Manufacture of Sulpho-acids of Aposafranines.
Year: 1898

page_text: Date of Application, 7th July, 1898
Complete Specification Left, 23rd Mar., 1899--Accepted, 24th June, 1899
Manufacture of Sulpho-acids of Aposafranines.
I, JOHN IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, Chancery
Lane, in the County of London, Consulting Engineer and Chartered Patent Agent,
do hereby declare the nature of this invention (as communicated to me from
abroad by The Actien Gesellschaft für Anilin Fabrikation, of Berlin, in the Empire of
Germany, Chemical Manufacturers) to be as follows:-
This invention relates to the production of new sulpho-acids of aposafranines.
Under the designation "aposafranines" my foreign correspondents understand
substances the constitution of which is represented by the following general formulae
aromatic series.
Now my foreign correspondents have discovered that by the action of normal or
acid salts of sulphurous acid, these aposafranines form in the first stage of the reaction
addition-compounds, which on heating are converted into leuco-compounds, the latter
being immediately oxidized by atmospheric air to the new aposafranine sulpho-acids.
Most probably the sulpho-group enters into the para-position to the azine-nitrogen
and the constitution of the new sulpho-acids may therefore be represented by the
following formula.
The shades obtained with the new products on wool in an acidified bath are similar
to those produced by the unsulphonated substances.
Furthermore the new aposafranine sulpho-acids are distinguished by the property
that the sulpho-group in the para-position may be easily removed by the action of
alkalies or primary amines, safraninones and safranines being formed in this way.
In order to produce the new sulpho-acids, the aposafranine, say for instance the

page_text: colouring matter known as neutral-blue, is dissolved in about ten parts by weight
of water, one part by weight of sodium bisulphite is added and the solution is heated
on the water bath.
The colour of the solution turns yellowish-brown and a precipitate begins to
separate.
By the addition of hydrochloric acid to the solution the new-sulpho-acid of the
colouring matter may be completely precipitated.
Instead of neutral blue my foreign correspondents may use other aposafranines
corresponding with the above formula or substitution products thereof.
Dated this 7th day of July 1898.
ABEL & IMRAY,
Agents for the Applicant.
Manufacture of Sulpho-acids of Aposafranines.
I, JOHN IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, Chancery Lane
in the County of London, Consulting Engineer and Chartered Patent Agent, do hereby
declare the nature of this invention (as communicated to me from abroad by The
Actien Gesellschaft für Anilin Fabrikation, of Berlin, in the Empire of Germany,
Chemical Manufacturers) 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 new sulphonic acids of aposafranines.
Under the designation "aposafranines my foreign correspondents understand
substances the constitution of which is represented by the following general
aromatic series.
Now my foreign correspondents have discovered that by the action of normal or
acid salts of sulphurous acid, these aposafranines form in the first stage of the reaction
addition-compounds, which on heating are converted into leuco-compounds, the latter
being immediately oxidized by atmospheric air to the new aposafranine sulphonic
acids. Most probably the sulphonic group enters into the para-position to the azine-
nitrogen and the constitution of the new sulphonic acids may therefore be represented
by the following formula:

page_text: The shades obtained with the new products on wool in an acidified bath are similar
to those produced by the unsulphonated substances.
Furthermore the new aposafranine sulphonic acids are distinguished by the property
that the sulphonic group in the para-position may be easily removed by the
action of alkalies or primary amines, safraninones and safranines being formed in this
way.
In order to produce the new sulphonic acids, the aposafranine, say for instance the
colouring matter known as neutral-blue, is dissolved in about ten parts by weight of
water, one part by weight of sodium bisulphite is added and the solution is heated
on the water bath.
The colour of the solution turns yellowish-brown and a precipitate begins to
separate.
By the addition of hydrochloric acid to the solution the new sulphonic acid of the
colouring matter may be completely precipitated.
Instead of neutral blue my foreign correspondents may use other aposafranines
corresponding with the above formula or substitution products thereof.
The following examples further illustrate the process.
are dissolved in 100 litres of water with addition of 10 kilos. of sodium bisulphite.
This solution is heated on the water-bath. Its colour soon changes into yellowish-
brown and at the same time a precipitate begins to separate. The aposafranine-
sulphonic acid formed is then completely precipitated by addition of hydrochloric
acid to the hot solution. The product thus obtained is insoluble in water and diluted
mineral acids and is also not dissolved by sodium carbonate.
By substituting for the aposafranine employed in Example 1, neutral blue
(Schultz & Julius, Systematic Survey of the Organic Colouring Matters, No. 389,
0 page 170) a sulphonic acid is obtained which has nearly the same properties as the
product above described.

page_text: are heated on the water-bath with 10 kilos. of sodium sulphite and 200 litres of
water. The acid gradually dissolves with yellowish brown colour. The solution
obtained is filtered and the filtrate is made alkaline by addition of sodium carbonate.
By the action of the oxygen from the air the oxidation into the disulphonic acid of
the colouring matter is effected. This acid is easily soluble in water and can be con-
verted into its sodium salt by neutralisation or can be precipitated by means of
common salt. It dyes wool in acid bath dark violet shades.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. Manufacture of sulphonic acids of aposafranines by treating aposafranines re-
presented by the following formulae :