DE1235324B - Process for the production of aminobenzolecarboxylic acids which can be used as color couplers - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

PATENT LETTERING

Int. CL:

C07c

German class: 12 q- 6/02

Number:

File number:

Registration date:

1,235,324
P29634IVb / 12q
June 16, 1962
March 2, 1967
September 14, 1967

Display day:

Issue date:

The patent specification corresponds to the patent specification

The present invention relates to a process for the production of useful as color couplers Aminobenzenecarboxylic acids.

From P. Glafkides, "Photographic Chemistry", Vol. 2, Fountain Press London, 1960, p. 609 are Color couplers known, for the production of which several stages are necessary. In contrast, that leads two-stage process according to the invention described below in a particularly simple and economical manner Way to compounds that are valuable as yellow color couplers and color images with improved Result in lightfastness.

The present invention relates to a process for the production of usable as color couplers Aminobenzenecarboxylic acids, which is characterized in that an aminobenzenecarboxylic acid alkyl ester the general formula

NH ₂ -COOR ₁ ,

in which R is a phenylene group, which can optionally be additionally substituted by one or more alkyl, alkoxy or carboxy groups, and R _{1 is} an alkyl group with 1 to 5 carbon atoms, with at least an equimolar amount of a malonic acid dialkyl ester whose alkyl radicals 1 to Containing 3 carbon atoms, condensed at a temperature between 150 and 190 ° C in the presence of a tertiary amine and optionally an additional solvent and the condensation product at a temperature of 60 to 80 ° C of a hydrolysis under alkaline conditions, preferably in an aqueous or alcoholic solution Alkali hydroxide, subject.

Although no restriction is made to any theoretical explanation, it can be assumed that in the condensation stage the malonic acid ester reacts with the aminocarboxylic acid alkyl ester with the escape of one molecule of alcohol and formation of an N-substituted malonic acid monoamide. During hydrolysis, this product first forms the free acid, of which two molecules _{react with one another with the loss of CO 2} and one molecule of malonic acid. In view of the strong reactivity of the malonic acid monoester, it is likely that further reactions will take place with the amino acid formed in the first condensation stage, resulting in an amino acid of higher molecular weight. It is therefore believed that the compounds of the invention have the formula

HOOC-R-NH-OC-CH ₂ -CO-Nh-R-COOH Process for the production of as a color coupler
usable aminobenzenecarboxylic acids

Patented for:

Pavelle Limited, Epsom, Surrey (Great Britain)

Representative:

Dr. F. Zumstein, Dr. E. Assmann

and Dr. R. Koenigsberger, patent attorneys,

Munich 2, Bräuhausstr. 4th

Named as inventor:

Gerald Noel White,

Carshalton, Surrey (UK)

Claimed priority:

Great Britain June 16, 1961 (21 906)

have, wherein R has the meaning given above.

Preferred alkyl aminobenzenecarboxylates are methyl or ethyl p-aminobenzoate, methyl or Ethyl m-aminobenzoate, methyl 3-amino isophthalate and ethyl 2-methoxy-4-aminobenzoate. Preferred dialkyl malonates are dimethyl malonate and Diethyl malonate. '

Examples of suitable tertiary amines which can be used as condensation catalysts are triethanolamine, Pyridine, dimethylaniline and collidine.

As already stated above, the condensation can optionally be carried out in the presence of a solvent be carried out, but the tertiary amine can also serve as a solvent.

The proportions of the alkyl aminobenzenecarboxylate and dialkyl malonate are not critical to condensation. It is generally the use of practically equimolecular Amounts preferred, but sometimes an excess of the diester is desirable.

The aminobenzenecarboxylic acids obtainable according to the invention can be used as such or in the presence an adsorbent to prevent diffusion, such as a long chain fatty acid, z. B. lauric or stearic acid, can be used as color couplers.

The products prepared according to the invention can generally be used as a free base in conjunction with

709 673/254

an absorbent as well as an azo coupler with the oxidation products of a developer instead of the azomethine couplers normally used for color images.

The following examples are intended to further illustrate the present invention.

example 1

264 g of ethyl p-aminobenzoate and 264 ml of diethyl malonate are quickly heated to 165 ° C with the addition of 20 ml of pyridine. It sets a violent development of ethanol and the temperature will hold itself without further heating. After you get the When the reaction has become more moderate, the mixture is held at 165 ° C until the loss occurs Ethanol becomes slow. The temperature is then increased to 175 to 180 ° C for half an hour. (Optionally, the temperature can be increased until the weight loss is close to a molar equivalent - based on the condensation product - ethanol plus the pyridine originally added provided that a temperature of 180 ° C is not exceeded.)

The product of the above procedure "is poured into 1 l of methanol while still hot with vigorous stirring. The faster this is done, the better the result, as a dense crystalline mass forms and whatever of the product is added thereafter becomes semi-solid and tends to form lumps put together. The mixture containing a thick crystalline mass is mixed with 1 l of water at 70.degree distributed to a uniform slurry and then stirred well while adding 200 ml of 50% aqueous Potassium hydroxide solution was added in small portions, whereby the pH value was adjusted before the next addition drops from 12 to about 10 and maintains the temperature at 70 ° C during the process. After With all of the caustic added, the solution is not held at 70 ° C longer than required to dissolve of the solid is necessary and a small sample does not precipitate when diluted with water results in more. The solution is then acidified to Congo red by adding 20% hydrochloric acid and filtered through cloth without cooling. The cake is dispersed in about 1 1 acetone and after at least Filtered off for 1 hour standing and washed with acetone. The yield is 180 g of pure white powder from F. = 262 ° C.

Example 2

2 kg of 3-aminoisophthalic acid dimethyl ester will be while warming in 1.3 l of dimethyl malonate with the addition of 200 ml of pyridine dissolved and then on a Maintained temperature between 160 and 175 ° C until evolution of methanol becomes slow. the Weight loss should be about 820 g after the end of the conversion. The remaining product that is roughly viscous and is discolored, while still hot while stirring vigorously to prevent clumping the precipitation of the dense crystals poured into 8 l of methanol. The resulting slurry is then diluted with 8 liters of water and processed into an even cream. The temperature is increased to 70 ° C while maintaining sufficient volume is stirred in by 50% sodium hydroxide solution in order to obtain a practically complete solution. It can a volume of about 2500 ml are required. Once you've got a clear solution, it becomes a test a small sample, and if it shows turbidity when diluted with water, the solution should be further Maintained at 70 ° C for 20 minutes. If a second sample becomes cloudy when diluted, is a further addition of 50% sodium hydroxide solution is necessary. If a sample of the solution becomes clear on dilution remains, the whole amount is acidified with hydrochloric acid (specific gravity 1.2) until the Congo red envelope is reached. The resulting precipitate is allowed to cool and then filtered. The cake is washed with water and dried. Yield 570g.

Claims (3)

Patent claims: 1. Process for the preparation of aminobenzenecarboxylic acids which can be used as color couplers. characterized in that an aminobenzenecarboxylic acid alkyl ester of the general formula NH ₂ R- -COOR ₁ , in which R is a phenylene group which can optionally be additionally substituted by one or more alkyl, alkoxyl or carboxyl groups, and R _{1 is} an alkyl group with 1 to 5 carbon atoms, with at least an equimolar amount of a malonic acid dialkyl ester whose alkyl radicals 1 to Containing 3 carbon atoms, condensed at a temperature between 150 and 190 ° C in the presence of a tertiary amine and optionally an additional solvent and the condensation product at a temperature of 60 to 80 ° C of a hydrolysis under alkaline conditions, preferably in an aqueous or alcoholic solution Alkali hydroxide, subject. 2. The method according to claim 1, characterized in that one is an aminobenzolecarboxylic acid alkyl ester and a dialkyl malonate condensed in practically equimolar amounts. 3. The method according to any one of the preceding claims, characterized in that a Excess of the tertiary amine is used as the solvent medium. 709 517/532 2.67 © Bundesdruckeroi Berlin