Year: 1888

page_text: Date of Application, 4th Jan., 1888
Complete Specification Left, 11th Sept., 1888
Complete Specification Accepted, 12th Oct., 1888
1. CHARLES DENTON ABEL of No. 28 Southampton Buildings, Chancery Lane in
the County of Middlesex, Consulting Engineer and Patent Agent do hereby declare
the nature of this invention to be as follows:-
My correspondents have found that in the sulphonizing of Diphenylamine described
in Berliner Berichten VI 1513, a mixture of two isomerical Mono-sulpho-acids
occurs.
The Monosulpho acid described by Merz and Weith was obtained by the continued
heating of 5 parts of Diphenylamine with G parts of sulphuric acid to from 150
to 170° Cent., with undecomposed base and disulpho-acid. The presence of the latter
impedes the separation of the mono-sulpho-acid considerably; in addition there are
formed with the said process resinous and colored byeproducts, with partial destruction.
of the diphenylamine.
By adopting different portions and temperatures my correspondents have been able
to transform the said reaction into a practically advantageous process, with complete
avoidance of the formation of disulpho-acids 100 kilog. diphenylamine and 50 Kilog.
sulphuric acid at 66° are heated for from 12 to 24 hours to from 140 to 150° Cent.
The reaction takes places best at this temperature, a higher heat being of no
advantage.
The mass, which is of glossy appearance when cold, is exhausted with hot water,
whereby the sulpho acids pass into solution, the unattacked diphenylamine is recovered
as a crystalline cake, and can serve in further operations in the place of a fresh base.
The sulpho-acids are transformed in the known manner into their barium, Calcium,
or sodium salts; the operation can also be carried out in such manner that the melt
is extracted directly with the bicarbonate of soda or soda lye necessary for the
neutralization.

page_text: A. SEPARATION OF THE SODA SALTS BY MEANS OF ALCOHOL.
The soda salts of the sulpho acids are exhausted at boiling heat with alcohol
of 90 to 95 per cent. and are filtered hot; as residuum remains (eventually together
with sulphate) the salt of diphenylamine ẞ monosulphoacid. From the solution is
obtained by crystallisation or distilling off of the spirit, the a monosulphoacid.
B. SEPARATION OF THE ACIDS FROM AQUEOUS SOLUTIONS.
The separation by fractional crystallisation is more tedious and in so far imperfect
that it is only possible to obtain the greater part of the a acid free from the ẞ acid.
For this purpose the baryta or lime salts are evaporated to such an extent that
an energetic separation of crystals commences, after which the mass is allowed
to cool.
The crystals separated from the lye consist mainly of salts of the a monosulpho-
acid. On further concentration of the lye, compounds already crystallise out; by
suitably combining and recrystallising the separate fractions, the principal part of
the a acid may be approximately isolated.
In the place of the baryta and lime salts may be employed with advantage the soda
salts the solution thereof is concentrated until a sample thereof solidifies on a
glass rod, and it is allowed to cool. The crystalline mass obtained is either pressed
or separated by centrifugal action.
It contains mainly a mono sulphonate of soda, and represents about 60 to 70 per
cent. of the total quantity. The complete separation of the acid remaining in the
mother lye is effected as described under A.
The two acids are characterized not only by their different degree of solubility
but in particular by their behaviour to the diazo compounds. The diphenylamine
monosulpho acid designated as a acid reacts, contrary to the ẞ acid, easily with diazo
compounds, as for instance diazobenzole, the coloring matters produced possess
increased powers of crystallisation, as also different tints from and greater coloring
power than the analagous derivatives of the ẞ acid.
With some reagents the said acids shew a different behaviour from that indicated
by Merz and Weith (Berl. Ber. VI 1514) for their diphenylamine sulpho acid.
The acids produced by me dissolve in concentrated sulphuric acid with very slight
brown coloration. Oxidizing agents, such as chloride of iron, chloride of potash,
and permanganate, color the solutions of the free acids a uniform dirty green.
The solutions assume the same color on standing in the air for a length of time.
The two above described monosulphoacids of diphenylamine are intended to be
formed into coloring matters, either separately or mixed, by combination with diazo
and tetrazo compounds.
Dated this 4th day of January 1888

page_text: COMPLETE SPECIFICATION.
Process for the Production of Sulpho-acids of Diphenylamine.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery Lane,
in the County of Middlesex, Consulting Engineer and Patent Agent, do hereby
declare the nature of this invention and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement :-
My correspondents have found that in the sulphonizing of Diphenylamine described
in Berliner Berichten VI, 1513, a mixture of two isomerical mono-sulpho acids
occurs.
The monosulpho acid described by Merz and Weith was obtained by the continued
heating of 5 parts of Diphenylamine with 6 parts of sulphuric acid to from 150
to 170° Cent. with undecomposed base and disulpho acid. The presence of the latter
impedes the separation of the mono-sulpho acid considerably; in addition there are
formed with the said process resinous and coloured bye products, with partial
destruction of the diphenylamine.
By adopting different portions and temperatures my correspondents have been able
to transform the said reaction into a practically advantageous process with complete
avoidance of the formation of disulpho-acid 100 kilog. diphenylamine and 50 kilog.
sulphuric acid at 66° are heated for from 12 to 24 hours to from 140 to 150° Cent.
The reaction takes place best at this temperature, a higher heat being of no
advantage.
The mass, which is of glassy appearance when cold, is exhausted with hot water,
whereby the sulpho acids pass into solution; the unattacked diphenylamine is
recovered as a crystalline cake, and can serve in further operations in the place of a
fresh base. The sulpho-acids are transformed in the known manner into their barium,
calcium, or sodium salts; the operation can also be carried out in such manner that
the melt is extracted directly with the bicarbonate of soda or soda lye necessary for
the neutralization.
A. SEPARATION OF THE SODA SALTS BY MEANS OF ALCOHOL.
The soda salts of the sulpho acids are exhausted at boiling heat with alcohol of 90
to 95 per cent. and are filtered hot as residuum remains (eventually together with
sulphate) the salt of diphenylamine ẞ monosulpho acid. From the solution is obtained
by crystallization or distilling off of the spirit, the a monosulpho acid.
B. SEPARATION OF THE ACIDS FROM AQUEOUS SOLUTIONS.
The separation by fractional crystallisation is more tedious and in so far imperfect
that it is only possible to obtain the greater part of the a acid free from the ẞ acid.
For this purpose the baryta or lime salts are evaporated to such an extent that
an energetic separation of crystals commences, after which the mass is allowed

page_text: The crystals separated from the lye consist mainly of salts of the a monosulpho
acid. On further concentration of the lye compounds already crystallise out; by
suitably combining and recrystallising the separate fractions, the principal part of
the a acid may be approximately isolated.
:
In the place of the baryta and lime salts may be employed with advantage the soda
salts the solution thereof is concentrated until a sample thereof solidifies on a glass
rod, and it is allowed to cool. The crystalline mass obtained is either pressed or
separated by centrifugal action.
It contains mainly a mono sulphonate of soda and represents about 60 to 70 per
cent. of the total quantity. The complete separation of the acids remaining in the
mother lye is effected as described under A.
The two acids are characterized not only by their different degree of solubility but
in particular by their behaviour to the diazo-compounds. The diphenylamine mono
sulpho acid designated as a acid reacts, contrary to the 3 acid, easily with diazo
compounds, as for instance diazo benzole, the coloring matters produced possess
increased powers of crystallisation, as also different tints from and greater coloring
power than the analagous derivatives of the 3 acid.
With some reagents the said acids shew a different behaviour from that indicated
by Merz and Weith (Berl. Ber. VI 1514) for their diphenylamine sulpho-acid.
The acids produced by me dissolve in concentrated sulphuric acid with very slight
brown coloration. Oxidizing agents, such as chloride of iron, chloride of potash, and
permanganate, color the solutions of the free acids a uniform dirty green.
The solutions assume the same color on standing in the air for a length of time.
The two above described monosulpho acids of diphenylamine are intended to be
formed into coloring matters, either separately or mixed by combination with diazo
and tetrazo compounds.
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. Process for the preparation of a mixture of sulpho acids of diphenylamine
containing mostly that sulpho acid whose soda salt is soluble in spirit by sulphonizing
diphenylamine with about the theoretically quantity of sulphuric acid of 66° at a
temperature of 140° to 160° Cent.
2. Process for the separation of the two mono sulpho acids referred to in the
preceding claim by making use of the unequal solubility of the soda salts in alcohol
or of the baryta lime and soda salts in water.
Dated this 11th day of September 1888.