CH125474A - Process for the preparation of methylpyrazolanthrone. - Google Patents
Process for the preparation of methylpyrazolanthrone.Info
- Publication number
- CH125474A CH125474A CH125474DA CH125474A CH 125474 A CH125474 A CH 125474A CH 125474D A CH125474D A CH 125474DA CH 125474 A CH125474 A CH 125474A
- Authority
- CH
- Switzerland
- Prior art keywords
- preparation
- anthrone
- methylpyrazolanthrone
- pyrazole
- starting material
- Prior art date
Links
Landscapes
- Nitrogen Condensed Heterocyclic Rings (AREA)
Description
Verfahren mir Darstellung von llletliylhyrazolantliroll. Es wurde gefunden, dass man Methyl- pyrazolanthron in vorteilhafter - Weise ge winnen kann, wenn man Pyrazolanthron mit methylierenden Mitteln in Anwesenheit von sauren Kondensationsmitteln behandelt. Man kann hierbei zum Beispiel vorteilhaft in der Weise verfahren, dass' man Pyrazolanthron, sei. es mit Schwefelsäuremethylestern, sei es mit einem geeigneten Gemisch von reinem Methylalkohol und Schwefelsäure, auf höhere Temperaturen erhitzt.
Beispiel: In 120 Gewichtsteile konzentrierte Schwe felsäure lässt man bei Temperaturen unter 40' langsam unter gutem Rühren und Küh len 32 Gewichtsteile Methylalkohol einlaufen, l:rä :;t dann in die Mischung 20 Gewichtsteile Pyrazola.nthron ein, erhitzt langsam auf 170 und hält etwa drei Stunden bei der g r <B>1</B> eiehen Temperatur. Das Ende der Reaktion ist daran zu erkennen,
dass eine herausgenom mene Probe der Schmelze beim Verdünnen mit Wasser einen Niederschlag gibt, der sich in wässerigen Alkalihydroxydlösungen nicht mehr löst. Man giesst sodann in Wasser, saugt ab, trennt erforderlichenfalls durch Erwärmen mit verdünntem Alkalihydroxyd von etwa unverändertem Ausgangsmaterial ab und trocknet. Zur völligen Reinigung kann das Produkt aus Monochlorbenzol um kristallisiert werden. Man erhält Mono- methylpyrazolanthron in gelben Nadeln, die bei 221 bis 224' schmelzen.
Das neue Methylpyrazolanthron ist ein wertvolles Ausgangsmaterial zur Darstellung von Farbstoffen.
Procedure with representation of llletliylhyrazolantliroll. It has been found that methyl pyrazole anthrone can advantageously be obtained if pyrazole anthrone is treated with methylating agents in the presence of acidic condensing agents. One can, for example, advantageously proceed in such a way that one is pyrazolanthrone. it is heated to higher temperatures with sulfuric acid methyl esters, be it with a suitable mixture of pure methyl alcohol and sulfuric acid.
Example: 32 parts by weight of methyl alcohol are slowly run into 120 parts by weight of concentrated sulfuric acid at temperatures below 40 'with thorough stirring and cooling, then 20 parts by weight of pyrazole thrones are added to the mixture, heated slowly to 170 and held about three hours at the highest temperature. The end of the reaction can be recognized by
that a sample of the melt taken out, when diluted with water, gives a precipitate which no longer dissolves in aqueous alkali hydroxide solutions. It is then poured into water, filtered off with suction, if necessary separated from roughly unchanged starting material by heating with dilute alkali metal hydroxide and dried. The product can be crystallized from monochlorobenzene for complete purification. Monomethylpyrazolanthrone is obtained in yellow needles which melt at 221 to 224 '.
The new methylpyrazolanthrone is a valuable starting material for the preparation of dyes.
Claims (1)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE125474X | 1926-01-13 |
Publications (1)
Publication Number | Publication Date |
---|---|
CH125474A true CH125474A (en) | 1928-04-16 |
Family
ID=5658683
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CH125474D CH125474A (en) | 1926-01-13 | 1927-01-11 | Process for the preparation of methylpyrazolanthrone. |
Country Status (1)
Country | Link |
---|---|
CH (1) | CH125474A (en) |
-
1927
- 1927-01-11 CH CH125474D patent/CH125474A/en unknown
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