GB2034738A

GB2034738A - Process for the Preparation of Azo Dyestuffs

Info

Publication number: GB2034738A
Application number: GB7937355A
Authority: GB
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1978-11-02
Filing date: 1979-10-29
Publication date: 1980-06-11
Also published as: DE2847532B2; FR2440970A1; DE2847532A1; BR7907121A; GB2034738B; CH643867A5; DE2847532C3; IN153228B; FR2440970B1; JPS5562965A

Abstract

Process for the preparation of azo dyestuffs by coupling diazo compounds with amino-naphthalene sulphamic acids or amino-hydroxy- naphthalenesulphonic acids in an acid medium in the presence of a reaction product of formaldehyde and an aromatic sulphonic acid, or a salt thereof, as the coupling accelerator.

Description

SPECIFICATION Process for the Preparation of Azo Dyestuffs The reaction of diazotised aromatic amines with components which are capable of undergoing a coupling reaction to give azo compounds is frequently carried out in the presence of coupling accelerators, such as pyridine and its homologues, formamide, dimethylformamide, urea and thiourea.

The process according to the invention, for the preparation of azo dyestuffs by coupling diazo compounds with aminohydroxy naphthalenesulphonic acids or amino naphthalene-sulphonic acids is characterised in that the coupling reaction is carried out in the presence of a reaction product of formaldehyde and an aromatic sulphonic acid, or a salt thereof, as the coupling accelerator.

Coupling accelerators which can be used according to the invention are, for example: reaction products of naphthalenesulphonic acid and formaldehyde, of (ditolyl ether)-sulphonic acid and formaldehyde, of (diphenyl ether)sulphonic acid and formaldehyde, of diphenylsulphonic acid and formaldehyde or of terphenylsulphonic acid and formaldehyde, and the said sulpho group-containing reaction products can also be in the form of water-soluble salts, especially alkali metal salts and in particular sodium salts.

The reaction products preferably employed are those which have been prepared in a known manner by reaction of 0.5-1.5 mols of an aromatic compound, such as, for example, naphthalene, ditolyl ether, diphenyl ether, diphenyl or terphenyl, with 0.5- 3 mols of sulphuric acid and a condensation reaction of the product with 0.42 mols of formaldehyde.

Compounds particularly preferentially used are

and the sodium salt of 1,1'naphthylmethanesulphonic acid.

According to the process of the invention, the coupling reaction is preferably carried out in the presence of 0.1 g to 30 g, and preferably 0.5 g to 2 g, of the reaction product of formaldehyde and the aromatic sulphonic acid per 100 ml volume of coupling mixture.

The coupling accelerator according to the invention can be partially replaced by the additional use of other coupling accelerators, such as pyridine, formamide, urea or thiourea, and, compared with the case of the use of the individual components on their own, the amounts of coupling accelerators employed can be distinctly reduced, with comparably good coupling results.

The following aminohydroxynaphthalenesulphonic acids may be mentioned by way of example: 2-amino-8hydroxy-naphthalene-6-sulphonic acid, 2-amino5-hydroxy-naphthalene-7-sulphonic acid, 1amino-8-hydroxy-naphthalene-3,6-disulphonic acid and 1 -amino-8-hydroxy-naphthalene-4,6disulphonic acid.

The following amino-naphthalenesulphonic acids may be mentioned by way of example: 1amino-naphthalene-6-sulphonic acid and 1amino-naphthalene-4-sulphonic acid.

The dyestuff yields which can be achieved by the new process are frequently higher than those from conventional processes.

A further advantage of the new process is that only small amounts of coupling accelerators have to be employed and, as a result of this, the load on the effluent due to carbon compounds can be kept low. Compared with the use of N-containing coupling accelerators, the accelerators which can be employed according to this invention have the advantage that the resulting dyestuffs cannot in some circumstances be damaged on drying, due to the elimination of NH3 from radicals of the Ncontaining compounds, say due to the decomposition of reactive groups, or become hygroscopic and aggiomerate after drying due to the presence of the radicals.

The process according to the invention can be so carried out that the reaction products of formaldehyde and an aromatic sulphonic acid are added before, during or after the diazotisation in aqueous solution or, alternatively are added to the coupling mixture.

The additional use of solubilising substances, such as glycols, diglycols and their half-ethers and also polyglycols or naphthalenesulphonic acids to stabilise the diazonium compounds is possible.

Example 1 10 g of sodium nitrite are dissolved in a solution of 48.7 g of the condensation product which is obtained by reacting 1,4- diaminobenzene-2-sulphonic acid (sodium salt) with 2,4,6-trifluoro-5-chloropyrimidine in an equimolar ratio in an aqueous, weakly alkaline medium, in 1,000 ml of water at a pH value of 7.5. This solution runs into 650 ml of 3% strength hydrochloric acid, with ice-cooling.After stirring for 2 hour, the excess nitrite is destroyed and 10 g of the condensation product of naphthalenesulphonic acid and formaldehyde (sodium salt), (obtained by sulphonation of 1 mol of naphthalene with 1.43 mols of sulphuric acid and a condensation reaction of the product with 0.65 mol of formaldehyde and subsequent neutralisation with sodium hydroxide solution) and 16 g of anhydrous sodium acetate are added.

The diazonium suspension thus obtained now runs into 300 ml of an aqueous solution which contains 35.7 g of 2-amino-8-hydroxynaphthalene-6-sulphonic acid, in the form of the sodium salt, and 12 g of anhydrous sodium acetate (pH value 6). After stirring for several hours at a pH value of 4.0-4.5 and at room temperature, the coupling reaction has ended.

The dyestuff, which has formed in very good yield, is filtered off; by-products and decomposition products remain in the aqueous filtrate.

When used for dyeing in the conventional manner, the dyestuff gives red dyeings on wool.

Example 2 59.7 g of the condensation product which is obtained by reacting 1 ,3-diamino-benzene-4sulphonic acid and 2-methylsulphonyl-4,5dichloro-6-methylpyrimidine in a molar ratio in an aqueous medium with the addition of acidbinding agents are dissolved, in the form of the Na salt, in about 600 ml of water and converted to the diazonium compound as in Example 1. After stirring for 1 hour, the excess nitrite is removed.

A solution 46.2 g of 1-amino-8-hydroxy- naphthalene-3,6-disulphonic acid, in the form of the disodium salt, and 30 g of the condensation product of naphthalenesulphonic acid/formaldehyde (sodium salt) (obtained by sulphonation of 1 mol of naphthalene with 1.43 mols of sulphuric acid and a condensation reaction of the product with 0.65 mol of formaldehyde and subsequent neutralisation with sodium hydroxide solution) in about 200 ml of water runs into this suspension at room temperature. The pH value is adjusted to 4 by allowing 300 ml of 20% strength aqueous sodium acetate solution to run in in the course of 2 hours.An aqueous suspension of the diazonium compound which is obtained by reacting 40.3 g of 1-aminobenzene-2,5-disulphonic acid with 11 g of sodium nitrite in a hydrochloric acid medium in a total volume of 500 ml at OOC is added to this reaction product at 2O230C. The pH value is adjusted to 4.5 with 90-100 ml of 20% strength aqueous sodium carbonate solution. After stirring for 1 hour, the disazo dyestuff formed can be precipitated in good yield by adding sodium chloride in an amount of 20-25% of the end voiume.

An aqueous solution of this dyestuff, with the addition of acid-binding agents, can be applied to a cotton sample. After thermofixing in a known manner, blue-black dyeings which are fast to washing are obtained.

A similarly good result from the dyestuff preparation is obtained if only half of the abovementioned amount of the naphthalenesulphonic acid/formaldehyde condensation product and 65 g of urea or formamide are added to the coupling batch.

Example 3 59.3 g of 1-amino-4-nitrobenzene-2carboxylic acid are dissolved, in the form of the sodium salt, in about 600 ml of water at 850C. 10 g of the condensation product of naphthalenesulphonic acid and formaldehyde, in the form of the sodium salt, (obtained by sulphonation of 1 mol of naphthalene with 1.43 mols of sulphuric acid and a condensation reaction of the product with 0.65 mol of formaldehyde and subsequent neutraiisation with sodium hydroxide solution), 5 g of naphthalene1,5-disulphonic acid (Armstrong's acid) and 94 ml of 36% strength hydrochloric acid are added to this solution. After stirring for several hours, the suspension is diazotised at 30-350C by adding 76.6 ml of a 30% strength aqueous solution of sodium nitrite.

A warm solution, at about 400 C, of 69.3 g of 2-amino-5-hydroxy-naphthalene-7-sulphonic acid, in the form of the sodium salt, in 600 mi of water, to which 1 0 g of the abovementioned naphthalenesulphonic acid/formaidehyde condensation product have been added, runs into this suspension, which has been cooled to OOC and freed from excess nitrous acid. After stirring for several hours at room temperature, the monoazo dyestuff, which has formed in about 80% yield, is filtered off.

The resulting monoazo dyestuff can bused, inter alia, to prepare the metallisable trisazo dyestuff described below.

26.5 g of 4,4'-diamino-3,3'dimethoxydiphenyl are converted to the bisdiazonium compound in a known manner, in an aqueous hydrochloric acid medium using sodium nitrite. 600 ml of a pale yellow, clear solution are obtained.

47.6 g of the abovementioned monoazo dyestuff and 60 g of sodium carbonate are brought into solution in 300 ml of water by warming. This solution runs into the cold bisdiazonium solution. A dark precipitate forms. 400 ml of an aqueous solution which contains 26 g of 2-hydroxy-naphthalene-6-sulphonic acid in the form of the sodium salt are then added. The pH value is adjusted to 11-12 with sodium hydroxide solution.

After stirring for several hours, the coupling reaction has ended. The trisazo dyestuff formed can be precipitated from the resulting solution by adding sodium chloride in an amount of about 6% of the volume, and filtered off.

The dyestuff gives blue dyeings on cellulose material and the fastness to light and washing of these dyeings can be increased by after-treatment with copper salt solutions.

Claims

1. A process for the production of an azo dyestuff by coupling a diazo compound with an aminohydroxynaphthalene-sulphonic acid or an amino-naphthalenesulphonic acid in an acid medium, in which the coupling reaction is carried out in the presence of a reaction product of formaldehyde and an aromatic sulphonic acid, or a salt thereof, as the coupling accelerator.

2. A process according to claim 1, in which the coupling reaction is carried out in the presence of a reaction product of naphthalenesulphonic acid and formaldehyde, of (ditolyl ether)-sulphonic acid and formaldehyde, of (diphenyl ether)sulphonic acid and formaldehyde, of diphenylsulphoric acid and formaldehyde or of terphenylsulphonic acid and formaldehyde, or a water-soluble salt thereof.

3. A process according to claim 1 or 2, in which the reaction product of an aromatic sulphonic acid and formaldehyde has been prepared by reacting 0.5 to 1.5 mols of an aromatic compound with 0.5 to 3 mols of sulphuric acid and subjecting the product to a condensation reaction with 0.4 to 2 mols of formaldehyde.

4. A process according to any of the foregoing claims in which the coupling accelerator is a compound of the formula

or the sodium salt of 1,1'naphthylmethanesulphonic acid.

5. A process according to any of the foregoing claims in which the coupling reaction is carried out in the presence of 0.1 g to 30 g of the reaction product of formaldehyde and the aromatic sulphonic acid per 100 ml of coupling mixture.