Improvements in the Manufacture of Phenyldimethylpyrazolone.
Year: 1890

page_text: Date of Application, 28th July, 1890
Complete Specification Left, 27th Apr., 1891-Accepted, 30th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Phenyldimethylpyrazolone.
We, Doctor LUDWIG SCHOLVIEN, of Grünau, near Berlin, Chemist and
LUDWIG FRIEDRICH RIEDEL, of 12/13, Gerichtsstrasse, Berlin, Merchant, both
in the Empire of Germany, do hereby declare the nature of this invention to be as
follows:-
This invention relates to the manufacture of phenyldimethylpyrazolone.
Hitherto, when manufacturing phenyldimethylpyrazolone, the combination of
phenylmethylpyrazolone had to be first produced by a special operation and then,
by another operation consisting of a treatment with methyliodine converted into
phenyldimethylpyrazolone.
By these improvements the phenyldimethylpyrazolone is produced in a single
operation, whereby the process is carried on with very little trouble, the yield is as
near as possible to the theoretical yield and the product itself is easily obtained in
a pure condition.
According to this invention phenylhydrazin, acetylacetic ether, and a methyl-
alkali sulphate such as methylsulphate of potassium or sodium, are caused to act
upon one another through the medium of a halogen in the form of a halogenalkali
salt, such as salts formed by the combination of iodine, bromine or chlorine with
sodium or potassium, or of a halogenhydric acid, such as iodhydric, bromhydric or
chlorhydric acid or of such salt in the presence of such acid.
The above ingredients are placed together with a suitable quantity of alcohol-
preferably ethyl or methyl alcohol in a digester in which they are submitted to a
temperature of about 160° to 185° C. for a period of about 10 to 12 hours
preferably under pressure after which the phenyldimethylpyrazolone can be
precipitated in the form of crystals and purified by the use of suitable chemical
agents.
BOLL
CT11000
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Phenyl-dimethyl-pyrazolone.
We, LUDWIG SCHOLVIEN, Doctor of Philosophy, of Grünau, and LUDWIG
FRIEDRICH RIEDEL, Manufacturing Chemist, of 12/13, Gerichtstrasse, Berlin,
both in the German Empire, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
5 ascertained in and by the following statement :-
This invention has for its object the casy manufacture of dimethyl-phenyl-
pyrazolone by a process consisting of a single operation, and yielding the product in
ately theorationl auantity

page_text: The chemical reactions which take place during this process are as follows:
The sodium methyl-sulphate acts on the sodium iodide (as may be concluded from
the abundance of sodium sulphate in the product of the reaction), thereby forming
sodium sulphate and methyl iodide, as indicated by the equation;
+
CH₂SO,Na NaI = Na₂SO, + CH¸I.
-
The methyliodide acts immediately upon the phenyl-hydrazin-aceto-acetic-ether
formed by the interaction of phenyl-hydrazin and aceto acetic ether (water being
split off), or rather upon the phenyl-methyl-pyrazolone produced from the latter
compound, (simultaneously with the separation of alcohol), thereby forming
hydriodide of dimethyl-phenyl-pyrazolone.
The small addition of hydriodic acid, mentioned above, serves to accelerate the
reaction, by promoting the interaction of the sodium methyl sulphate and iodide, as
has been proved by experiment. The methyl alcohol added to the mixture
serves as a diluent only.
In order to separate the free dimethyl-phenyl-pyrazolone, the brownish crystalline
product of the reaction is mixed with ether-alcohol, the solution thus obtained is
separated from the sodium sulphate which has remained undissolved, and the latter
is washed with ether-alcohol, after which the liquid is freed from ether and alcohol
by distillation.
The residue is dissolved in cold water, the solution is mixed with an excess of
soda-lye, to free the dimethyl-phenyl-pyrazolone which is then dissolved out by
shaking with chloroform. The chloroform solution is concentrated by evaporation,
petroleum-benzene is added to it, and thereby dimethyl-phenyl-pyrazolone separated
in the form of crystals, which are collected and purified by re-crystallization from
toluol, aceton, or alcohol.
The iodine used in the process may be quantitatively recovered from the residual
alkaline solution, as sodium iodide, by cautiously neutrallizing the said liquid with
sulphuric acid, evaporation, and subsequent re-crystallization.
In carrying out the above process, the proportions of reagents as given (supra)
are such as our experiments have shown to give the best results in regard to yield
and smoothness of working, but we do not limit ourselves thereto, nor to the
temperatures, or the duration of the heating above specified.
Furthermore, we may substitute for the methyl sulphate of soda, other methyl-
sulphates, such as methylsulphate of potassium, and instead of the sodium iodide,
we may take other haloid salts of the alkalis, such as sodium bromide or chloride,
and instead of hydriodic acid, we may take other halogen hydracids.
Also, instead of methyl-alcohol, we may employ ethyl-alcohol as the diluting
liquid.
The process may also be modified by omitting the sodium iodide and using
the other ingredients in the proportions as given below.
Phenyl-hydrazin
Accto-acetic ether
Methyl-sulphate of soda
-
-
-
100 parts by weight
125
150
"
دو

page_text: acetic ether (simultaneously with the liberation of water and alcohol), thereby
forming dimethyl-phenyl-pyrazolone, and hydriodic acid and giving off alcohol.
The hydriodic acid is therefore regenerated, and as it does not enter into combina-
tion with the dimethyl-phenyl-pyrazolone, it acts continuously repeatedly in the
manner described.
The latter, on the other hand, unites with the acid sodium sulphate formed
during the process, and produces a compound, which, at the temperature existing in
the digester, is split up into neutral sodium sulphate and a sulphate of dimethyl-
phenyl-pyrazolone, as indicated by the following equation;
GION WICH Une amethyl-pheny 1-pyrazolone, to US
manner described.
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The latter, on the other hand, unites with the acid sodium sulphate formed
during the process, and produces a compound, which, at the temperature existing in
the digester, is split up into neutral sodium sulphate and a sulphate of dimethyl-
phenyl-pyrazolone, as indicated by the following equation;
2 N₂OSO₂OHCH,N₂O = SO₂(ON₁), + SO₂(ОHCHN₂O)₂-
'11
This supposition is supported by the fact, that the product of the reaction contains
an abundance of neutral sodium sulphate, about one half of the quantity which is
formed by the process first described, that is to say, with the use of sodium iodide.
For separating the free dimethyl-phenyl-pyrazolone from the product of the
reaction, we proceed exactly as described above.
In this modification, the proportions of ingredients and the temperatures in the
digester may also vary, the methylsulphate of soda may be replaced by other
methylsulphates, the hydriodic acid by other halogen-hydracids, and the methyl-
alcohol serving as a diluent may be replaced by ethyl alcohol.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, we declare that what we
claim is;
1. The production of dimethyl-phenyl-pyrazolone, by heating phenyl-hydrazin,
aceto-acetic ether, the methyl sulphate of an alkali, a haloid salt of an alkali, such as
the chloride or bromide or iodide of sodium, a halogen hydracid, and methyl-alcohol
or ethyl-alcohol, at a suitable pressure, substantially as described.
2. The production of dimethyl-phenyl-pyrazolone, by heating phenyl-hydrazin,
aceto-acetic ether, the methyl sulphate of an alkali, a halogen hydracid and methyl-
alcohol or ethyl-alcohol, at a suitable pressure, substantially as described.
Dated this 25th day of Anril 1891.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicants.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicants.