Improvements in the Manufacture of Picric Acid.
Year: 1889

page_text: Date of Application, 15th Mar., 1889
Complete Specification Left, 11th Dec., 1889-Accepted, 1st Mar., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Picric Acid.
We ERNST EISENMANN Royal Assessor of Justice of Hotel Metropole London and
Dr. ALTO ARCHE Chemist of the Imperial Technical High School of Vienna of
Rennweg 18, Vienna do hereby declare the nature of our said invention to be as
follows --
Picric acid is at present manufactured by nitrating pure carbolic acid by means
of concentrated nitric acid under the influence of long continued high temperature.
The output of picric acid being about 120 per cent.
Our improvements consist in first transforming carbolic acid by the aid of
sulphuric acid into phenoltrisulphonic acid C. H, (H SO₂), OH afterwards con-
verting the phenoltrisulphonic acid with the aid of nitrate of soda into picric acid
and bisulphate of soda.
Under our improved process of manufacture the temperature need not exceed
100° Centigrade, the output of raw pieric acid being about 180 per cent. producing
after purification about 155 per cent. of pure pieric acid.
E. EISENMANN.
.DR. ALTO ARCHE,
Chemist of the Imperial Technical High School of Vienna.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Picric Acid.
We ERNST EISENMANN, Royal Assessor of Justice, of Hotel Metropole, London,
and Dr. ALTO ARCHE, Chemist of the Imperial Technical High School of Vienna,
of 18 Rennweg, Vienna, 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 :-
The object of our Invention is the process by which we are able to manufacture
picric acid without the use of concentrated nitric acid.
Heretofore, picric acid has been made by subjecting carbolic acid or phenol-
sulphonic acid to the action of highly concentrated nitric acid at a high temperature,
continued during a relatively long time.
Several inconveniencies accompany these processes. Highly concentrated nitric
acid acts, at a high temperature, not only with a nitrating, but also with an oxydizing
effect on the phenol, causing the output of picric acid to be diminished. The
nitrous gases which are developed during these processes are of the most undesirable
and unhealthy character.
By the present invention, we are able to reduce these inconveniencies and to
dispense with the use of free nitric acid by first transforming the phenol into
phenoltrisulphonic acid and then by the transformation of the latter into picric acid
and bisulphate of soda by means of nitrate of soda.
The transformation of carbolic acid into phenoltrisulphonic acid is done by its
being mixed with sulphuric acid, the said phenoltrisulphonic acid being advan-
tageously produced by heating, in leaden or lead-lined vessels, carbolic acid to
about 100-110° C. with pyrosulphuric acid.
The phenoltrisulphonic acid is then decomposed by adding it gradually to nitrate
of soda in proper proportion at a temperature of about 100° C.; the transformation
of the phenoltrisulphonic acid and nitrate of soda into picric acid and bisulphate of
soda goes on readily.

page_text: CH, OH + 3 H, SO. = C. H, (SO, H), OH + 3 H, O
C, H₂ (SO, H), OH + 3 Na NO, = C, H, (NO₂), OH + 3 Na H SO
Our invention avoids the use or formation of free nitric acid and thereby its
oxydizing action.
It also avoids high temperatures.
A greater output of picric acid is obtained than by the process commonly in use.
Having now particularly described and ascertained the nature of our said Inven
tion, and in what manner the same is to be performed, we declare that what we
claim is:
The improved process of manufacturing picric acid from carbolic acid, first by
transformation of the carbolic acid by means of sulphuric acid, preferably in the
state of pyrosulphuric acid, into phenoltrisulphonic acid, and then by transformation
of the phenoltrisulphonic acid by nitrate of soda into picric acid and bisulphate
of soda.
Dated this 5th day of Decembar 1880
ERNST EISENMANN.
DR. ALTO ARCHE.