Producing Diazo Salts in a Durable form.
Year: 1897

page_text: Producing Diazo Salts in a Durable form.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby declare
the nature of this invention: (which has been cominunicated to me from abroad by
Leopold Cassella and Company, of Frankfort on Main, in the Empire of Germany,) to
be as follows:-
Various ways have already been tried to solve the problem of producing diazo
combinations in a durable form in order to bring them in such a state on the market.
Products of this kind have been obtained by transforming diazo bodies into nitro-
Bamine derivatives by the action of caustic alkalis, or by evaporating diazo solutions
in a vacuum, or by producing metallic double salts of diazo bodies, or their difficultly
soluble naphtalene sulphonic salts. Some of these processes have been applied to the
most important diazo compound used for dyeing and printing, viz. diazopara-
nitraniline. These preparations however have many defects; some of them can only be
made in the form of a paste, some contain injurious admixtures, as for instance
chloride of zinc, and all of them do not yield clear solutions, rendering costly filtra-
tions necessary.
My correspondents have discovered a process which in an astonishingly simple and
perfect manner solves this problem. They diazotise the bases dissolved in concen-
trated sulphuric acid with gaseous nitrous acid and, after the diazotation has been
completed, they add a quantity of neutral sulphates, such as calcinated Glauber's
Balt, equivalent to the quantity of sulphuric acid applied, so that a dry mixture of a
sulphate of the diazo combination and inorganic bisulphates results. The operation
may be effected by either introducing the nitrous acid into the sulphuric acid solution
of the base or the base into the solution of nitrous acid in sulphuric acid.
A stream of nitrous acid is introduced into 80 parts by weight of sulphuric acid
until 10 parts by weight of the former have been absorbed. Then 30 parts by weight
of paranitraniline are gradually introduced whilst cooling. To the clear and colour-
less solution of the diazo-compound 120 parts by weight of calcinated Glauber's salt
are added.
After a short time the paste becomes solid. It is then broken into lumps
which are brought into the market. It yields a perfectly clear solution in water and.
is not affected by blows or heat.
In an analogous manner preparations of other diazo and tetrazo bodies can be
produced.

page_text: I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby deolare
the nature of this invention (which has been communicated to me from abroad' by
Leopold Cassella and Company, 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 :-
•
Various ways have already been tried to solve the problem of producing diazo
combinations in a durable form in order to bring them in such a state on the
market. Products of this kind have been obtained by transforming diazo bodies into
nitrosamine derivatives by the action of caustic alkalis, or by evaporating diazo
solutions in a vacuum, or by producing metallic double salts of diazo bodies, or their
difficultly soluble naphtalene sulphonic salts. Some of these processes have been
applied to the most important diazo compound used for dyeing and printing, viz.
diazoparanitraniline. These preparations however have many defects; some of them
can only be made in the form of a paste, some contain injurious admixtures, as for
instance chloride of zinc, and all of them do not yield clear solutions, rendering costly
filtrations necessary.
My correspondents have discovered a process which in an astonishingly simple and
perfect manner solves this problem. They diazotise the bases dissolved in concentrated
sulphuric acid with gaseous nitrous acid and, after the diazotation has been completed,
they add a quantity of neutral sulphates, such as calcinated Glauber's salt, equivalent
to the quantity of sulphuric acid applied, so that a dry mixture of a sulphate of the
diazo combination and an alkaline bisulphate results. The operation may be effected
by either introducing the nitrous acid into the sulphuric acid solution of the base or
the base into the solution of nitrous acid in sulphuric acid.