DE1258411B - Process for the preparation of benzanthronyl-pyrazole-anthrones - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C07d

German class: 12 ρ - 8/01

Number: 1258 411

File number: F 36553IV d / 12 ρ

Filing date: April 14, 1962

Open date: January 11, 1968

It is known that N (l) - [Bz-l'-benzanthronyl] pyrazolanthrones by condensation of pyrazole anthrones with Bz-1-halobenzanthrones in high-boiling organic solvents, such as nitrobenzene, in the presence of acid-binding agents can produce (German patents 468 896, 490 723 and 520 395). The products thus obtained often only have an unsatisfactory degree of purity. Much purer products are obtained in mostly higher yields by condensation of Bz-1-chlorobenzanthrones with the potassium salt of pyrazole anthrones in Dialkylformamides (German Patent 1 000 383). In addition, one arrives at benzanthronylpyrazole anthrones, when Bz-1-nitrobenzanthrone with pyrazole anthrones in the presence of potassium carbonate in organic solvents is condensed at higher temperatures (German patent specification 500 520).

It has now been found that N (I) - [Bz-I '-Benzanthronyl] -pyrazolanthrones in excellent purity and yield by condensation of Bz-1-nitro-ao benzanthrone with pyrazole anthrones in the presence of potassium carbonate in high-boiling solvents elevated temperatures obtained by having the condensation at temperatures between 120 and 155 ° C in dimethylformamide.

This result is surprising since the conversion of pyrazole anthrones to the N (I) - [Bz-I'-benzanthronyl] pyrazole anthrones by the process of German patent specification 1 000 383 is only possible within narrow limits, which can be seen from the fact that the Bz-1-bromobenzanthrones react only poorly or not at all, although bromine derivatives are generally particularly suitable for anthrimide condensation. Even if a Bz-1-chlorobenzanthrone, for example a Bz-1-chloro-Bz-2-alkylbenzanthrone, is reacted in dimethylformamide with the potassium salt of pyrazole anthrone according to this process, a strong reducing effect of the dimethylformamide is already noticeable here leads to the dehalogenation of part of the Bz-1-chlorobenzanthrone used. The consequence of this is a strong reduction in the yield of N (1) - [Bz-1 '- (Bz-2'-alkyl) -benzanthronyl] -pyrazolanthrone. This influence of the reducing action of dimethylformamide, which has a very detrimental effect on the known process, can be avoided either by adding a suitable oxidizing agent, for example nitrobenzene or potassium 3-nitrobenzenesulfonate, or by passing a brisk stream of molecular oxygen over the reaction mixture. As can be seen in this connection from Table I, the results of a series of tests for the production of
Benzanthronyl-Pyrazole-Anthrones

Applicant:

Farbwerke Hoechst Aktiengesellschaft
formerly Master Lucius & Brüning,
6230 Frankfurt-Höchst

Named as inventor:
Dipl.-Chem. Dr. Ernst Spietschka,
6271 Oberauroff

reproduces, can be in the implementation of Bz-1-chloro-Bz - 2 - isopropylbenzanthrone with pyrazole anthrone (K-Salz) in dimethylformamide in the presence of such oxidizing agents a considerable improvement in the yield of N (I) - [Bz-I '- (Bz-2'-isopropyl) -benzanthronyl] -pyrazolanthrone than if the same reaction is carried out in the absence of an oxidizing agent:

Table I.

Oxidizing agent the end
prey Enamel
Point
⁰ C 3-nitrobenzenesulfonic acid
potassium 68.5
83.5
81.5
89 362
359 to 361
362 to 363
362 to 364 Nitrobenzene
Airflow

In view of the above test results relating to the condensation of pyrazole anthrone potassium with a Bz-1-chlorobenzanthrone in dimethylformamide would have in the analogous implementation with Bz-1-nitrobenzanthrone actually have to be expected that part of the nitro compound used will be lost, assuming that this is the nitrobenzanthrone starting product itself can be effective as an oxidizing agent and therefore no longer for the actual condensation is available. As a result, poor yields had to be expected. Table II becomes clearly that such behavior of dimethylformamide in the context of the condensation according to the invention does not actually apply:

709 718/427

Table Π yield
% Melting point
⁰ C Reaction partner 94 394 to 400 Bz-1-nitrobenzanthrone -j- pyrazolanthrone (K-SaIz) 95 398 to 400 the same ·; - ~ 92.5 412 to 415 Bz-1-nitrobenzanthrone + 8-chlorpyrazolanthrone (K-SaIz) 95 419 to 421 the same traces black component Bz-1-nitrobenzanthrone + 8-ethoxypyrazole anthrone (K-SaIz) 85 380 to 382 the same solvent Nitrobenzene Dimethylformamide Nitrobenzene Dimethylformamide Nitrobenzene Dimethylformamide

Table II also provides information that the degree of conversion in the condensation of Bz-1-nitrobenzanthrone with the 8-Äthoxypyrazolanthron in ao nitrobenzene according to the method of the German Patent specification 500 520 is far less than that when the same reaction in dimethylformamide after the claimed method is carried out.

Taking into account the results obtained when carrying out the condensation of pyrazole anthrones are obtained with benzanthrones by conventional processes, it was therefore not foreseeable that a nitro compound of benzanthrone would react in the manner indicated. It runs the process according to the implementation so smooth that you can rely on the separate representation of the potassium salt Pyrazolanthrones and the removal of the resulting water of reaction according to the patent 1000 383 can do without, which represents a significant simplification. Another advantage of the inven-. The process according to the invention can be seen in the fact that it is derived from a technically easily accessible benzanthrone derivative goes out. The Bz-1-chlorobenzanthrone is known to be difficult to access in pure form, while the Bz-1-nitrobenzanthrone in excellent purity and yield in the nitration of benzanthrone in halogenated or nitrated aliphatic hydrocarbons, such as. B. ethylene chloride or Nitromethane.

The compounds obtained according to the invention are intermediates for the production of more valuable products Vat dyes.

For example

22 parts by weight of pyrazolanthrone, 27.5 parts by weight of Bz-1-nitrobenzanthrone, 14 parts by weight of anhydrous potassium carbonate and 250 parts by weight of dimethylformamide are refluxed for 2 to 3 hours. After cooling, the reaction product is filtered off with suction, washed with dimethylformamide and then with water until neutral. The yield of dry N (l) - [Bz-l'-Benzanthronyl] -pyrazolanthron is about 95%> of the melting point of the yellow crystalline compound at 398-400 ⁰ C.

Example 2

If, in Example 1, the pyrazole anthrone is replaced by 25.4 parts by weight of 8-chloropyrazole anthrone and the procedure described there, the N (l) - [Bz-l'-benzanthronyl] -8-chloropyrazole anthrone in is obtained in a yield of over 95% Form of yellow crystals with a melting point of 419 to 421 ⁰ C.

Example 3

If, in Example 1, the pyrazole anthrone is replaced by 26.4 parts by weight of 8-ethoxypyrazole anthrone, this is obtained after the reaction has ended, the N (l) - [Bz-l'-benzanthronyl] -8-ethoxypyrazolanthrone is obtained in a yield of about 85%. The compound forms orange crystals that melt at 380 to 382 ° C.

Claims (1)

Claim: Process for the production of. Benzanthronylpyrazole anthrones by condensation of Bz-1-nitrobenzanthrone with pyrazole anthrones in the presence of potassium carbonate in high-boiling solvents at elevated temperatures, characterized in that the condensation is carried out at temperatures between 120 and 155 ^° C. in dimethylformamide. Considered publications:
German patent specifications No. 500 520, 1000 383. 709 718/427 12.67 ® Bundesdruckerei Berlin