Improvements in the Manufacture of Azo-dyestuffs and in the Production of Fast Dyeings on Animal Fibre.
Year: 1897

page_text: Improvements in the Manufacture of Azo-dyestuffs and in the
Production of Fast Dyeings on Animal Fibre.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby declare
the nature of this invention (which has been communicated to me from abroad by
Leopold Cassella & Company, of Frankfort-on-Main, in the Empire of Germany,
Manufacturing Chemists,) to be as follows :-
Although it is known that the diazo-combination of the 2.3 amidonaphtol-6-sulpho
acid (R) may be further combined, this knowledge has not hitherto led to a
technical application probably because the azo compounds derived from the said
diazo-acid dyed on wool in an acid bath do not resist the slightest washing and are
very fugitive.
My correspondents however have discovered that surprising and technically
valuable results are obtained by treating these azo-derivatives with bichromates, new
dyestuffs resulting which in all their properties are different. from the original
dyestuffs. The shades are totally changed and what is still more important the
resulting dyestuffs are absolutely fast to light. The treatment with bichromates is
best done on the fibre itself, the dyeings thus produced being at the same time fast
to washing and milling.
100 kilos. wool are dyed under addition of bisulphate of soda with 4 kilos. of the
dyestuff resulting from diazotised 23 amidonaphtol-6-sulpho acid and beta-
naphtylamine. Thus a dark red dyeing is obtained which is treated in the same
bath with 2 kilos. of bichromate of soda, the shade is immediately changed into a
deep black, fast to milling and to light.
The same process of dyeing applied to other combinations gives for instance the
following results:

page_text: m. oxydiphenylamine
alpha naphtylamine
alpha naphtol
beta naphtol -
17 naphtylamine sulpho acid
naphtionic acid
beta naphtylaninesulpho acid
2.7 dioxynaphtaline
1.5 dioxynaphtaline
1.8 dioxynaphtaline
17 amidonaphtol
-
1.8 amidonaphtol
-
15 amidonaphtol
28 dioxynaphtaline sulpho aci
16 amidonaphtol-3-sulpho acid
1.5 amidonaphtol-7-sulpho' acid
2-8 amidonaphtol-8-6-disulpho aci
1-8 amidouaphtol-4-sulpho acid
1.8 amidonaphtol-3-sulpho acid

page_text: 14.3 parts by weight of beta-naphtylamine are dissolved with the addition of
muriatic acid at about 60° C., this solution is added to the diazocompound,
obtained as mentioned in the second example. After 24 hours the formation of
the dyestuff is terminated. The free dyestuff acid is then filtered off, dissolved in
water by the addition of soda and the dyestuff is precipitated with common salt.
It dyes wool direct red, by treatment with bichromate a deep fast black results.
The diazocompound obtained as mentioned in the second example is introduced
into a solution of 144 parts by weight of alpha naphtol in soda-lye. The thus
obtained dyestuff dyes wool direct a reddish brown, which turns into a violet black
by treatment with bichromate.

page_text: as per second example. After a few hours the dyestuff separates almost completely
in crystals, it dyes wool direct a reddish brown, which by chroming turns into a
deep black absolutely fast to milling and light.
In presence of an excess of acetate the diazocompound obtained as described in
the second example is introduced into a solution of 37 parts by weight of
1.8 diamidonaphtaline-3 6-disulphonate of sodium. After a few hours the dyestuff
separates, the blueish red shade of which is changed into a deep black by an after
treatment with bichromate.
In an analogous manner all the above combinations of the 23 amidonaphtol-6-
sulpho acid have been found to be techuically useful.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Azo-dyestuffs and in the
Production of Fast Dyeings on Animal Fibre.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby
declare the nature of this invention (which has been communicated to me from
abroad by Leopold Cassella & Company, of Frankfort-on-Main, in the Empire of
Germany, Manufacturing Chemists,) and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
Although it is known that the diazo-combination of the 2-3 amidonaphtol-6-
sulpho acid (: R:) may be further combined, this knowledge has not hitherto led to
a technical application probably because the azo compounds derived from the said
diazo-acid dyed on wool in an acid bath do not resist the slightest washing and are
very fugitive.
My correspondents however have discovered that surprising and technically
valuable results are obtained by treating these azo-derivatives with bichromates,
new dyestuffs resulting which in all their properties are different from the original
dyestuffs. The shades are totally changed and what is still more important the
resulting dyestuffs are absolutely fast to light. The treatment with bichromates is
best done on the fibre itself, the dyeings thus produced being at the same time fast
to washing and milling.
100 kilos. wool are dyed under addition of bisulphate of soda with 4 kilos. of the
dyestuff resulting from diazotised 2-3 amidonaphtol-6-sulpho acid and beta-naphtyl-
amine. Thus a dark red dyeing is obtained which is treated in the same bath with
2 kilos. of bichromate of soda, the shade is immediately changed into a deep black,
fast to milling and to light.
The same process of dyeing applied to other combinations gives for instance the
following results;

page_text: 1-6
amidonaphtol-3-sulpho acid
1-5
amidonaphtol-7-sulpho acid
2-8
amidonaphtol-3-6-disulpho
ac
1.8 amidonaphtol-4-sulpho acid
1-8 amidonaphtol-3-sulpho acid

page_text: MAAMTLE
Into a solution of 26 parts by weight of gamma amidonaphtolsulphonate of
sodium, kept alkaline by means of soda, is introduced the diazo compound obtained
as per second example. After a few hours the dyestuff separates almost completely
in crystals, it dyes wool direct a reddish brown, which by chroming turns into a 3
deep black absolutely fast to milling and light.

page_text: EXAMPLE G.
In presence of an excess of acetate the diazocompound obtained as described in
the second example is introduced into a solution of 37 parts by weight of
1.8 diamidonaphtaline-3-6-disulphonate of sodium. After a few hours the dyestuff
separates, the blueish red shade of which is changed into a deep black by an after
treatment with bichromate.
In an analogous manner all the above combinations of the 2-3 amidonaphtol-6-
sulpho acid have been found to be technically useful.
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. Treating the azo colouring matters derived from 2-3 diazonaphtol-6-sulphonic
acid with bichromates.
2. The production of fast wool dyeings by treating the azo colouring matters
derived from 2-3 diazonaphtol-6-sulphonic acid on the fibre with bichromates,
substantially as described.
3.. The azo colouring matters derived from 2.3 diazonaphtol-6-sulphonic acid,
and especially adapted for the dyeing process referred to in the second Claim, aud
the methods of manufacturing the same, substantially as described.
4. The manufacture of azo-dyestuffs and the production of fast dyeings,
substantially as described.
A