Improvements in the Manufacture of Colouring Matters.
Year: 1891

page_text: Date of Application, 28th Oct., 1891
Complete Specification Left, 27th July, 1892-Accepted. 27th Aug.
1892
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Messrs. WIRTH & Co., of Frankfort on the
Main, in the Empire of Germany, acting as Agents of A. Leonhardt & Co.,
of Muhlmeim, 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:-
Tetraalkyldiamido-diphenylmethan when nitrated in a solution of sulphuric acid
is converted into a dinitro-compound which by reduction yields the diamido-deriva-
tive. This diamido-derivative can also be produced by the action of formaldehyde
or metaamido-dialkylaniline. Similar diamido derivatives result from the action
of other aldehydes (as for instance benzaldehyde) on metaamido dialkylaniline or
its homologues.
Such amido-derivatives when treated with nitrous acid yield oxy-compounds
under development of nitrogen. These oxy-compounds can be converted into
basic blueish red pink colouring matter either by a direct oxydation or by
heating them with a condensing agent such as sulphuric acid followed by an
oxydation.
Dated this 28th day of October 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, 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 per-
formed to be particularly described and ascertained in and by the following
statement:-
This invention relates more particularly to the subject matter of my former
Letters Patent No. 13217/89 and consists of a modified process of producing the
oxides claimed in the fourth claim of the said former Patent.
Instead of producing the oxides (as is stated in the said Patent) by treating
tetraalkyldiamidodioxydiphenylmethan with dehydrating agents, I now treat tetra-
alkyltetramidodiphenylmethan of the formula
with two molecules of nitrous acid. I thus obtain very unstable diazo-compounds
which decompose even at a low temperature and form under development of
nitrogen, oxy-compounds which are identical with the oxides mentioned in the said
former Patent No. 13217". These oxy-compounds can be oxidized into basic
Paine Rd1

page_text: pink colouring matters identical with the dyestuffs described and claimed in the
said former Patent.
or
The best results are obtained by employing tetramethyltetramidodiphenylmethan
tetraethyltetramidodiphenylmethan.
Example 2-8 kilos of tetramethyltetramidodiphenylmethan are dissolved in
40 kilos. of concentrated sulphuric acid and 250 litres of water, and to this solution,
a solution of 1.4 kilos of nitrite of sodium is gradually added. (This process may
be carried out, not only at a low temperature but at any temperature say up to
about 40° C. without materially altering the result).
When all the diazo-compound is decomposed the solution contains the oxy-
compound, which may be isolated by adding to the liquid an excess of caustic soda
lye, the oxy-compound being insoluble in alkaline liquids. But for the production
of the pink dyestuffs it is not necessary to isolate the oxy-compound, it is preferable
to oxidize directly the acid solution containing the oxy-compound. This oxidation
is carried out in a similar way to that indicated in the said Patent No. 132178°.
For instance, I add to the acid solution 14 kilos. of ferric chloride solution of 30%
and bring the fluid to the boiling point with steam, when the colouring matter
rapidly forms. After cooling down, the dyestuff is precipitated with common salt
and is purified by dissolving and precipitating again with common salt and
chloride of zinc. By boiling down the solution of the oxy-compound and oxydizing
it afterwards, I obtain a similar colouring matter but of a more yellowish shade.
In a similar way tetraethyltetramidodiphenylmethan can be converted into the
corresponding oxides and colouring matters.
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 I make no claim to the oxidation of the
oxy-compounds, and the colouring_matters obtained by such oxidation as this is
already claimed in the said former Patent No. 1321789 but what I claim is :-
First. The herein described process of transforming tetramethyl and tetra-
ethyltetramidodiphenylmethan into oxy-compounds by treating them with nitrous
acid substantially as hereinbefore described.
Second. The oxy-compounds prepared from tetramethyl or tetraethyltetramido-
diphenylmethan and nitrous acid substantially as hereinbefore described.
Dated this 27th day of July 1892.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.