CS208620B1 - Process for preparing disazo dyes - Google Patents

Abstract

Method for preparing disazo dyes of the general formula COCH, COCH, I 3 I 3 HOOC - B - N = N - CHCONH - A - NHCOCH - N = N - B - COOH where B is phenylene optionally substituted by halogen, alkyl, alkoxy, trifluoromethyl, carbalkoxy, or nitro and A is an arylene residue optionally further substituted by one or two halogen atoms, alkyl, alkoxy, trifluoromethyl, or cyano.

Description

(54) A method for preparing disazo dyes

A process for preparing disazo dyes of the general formula

COCH, COCH,

I ³ I ³

HOOC - B - N = N - CHCONH - A - NHCOCH - N = N - B - COOH wherein B is phenylene optionally substituted with halogen, alkyl, alkoxy, trifluoromethyl, carbalkoxy, or nitro and A is an arylene residue optionally further substituted with one or two halogen atoms, alkyl, alkoxy, trifluoromethyl or cyano.

208 620

208 620

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of disazo dyes having two carboxyl groups per molecule, comprising the coupling of diazotized aminocarboxylic acids with bisacetoacetyl aromatic diamines in a molar ratio of 2: 1.

COCH. COCH.

I ³ I ³

HOOC - Β -N = N-CHCONH-A -NHCOCH -N = N-B-COOH (I) wherein A and B are arylene residues, both of which are optionally longer substituted by groups having no solubilizing character.

These disazo dyes are in themselves insoluble colored substances of yellow to orange shades, however, they find their main use as intermediates for the preparation of highly stable organic so-called azocondensation pigments. The high demands placed on this type of pigment are also transferred to the quality requirements of the above disazo dyes. In this respect, high demands are placed in particular on the content of by-products in the disazo dyes, and this is already the product of the imperfect coupling of the general formula (II),

COCH.

I ³

HOOC-B-N = N-CHCONH-A-NHCOCH ₂ COCH ₃ (II) passive component residues, decomposition products of the active component or inorganic salts. Due to its low solubility and further to the adsorption capacity of the large surface area of the disazo dye, the organic substances are partly transferred to the pigment produced from the disazo dye. Here they either adversely affect the brilliance of its shade, to which the yellow pigments are particularly sensitive, or even the stability in solvents or migration. The attempt to ensure that the coupling reaction for the preparation of disazo dyes is as selective as possible is further motivated by increasing the yield of the reaction. A suitable process for the preparation of said disazo dyes is not described in the literature.

Several variants of the process of coupling a diazotized aminocarboxylic acid with a passive component have now been found which make it possible to prepare disazo dyes of the formula I in satisfactory quality.

The coupling can be carried out over a relatively wide pH range of 3.5 to 13, and the procedures differ mainly in the pH value of the coupling.

The passive component can be used for coupling either as a solution of its enolform or as a fine precipitate of a ketoform precipitated from an alkaline solution by acidification. This gives the basic possibilities of the coupling reaction.

Coupling in an alkaline medium usually at pH values of 7.5 to 12.5 proceeds very rapidly even at normal temperature and the disazo dye formed is partially dissolved in the form of the disodium salt. The desired pH can be maintained by the continuous addition of an alkali metal hydroxide solution or by buffering an acidic solution of the diazotized aminocarboxylic acid. The physical form in which the disazo dye is formed is not suitable for isolation and it is expedient to acidify the reaction suspension after the coupling to pH 2 to 3 sec to isolate the disazo dye as the free carboxylic acid or vice versa by adding an inorganic sodium salt such as sodium chloride or sodium sulfate. , convert any disazo dye at a pH of about 12 to the carboxylic acid disodium salt, which can then be easily isolated by filtration.

The second and second way of carrying out the reaction is by coupling at a pH of less than 7, where the passive component exists predominantly in the form of its less soluble ketoform and is excreted as a fine precipitate from solution. The desired pH is maintained either by adding a buffer (e.g., a mixture of sodium acetate and acetic acid) added to the passive component or diaza solution, or by continuously adding alkali metal hydroxide solutions to the coupling suspension. In the acidic pH range, the coupling rate is lower than in the alkaline region, but it can be accelerated by increasing the temperature up to 80 ° C and at the same time ensuring a virtually 100% conversion of the passive component to the desired disazo dye. Another possibility is to assist the coupling by the addition of auxiliaries such as, for example, dispersants, for example, alkylarylsulfonates or polycondensation products of ethylene oxide.

At the end of the coupling, the disazo dye exists partly in the sodium salt form and partly as the free acid. The sodium salt content is mainly dependent on the pH at which the coupling was terminated, and if the free acid-only disazo dye is not required for further purposes, a mixture of both free acid and sodium salt can be isolated.

A combination of the above two processes is a coupling beginning in the alkaline region and ending in the acidic pH range. In this process, it is not necessary to increase the temperature or to add other auxiliaries to achieve a sufficient reaction rate. The desired pH in the second part of the coupling can be maintained again by buffering or by the addition of alkaline.

Another method of performing the coupling is by adding an alkaline solution of the passive component to a diaza solution, the pH of which is adjusted with a buffer to a slightly acidic reaction. The stability of the diazonium salts of aminocarboxylic acids allows this process even at temperatures of 20 ° C, when the coupling proceeds very rapidly.

Finally, coupling may also be accomplished by adding the passive component solution and the diazotized aminocarboxylic acid solution simultaneously at a molar ratio of 1: 2 to a buffer solution or to water only while adding alkali to maintain the desired pH range.

Of the aminocarboxylic acids of formula III

HOOG-A-NHg (III) wherein A is an orylene radical, in view of the further use of the disazo dyes, aminocarboxylic acids of the general formula IV are particularly suitable

COOH wherein Z represents a hydrogen or halogen atom, an alkyl, alkoxy, trifluoromethyl, carbalkoxy or nitro group and η = 1 or 2. Suitable components of formula IV are, for example:

. 3-aminobenzoic acid

3-amino-4-chlorobenzoic acid

3-amino-4-methylbenzoic acid

3-amino-4-methoxybenzoic acid

3-amino-6-chlorobenzoic acid

Ί— ογγΊγίλ-Α-r r ob ob »1 of the other then

208 620

3-Amino-4-carbomethoxybenzo 2-amino-chlorobenzo 2-amino-5-chlorobenzo

4-amino-benzoic acid

4-amino-3-nitrobenzoic acid

Among the passive components of formula V ch ₃ coch ₂ cohn-b-nhgoch ₂ coch ₃ (V), the bisacetoacetyl diamines of formula IV have proved to be the most suitable,

wherein X ₁ and X _{2 are} hydrogen, halogen, alkyl, alkoxy, trifluoromethyl or cyano. Bisacetoacetylated 3-amines of formula (V) or (VI) are prepared by treating an aromatic diamine substituted with the above groups by treating ethyl acetate or diketene. These are, for example, the following diamines:

1,4-diaminobenzene

1,4-diamino-2-chlorobenzene

1,4-diamino-2-methylbenzene

1,4-diamino-2-methoxybenzene

1,4-diamino-2-cyanobenzene

1,4-diamino-2,5-dichlorobenzene

1,4-diamino-2,5-dimethylbenzene

1,4-amino-2-chloro-5-methylbenzene

1,4-diamino-2-methoxy-5-methylbenzene

1.3- d ia minoenzene

1,3-diamino-4-chlorobenzene

1,3-3-amino-4,6-dichlorobenzene

1.5- diaminonaftalen

2.6- diaminonaftalen

The disazo dyes obtained by the process according to the invention are further processed either in the form of aqueous pastes or, after drying and milling, as powder products.

The following examples serve to illustrate the process of the invention in more detail.

Example 1

35.4 g of 3-amino-4-chlorobenzoic acid are dissolved in 500 ml of water by addition of 8.24 g of sodium hydroxide, 14.45 g of sodium nitrite are added and this solution is slowly poured into a dilute solution of 26.3 g with good stirring. hydrochloric acid. After blunting excess leaven4

208 820 nitrous nitride or amidosulfonic acid was sclerified with diatomaceous earth and gradually added to a suspension of 30.4 g of 1,4-bisacetoacetylamino-2,5-dimethylbenzene in water heated to 60 ° C. This suspension is prepared beforehand by acidifying an aqueous alkaline solution of the enolform of said passive component with acetic acid to pH = 5.2.

By continuously adding the dilute sodium hydroxide solution, the pH of the coupling mixture is maintained between 4 and 6.5. After coupling, the reaction slurry is heated to 95 ° C, filtered and washed with hot water until the filtrate to chloride reaction is lost. 330 g of an aqueous paste are obtained containing 65.6 g of a yellow-orange disazo dye.

Example 2

270 g of an aqueous paste containing 40.7 g of 3-amino-4-carbomethoxybenzoic acid are stirred in 200 ml of water, 185 ml of 10% hydrochloric acid are added and the solution is sodiumised by adding sodium nitrite solution. The cloudy diaza solution is sclerified with diatomaceous earth and added, initially quickly, then slowly, to a solution containing: 34.5 g of 1,4-bisacetoacetylamino-2,5-dichlorobenzene, 900 ml of water, 8 g of sodium hydroxide and 49 g of sodium acetate. The coupling takes about 1 hour at 25-30 ° C. After coupling, the slurry is heated to 95 ° C, filtered, the filter cake containing 73.5 g of yellow disazo dye is stirred in 1100 ml of water, acidified by addition of hydrochloric acid to pH = 2.5. reaction of the filtrates to chloride ions, dried at 80 ° C and ground. Example 3

35.2 g of 3-amino-4-methoxybenzoic acid are diazotized at 20 DEG C. in a manner similar to Example 1, the diazo compound solution is sclerified with the addition of carboraffin and the pH of the clear sintered diaza solution is adjusted to 4.3 with 49 g of sodium acetate.

To this solution was added an alkaline solution of 32.5 g of 1,4-bisacetoacetylamino-2-chloro-5-methylbenzene in 400 ml of water over 5 minutes. Coupling after 1.5 hours is complete and the resulting disazo dye is filtered off, washed and dried. 67.4 g of dry product are obtained.

Example 4

The solution prepared by dissolving 29.0 g of 1,4-bisacetoacetylamino-2-methylbenzene in 900 ml of water with the addition of 8 g of sodium hydroxide, together with the acidic solution prepared by diazotization, 36.8 g of 3-nitro-4-aminobenzoic acid is added simultaneously to dilute sodium acetate solution. Both solutions are metered in such a way that the molar ratio of diaza to passive component of 2: 1 is maintained continuously. Coupling yields 67.5 g of a yellow-orange disazo dye.

Example 5

34.3 g of 3-amino-4-chlorobenzoic acid are thiolated as described in Example 1 and added slowly at 20 to 25 ° 0 with good stirring to the alkaline solution.

32.6 g of 1,5-bisaeetoacetylaminonaphthalene. By addition of dilute sodium hydroxide solution, the pH of the coupling suspension is maintained between 7.5 and 10. After completion of the coupling, which lasts no more than 1 hour, the coupling suspension is acidified with hydrochloric acid to pH = 3, heated to 95 ° C. the inorganic salts are washed out of the filter cake with hot water and the aqueous cake is dried. 65.7 g of disazo dye are obtained.

208 620

Example 6

35.0 g of 2-amino-4-chlorobenzoic acid are thiolated as described in Example 2 and the diaza solution is added at 50 ° C to an aqueous suspension of 1,4-bisacetoacetylamino-2-chlorobenzene over one hour while addition of alkaline The pH of the hydroxide is maintained at between 5 and 6.5. An aqueous suspension of the passive component is prepared by adding 6 g of dodecylbenzenesulfonate to an aqueous alkaline solution of 31.1 g, 4-bisacetoacetylamino-2-chlorobenzene and acidifying with stirring to pH = 5 with stirring. the diaza is coupled and disazo dye is isolated after heating to 90 ° C. After washing, drying at 80 ° C and grinding 66.2 g of a yellow powdered dye are obtained.

Example 7

Example 6 is followed by adding 5 g of oxethylated higher aliphatic alcohol or oxethylated higher aliphatic acid instead of dodecylbenzenesulfonan.

OBJECT OF THE INVENTION

Claims (5)

A process for the preparation of disazo dyes containing two carboxyl groups in a molecule of the general formula I, COOH, COCH, I ³ 1 ³ HOOC-B-N = N-CHCONH-A-NHCOCH-N = N-B-COOH (I) wherein B is phenylene optionally substituted by chlorine, methyl, methoxy, trifluoromethyl, carbmethoxy or nitro and A is arylene a residue optionally further substituted by one or two chlorine atoms, methyl, methoxy, ethoxy, trifluoromethyl, or cyano, diazotization of the active component and subsequent coupling with the passive component in a molar ratio of 2: 1, characterized in that the coupling is carried out in aqueous medium in the pH range 3.5 to 13 at temperatures of 0 to 80 ° C and the disazo dye prepared, depending on the final pH of the coupling suspension, is isolated as the disodium salt or in the free acid form, optionally as a mixture of sodium salt and free acid. 2. The method of claim 1 wherein the coupling is performed at a pH of greater than 7 by adding the diazotized active component to the passive component. 3. The process of claim 1 wherein the coupling is performed at a pH of less than 7 by adding the diazotized active component to the passive component or vice versa. 4. The method according to claim 1, characterized by. The method according to claim 1, wherein the coupling is carried out at a pH of 13 to 3.5 by adding the diazotized active component to the passive component, or by continuously mixing the two components. 5. A process according to any one of claims 1 to 4 wherein the coupling is carried out with the addition of dispersants such as alkylarylsulfonates or polycondenzaone ethylene oxide products in an amount of 0 to 10 wt. based on the mass of the disazo dye.