimethyl-
aniline, paramidophenol, or their derivatives or homologues. As an example of the
manner in which these coloring matters are produced, I will describe the production
of a blue coloring matter by means of the paramidodimethylaniline.
In a wooden vessel are dissolved 22 lbs. (10 kilogrammes) of nitrosodimethylaniline
hydrochlorate in 1760 pints (1000 litres) of water, at from 45° to 50° cent., to
which is added 22 lbs. of zinc powder; the mixture is agitated until the nitrosed
body is entirely reduced. The zinc is allowed to deposit, and the liquor is separated
by filtration, and the residue is washed.
In another vessel has been previously prepared a mixture of 26.4 lbs. (12 kilos.)
of pure phenole, 26-4 lbs. of caustic soda lye at 1.29 specific gravity (38° Beaumé),

page_text: 352 pints (200 litres) of water, and 22 lbs. (10 kilos.) of bichromate of potass. This
mixture is added to the solution of paramidodimethylaniline obtained as above
described, and commercial acetic acid is slowly added. The coloring matter is
produced instantaneously, and is completely precipitated as soon as the liquid, which
is at first alkaline, becomes slightly acid. The precipitate is separated by filtration
and washed, and is then ready for the market, either in the form of paste or of
powder. Instead of preparing the coloring matters as separate bodies as above
described, they may be produced directly on fabrics; by this means colours are
obtained that do not fade and that stand washing. Of the several processes for
producing the blue colouring matter on textile fabrics, the most advantageous are
the following:
1. The fabric to be printed upon is impregnated with an alkaline solution of
naphthole, and after drying it is printed upon with a thickened solution of
nitrosodimethylaniline hydrochlorate, to which was added a reducing substance,
such as protoxide of tin, glucose, &c., that will only act in presence of an alkali;
on then steaming the fabric the color will appear.
2. The fabric is treated with a solution of a reducing agent, such as glucose, and
is printed upon with a thickened solution of a mixture of nitrosodimethylaniline
and naphthole-sodium or potassium; the color appears on steaming.
3. The bleached fabric is printed upon with a thickened solution of a mixture
of paramidodimethylaniline and naphthole sodium, is then steamed, and is passed
through a solution of bichromate of potass and washed, the colour appearing in the
bichromate bath.
I am aware that Witt and Meldoe have described a series of colouring matters
obtained by the action of acetic solutions of phenoles upon nitrosodimethylaniline
under ebullition; these are entirely different from those above described.