Improvements in the Manufacture of Piperazine and its Salts.
Year: 1892

page_text: Date of Application, 7th 'Mar., 1892
Complete Specification Left, 7th Dec., 1892-Accepted, 4th Mar., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Piperazine and its Salts.
I BENJAMIN WILLCOX of 47 Lincoln's Inn Fields in the County of Middlesex
Patent Agent do hereby declare the nature of this invention (which has been
communicated to me from abroad by Farbenfabriken vormals Friedrich Bayer & Co.
of Elberfeld in the Empire of Germany) to be as follows:-
This invention relates to a new process for producing piperazine from the
dinitroso-derivatives of diphenylpiperazine, ditolylpiperazine dixylypiperazine and
dinaphthylpiperazine from the nitro-chloro-bromo- or iodine substitution products
of the said dialkylised piperazines or from the sulpho acids of the said substituted
piperazines.
My foreign correspondents have found that the above mentioned compounds viz.
the dinitrosoderivatives of diphenylpiperazine, ditolylpiperazine, dixylypiperazine
and dinaphtylpiperazine, the nitro-chloro-bromo- or iodine substitution products of
these dialkylised piperazines and likewise the sulpho acids of the aforesaid
substituted piperazines very readily yield the hydrochlorate of piperazine when
they are treated with salts of sulphurous acid and the products thus formed are
décomposed by hydrochloric acid.
The following may be given as an example for the conversion of dinitrosodiphenyl-
piperazine (first described in the Berichte der Deutschen Chemischen Gesellschaft
Volume XII. page 1795) into piperazine which process proceeds in general according
to the following equation
\SO,Na.
In this reaction an intermediate product is at first formed resulting from the
combination of the dinitrosodiphenylpiperazine with the salts of sodium bisulphite
and this compound is further decomposed by the addition of hydrochloric acid the
hydrochlorate of piperazine and amidophenoldisulphonate of sodium being
produced.
10 parts, by weight, of dinitrosodiphenyl piperazine are introduced into 43 parts,
by weight, of an aqueous solution of sodium bisulphite at 40° Beaumé and the
resulting mixture is heated to the boiling point. A violent reaction takes place
and without further heating the diuitroso compound perfectly dissolves with a
yellow colour the said addition product being formed. After adding 70 parts, by
weight, of concentrated muriatic acid and heating the whole liquid to the boiling
point the mono sodium salt of amidophenoldisulpho acid partly separates in small
prismatic crystals besides sodium chloride it remains partly in solution together
with the hydrochlorate of piperazine formed in the reaction." After removing the
precipitate the liquid is rendered alkaline by adding soda-lye and the piperazine is
distilled over in steam. The distillate is neutralized with hydrochloric acid and,
thereupon, evaporated. By decomposing with alkalies the hydrochlorate of
piperazine thus formed and distilling the free piperazine is obtained in a pure
state.
This reaction proceed extremely well and yields better results than those
obtained by the method hitherto employed.

page_text: In an analogous manner the before mentioned nitro-chloro-bromo- and iodine
substitution products of diphenylpiperazine, ditolylpiperazine dixylylpiperazine and
dinaphthylpiperazine and the sulpho acids of all these substituted piperazines can
be employed for the production of piperazine.
Dated this 7th day of March 1909
J. H. JOHNSON & Co.,
47, Lincoln's Inn Field's, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Piperazine and its Salts.
I BENJAMIN WILLCOX of 47 Lincoln's Inn Fields, in the County of Middlesex
Patent Agent, do hereby declare the nature of this invention (which has
been communicated to me from abroad by Farbenfabriken vorm. Friedrich
Bayer & Co. of Elberfeld, 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 a new process for producing piperazine from dinitroso-
diphenyl piperazine.
My foreign correspondents have found that when the dinitrosoderivate of diphenyl-
piperazine is. treated with sulphurous acid or its salts, it very readily yields
piperazine.
The following may be given as an example of the mode of converting dinitroso-
diphenylpiperazine (first described in the Berichte der Deutschen Chemischen
Gesellschaft Volume XII. page 1795) into piperazine by means of sodium bisulphite,
the change taking place in accordance with the following equation:
NO CHN
NCH - NO + 6 NaHSO₁ =
CIL
CIT
10 parts by weight of dinitrosodiphenylpiperazine or the corresponding quantity
of a wet paste thereof (containing for example 15 per cent. of the dinitroso
compound) are introduced into 75 parts by weight of an aqueous solution of sodium
bisulphite (containing 40 per cent. of NaHSO,) and the resulting mixture is heated
to the boiling point. A violent action takes place the dinitroso compound dis-
.solving entirely without further heating being necessary forming a yellow coloured
liquid.
After adding 50 parts by weight of concentrated muriatic acid (or 20 parts by
weight of concentrated sulphuric acid at 66 degrees Baumé) and heating to the
boiling point for some time, a part of the amidophenoldisulpho acid separates
in small prismatic crystals together with sodium chloride a part remaining in
solution together with the hydrochloride of piperazine which is formed in the
reaction. The liquid is rendered alkaline either after the precipitate has been
filtered off or directly by adding soda lye and the piperazine is distilled over in
steam. The distillate is neutralised with muriatic acid and then evaporated. By
decomposing with alkalies the hydrochloride of piperazine thus formed and subse-
quently distilling, the free piperazine is obtained in a pure state.
If in place of sodium bisulphite or other alkaline salts of sulphurous acid free

page_text: SECOND EXAMPLE.
Into a mixture of 10 parts by weight of dinitrosodiphenylpiperazine or the
corresponding quantity of a wet paste thereof (containing for instance 15 per cent.
of pure dinitroso compound) and 30 parts by weight of cold water a current of
sulphurous acid is passed until the suspended dinitroso compound has dissolved
forming a yellow liquid. To obtain piperazine this solution is treated in the
manner described in the previous example i after or without adding for
instance 25 parts by weight of muriatic acid (20 degrees Baune) or 10 parts by
weight of concentrated sulphuric acid (66 degrees Baume) the liquid is heated to
the boiling point for some time and the liquid is rendered alkaline either directly
or after the precipitate has been filtered off by adding soda lye or the like, and the
piperazine is distilled over in steam. The conversion of the raw product into
pure piperazine is effected in the manner described in the above first example.
These reactions proceed extremely well and yield better results than are obtained
by the method hitherto employed.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:-
1. The process for producing the sulphurous salt of piperazine by treating
dinitrosodiphenylpiperazine (first described in the Berichte der Deutschen
Chemischen Gesellschaft Volume XII. page 1795) with sulphurous acid or salts
thereof.
2. The process for producing piperazine by treating dinitrosodiphenylpiperazine
with sulphurous acid or salts thereof, heating the liquids thus obtained to the
boiling point either with or without the previous addition of a mineral acid,
filtering off the precipitate or directly rendering the resulting liquid mixture
alkaline, distilling and condensing the piperazine which distils over, and subse-
quently converting the raw product thus obtained into pure piperazine by means of
the methods employed in chemistry for such or analogous purposes.
3. The process for producing salts of piperazine by treating dinitrosodiphenyl-
piperazine with sulphurous acid or salts thereof heating the liquids thus obtained to
the boiling point with or without the previous addition of a mineral acid filtering
off the precipitate or directly rendering the resulting liquid mixture alkaline,
distilling and condensing the piperazine which distils over either in a receiver con-
taining a mineral acid or subsequently adding to the distillate a mineral acid and
evaporating the solutions of salts of piperazine thus formed.
4. In the manufacture or production of piperazine the treatment of dinitroso-
diphenylpiperazine with sulphurous acid or salts thereof.
Dated this 7th day of December 1892.
B. WILLCOX.