DE1144285B - Process for the preparation of 2, 5-diarylaminoterephthalic acids - Google Patents

Description

GERMAN

PATENT OFFICE

C23672IVb / 12q

REGISTRATION DATE: MARCH 17, 1961

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: FEBRUARY 28, 1963

For the production of quinacridones, which are of technical importance as valuable pigment dyes are 2,5-diarylamino-terephthalic acids the general formula

COOH

Aryl · HN ·

NH · aryl

COOH

the immediate preliminary products. According to Liebermann (»Liebigs Annalen«, vol. 404 [1914], P. 272) obtained by oxidation of 2,5-diarylamino-3,6-dihydro-terephthalic acid dialkyl esters the general formula

COO · alkyl

Aryl · HN

NH · aryl

COO · alkyl

with iodine in an alcoholic solution or with oxygen in the air in glacial acetic alcohol and by saponification of the 2,5-diarylamino-terephthalic acid dialkyl ester thus obtained and isolated with alcoholic lye. However, this method has not found its way into practice, since the work is inconvenient with iodine or with a mixture of glacial acetic acid and alcohol.

A simplification brought the method described in Belgian patent 579 621, according to which 2,5-diarylamino-3,6-dihydro-terephthalic acid dialkyl ester in aqueous-alcoholic liquor with a Oxidizing agents with simultaneous oxidation and saponification in a single reaction stage 2,5-diarylaminoterephthalic acids result. As an oxidizing agent is used here m-nitrobenzenesulfonic acid sodium, of which at least 1 mole per Mol of the 2,5-diarylamino-3,6-dihydroterephthalic acid ester used is required. According to the information the aforementioned Belgian patent can be used instead of sodium m-nitrobenzenesulfonate also use atmospheric oxygen as an oxidizing agent, but then the process is' much less effective and significantly more difficult to control "(see Belgian patent specification 579 621, p. 7, para. 2, Lines 8 to 11).

Process for the production of
2,5-diarylaminoterephthalic acids

Applicant:

Cassella Farbwerke Mainkur

Corporation,
Frankfurt / M.-Fechenheim

Dr. Heinrich Ritter, Dörnigheim (Kr.Hanau),

and Dr. Erwin Herrmann, Frankfurt / M.,

have been named as inventors

It has now been found that 2,5-diarylamino-3,6-dihydro-terephthalic acid esters in aqueous-alcoholic solution even when using atmospheric oxygen without the difficulties mentioned can be converted directly into the 2,5-diarylamino-terephthalic acids if the reaction mixture small amounts of a quinone sulfonic acid, such as naphthoquinone, anthraquinone, and phenanthrenequinone sulfonic acid, clogs as an oxygen carrier.

As a further simplification of the present process, it has been found that it is not necessary to the 2,5-diarylamino-3,6-dihydro-terephthalic acid esters used as starting materials to use as isolated and purified substances; one can rather see them directly in the form of their educational mixtures, as in the reaction of 1 mole of succinylosuccinic acid ester with 2 moles of an arylamine obtained in alcoholic solution, use.

example 1

In 115 parts of methanol, 30 parts of 2,5-dianilino - 3,6 - dihydro - terephthalic acid - diethyl ester, 93 parts of 14% sodium hydroxide solution and 1.5 parts of anthraquinone-2-sulfonic acid registered. The mixture is then refluxed for about 3 hours with the introduction of air, during which time solution occurs. Then be about 90 parts of methanol are distilled off. Further work-up can be carried out using two methods: a) The remaining reaction solution becomes Congo acidic with about 66 parts of 25% sulfuric acid placed, the precipitated product is filtered off, washed neutral with water and dried.

309 537/403

This gives 24 parts (= 93% of theory) 2,5-dianilino-terephthalic acid with a melting point of 330 ° C. in the form of a violet, crystalline powder, b) After cooling and standing for several hours, the yellow, crystalline disodium salt which has precipitated from the reaction solution is filtered off with suction , washed with saturated sodium chloride solution, dissolved in about 500 parts of hot water and acidified with about 14 parts of concentrated hydrochloric acid. Then, it is suctioned off, washed neutral with water and dried to obtain 23.8 parts (= 92.5% of theory) of 2,5 - dianilino - terephthalic acid of melting point 330 receives ⁰ C.

Example 2

In 152 parts of n-butanol, 29.9 parts of 2,5-di- (p - toluidino) - 3,6 - dihydro - terephthalic acid - dimethyl ester, 114 parts of 22% sodium hydroxide solution and 1.5 parts of anthraquinone l, 5- disulfonic acid entered. ^{The mixture is then heated to 80 to 90 °} C. for 4 to 5 hours with the introduction of air, during which time solution occurs. About 230 parts of an azeotropic mixture (butanol-water) with a boiling point of 92 ° C. are then distilled off, a total of about 220 parts of water being allowed to run in at the same time during the course of the distillation. As in Example 1, further work-up can be carried out by two methods. In any case, 25.4 parts (= 92% of theory) of 2,5-di- (p-toluidino) terephthalic acid of melting point 334 ⁰ C in the form of a purple, crystalline powder.

Example 3

Is used in Example 2 instead of 2,5-di- (p - toluidino) - 3,6 - dihydro - terephthalic acid - dimethyl ester 35 parts of 2,5-di- (o-chloroanilino) -3,6-dihydroterephthalic acid diethyl ester and works otherwise as indicated there, then 29 parts (= 94% of theory) of 2,5-di- (o-chloroanilino) -terephthalic acid are obtained with a melting point of 342 ° C in the form of a purple powder.

Example 4

25 parts of diethyl succinylosuccinate and 26 parts of p-chloroaniline are introduced into 195 parts of n-butanol. Then one introduces 0.6 parts of hydrogen chloride and heated for 1 hour at 90 to 100 ⁰ C, whereby the 2,5-di (p-chloroanilino) -3,6-dihydro-terephthalic acid diethyl ester is produced. 145 parts of 22% strength sodium hydroxide solution and parts of anthraquinone-1-sulfonic acid are then introduced into the reaction solution. The mixture is then heated ^{to 80 to 90 °} C. for up to 5 hours with the introduction of air. The further reaction and work-up are carried out as in Example 2, 35 parts (= 86% of theory) of 2,5-di- (p-chloroanilino) -terephthalic acid having a melting point of 332 ° C. being obtained in the form of a red, crystalline powder.

Claims (2)

PATENT CLAIMS: 1. Process for the preparation of 2,5-diarylamino - terephthalic acids from 2,5 - diarylamino-3,6 - dihydro - terephthalic acid - dialkyl esters by the simultaneous action of aqueous-alcoholic alkalis and atmospheric oxygen at elevated temperature, characterized in that the reaction mixture is added adding small amounts of quinone sulfonic acids, such as naphthol high quinone, anthraquinone and phenanthrenequinone sulfonic acids, as oxygen carriers. 2. The method according to claim 1, characterized in that the starting materials serving 2,5-diarylamino-3,6-dihydro-terephthalic acid dialkyl ester in the form of their formation mixtures, as they are in the implementation of 1 mol Succinylosuccinic acid ester with 2 mol of an arylamine available in alcoholic solution are used. © 30J 537/403 2.63