Year: 1896

page_text: Date of Application, 3rd June, 1896
Complete Specification Left, 2nd Mar., 1897-Accepted, 17th Apr., 1897
I, SYDNEY PITT, of Sutton in the County of Surrey, do hereby declare the
nature of this invention (which has been communicated to me from abroad by
Leopold Cassella and Co., of Frankfort on Main, in the Empire of Germany) to
be as follows:-
This invention relates to the production of certain polyazo dyestuffs by aid of
the re-diazotised intermediate bodies which result from the combination of
one molecule of a tetrazo body and the a₁ ß, or the a₁ 3, naphtylaminesulpho acid.
The researches of my correspondents have shown that in those tetrazo-azo-
derivatives of the constitution
II N N P -N-N-C10H¸(SO₂H) —
the diazo group I reacts very much more strongly than the diazo group II.
This knowledge renders it possible to form combinations which are not obtainable
by direct diazotation and combination of mixed disazo dyestuffs deriving from
aßs (a) naphtylaminesulpho acids. It has been ascertained that after the
diazo group I is saturated, the diazo group II can be combined with amines which
are themselves changed by the influence of nitrous acid and which would therefore
have been affected by the re-diazotation, if they had previously been combined
with the paradiamine. Amongst the thus constituted azo-derivatives the brown
dyestuffs which result if the diazo group I is combined with phenol and the diazo
group II with chrysoidines or dyestuffs belonging to the class of vesuvine or
Bismark brown are of special technical value.
Example. 18.4 parts by weight of benzidine are tetrazotised and combined with
22-3 parts by weight a naphtylamine-6-sulpho acid, the intermediate body is
diazotised again in muriatic acid solution by aid of 7 parts by weight of nitrite of
soda; the solution is then made weakly alkaline by means of carbonate of soda
and 94 parts by weight phenol are immediately added. After 5 to 10 minutes
this is absorbed, and after muriatic acid has been added until the solution reacts
slightly acid, a solution of 40 parts by weight Bismark brown is introduced. The
dyestuff forms immediately. It dyes unmordanted cotton a full brown which is
distinguished by its fastness to light.
Analogous products are obtained by applying other paradiamines such as tolidine,
dianisidine, diamido diphenylamine.
In the place of Bismark brown the following substances can be for instance used
to advantage, viz. :-
The dyestuffs derived from m. phenylenediamine and the diazo compound
Of sulphanilic acid which dye unmordanted cotton yellowish brown,
"naphtionic acid
"
وو
"
23
"
cinnamon brown,
yellowish brown,
وو
amido-salicylic acid
"gamma-amidonaphtolsulpho acid which dye unmordanted cotton,
reddish brown,
وو
" amidonaphtoldisulpho acid H which dye unmordanted cotton,
dark brown.

page_text: abroad by Leopold Cassella and Co. of Frankfort on Main, in the Empire of
Germany) and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
This invention relates to the production of certain polyazo dyestuffs by
aid of the re-diazotised intermediate bodies which result from the combination
of one molecule of a tetrazo body and the a₁ ßs or the a₁ ß, naphtylaminesulpho
acid.
The researches of my correspondents have shown that in those tetrazo-azo-
derivatives of the constitution
II N N
P-N-N-C₁H,(SO,H) - NN-I
the diazo group I reacts very much more strongly than the diazo group II.
This knowledge renders it possible to form combinations which are not obtainable
by direct diazotation and combination of mixed disazo dyestuffs deriving from
a Ba (a) naphtylamine sulpho acids. It has been ascertained that after the diazo
group is saturated, the diazo group II can be combined with amines which are
themselves changed by the influence of nitrous acid and which would therefore have
been affected by the re-diazotation, if they had previously been combined with the
paradiamine. Amongst the thus constituted azo-derivatives the brown dyestuffs
which result if the diazo group I is combined with phenol and the diazo group II
with chrysoidines or dyestuffs belonging to the class of vesuvine or Bismarck brown
are of special technical value.
Example. 184 parts by weight of benzidine are tetrazotised and combined with
22-3 parts by weight a, naphtylamine-6-sulpho acid, the intermediate body is
diazotised again in muriatic acid solution by aid of 7 parts by weight of nitrite of
soda; the solution is then made weakly alkaline by means of carbonate of soda
and 9-4 parts by weight phenol are immediately added. After 5 to 10 minutes
this is absorbed, and after muriatic acid has been added until the solution reacts
slightly acid, a solution of 40 parts by weight Bismarck brown is introduced. The
dyestuff forms immediately. It dyes unmordanted cotton a full brown which is
distinguished by its fastness to light.
Analogous products are obtained by applying other paradiamines such as tolidine,
dianisidine, diamidodiphenylamine.
In the place of Bismarck brown the following substances can be for instance used
to advantage, viz. :-

page_text: 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. Producing polyazo dyestuffs by combining the re-diazotised intermediate
bodies which result from the combination of one molecule of a tetrazo body with
one molecule of a ß, or a B. naphtylaminesulpho acid with one molecule of phenol
and one molecule of a metadiamine, chrysoidine, Bismarck brown or vesuvine
substantially as described.
2. The new coloring matters which may be obtained as above set forth.
Dated this 17th day of Februame 1807
SYDNEY PITT.