DD274025A5 - PROCESS FOR PREPARING 4,4'-DINITROSTILENE-2,2'-DISULPHONIC ACID - Google Patents

Abstract

The invention relates to a process for the preparation of 4,4-dinitrostilbene-2,2-disulfonsaeure by oxidation of 4-nitrotoluene-2-sulfonic acid using liquid, anhydrous ammonia, liquid alkyl derivative of ammonia or a mixture of ammonia and / or the Alkyl derivatives of ammonia with water as a solvent.

Description

27402s

Process for the preparation of 4,4'-dinitro-8-tril-2,2'-disulphonic acid

Field of application of the invention

The process according to the invention is used in the field of chemistry.

Characteristic of the known state of the art

Processes for the industrial preparation of 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNS) and its salts are well known and consist in the oxidative condensation of 2 moles of 4-nitrotoluene-2-sulfone acid (p-NTSA) under aqueous alkaline conditions according to the old methods developed at the end of the last century. As oxidizing agents, oxygen (air) in the presence of a catalyst or sodium hypochlorite are described (see, for example, BAG Green and AR Wahl, Chemische Berichte 30, 3097-3101 (1897); 31, 1079 (1898); DRP 106,961; Chemisches Zentralblatt 1900 I , 1085; DRP 113,514 and Chemisches Zentralblatt 1900 II, 703). However, these processes provide the 4,4'-dinitrostilbene-2,2'-dlsulfonic acid and its salts, despite modern technical improvements, only in relatively poor yields, which are between 60 and 75 % (see, for example, DE-OS 22 58 530).

In the last 25 years, therefore, many efforts have been made to the yield of this condensation

using physico-chemical, mathematical and analytical methods as well as computer models. However, these efforts did not lead to any significant success (see, for example, CA 8525, 113377 (1975); CA 85, 192. 288 z, 192.289a, 192.290 (1976), CA 86, 16029c (1977) Chimie Analytique 50, 251-254 (1968) and Chimie et Industrie, Genie Chimique 101, 1439-1447 (1969)).

Particularly noteworthy are the efforts made in the last 10 years, which had virtually all the aim of the major environmental problems, such. B. the non-biodegradable mother liquors, by optimizing the yield to solve «

Thus, according to the DDR patent 240200, the aqueous air oxidation of 4-nitrotoluene-2-sulfonic acid is carried out in two stages at two different temperatures and two different alkali concentrations, wherein in the first stage, the 4,4'-dinitrodibenzyl-2,2'-disulfonic acid to Part fails. The yields of 4.4 ^l -Dinitrostilben-2,2'-disulfonic acid are given with 82 to 85 % of theory, but without information about the quality of the product obtained.

From DE-OS-3409171 a process is known which carries out the aqueous air oxidation of 4-nitrotoluene-2-sulfonic acid in the presence of lithium and hydroxyl ions, optionally with the addition of a catalyst. The yields of 4,4'-dinitrostilbene-2,2'-disulfonic acid are reported to be about 80 to 90 % of theory. A disadvantage of this process is the additional step of separating lithium as lithium carbonate prior to the isolation of 4,4'-dinitrostilbene-2,2'-disulfonic acid, wherein the recovery of the

Lithium carbonates is only 75 to 83 % . In addition, the recovered lithium carbonate must first be converted to lithium hydroxide "before it can be reused in the process.

In the German patent application 3519552 a process for the preparation of 4.4 ^l -Dinitrostilban-2,2'-disulfonsäuresalzen by aqueous air oxidation of 4-nitrotoluene-2-sulfonic acid is described ι which is characterized in that during the reaction potassium « Calcium and / or magnesium ions added as 4,4'-dinitrostilbene-2,2'-disulfonic acid is formed, wherein at any time of the reaction, the amount of added potassium, calcium and / or magnesium ions IO to 150 Mcl-%, based on the amount of 4,4'-dinitrostilbene-2,2'-disulfonic acid present in the reaction mixture, and the precipitated salt of 4,4'-dinitrostilbene-2,2'-di3ulfonsäure separates. A disadvantage of this process is the workup and disposal of the large amounts of base and the potassium, calcium and magnesium salts added in large quantities.

European Offenlegungsschrift 2,6154 describes a process for the preparation of 4,4'-dinitrostilbene-2,2'-disulphonic acid and its salts by the air-oxidation of 4-nitro-toluene-2-sulphonic acid in organic solvents. Depending on the mode of operation, yields of up to 96 % of theory are achieved by this process. A disadvantage of this method is the work in aprotic dipolar solvents whose recovery is complicated and, as is known, can not be performed without losses.

Object of the invention

The invention provides a process for the preparation of 4,4'-dinitrostilbene-2,2'-disulphonic acid and its salts in high yields and while avoiding the disadvantages mentioned above.

Explanation of the essence of the invention

The invention has for its object to provide a process for the preparation of 4.4 ^l -Dinitrostilben-2,2'-disulfonic acid and salts thereof.

It has now been found that 4,4 * -dinitrostilbene-2,2'-disulfonic acid (DNS) and its salts in high yields and while avoiding the disadvantages mentioned above, surprisingly by oxidation of 4-nitrotoluene-2-sulfonic acid with an oxidizing agent can be prepared by carrying out the oxidation in liquid, anhydrous ammonia, the alkyl derivative optionally in the presence of water and / or mixtures thereof with each other.

The subject of the application is thus a process for the preparation of 4,4'-dinitrostilbene-2, 2'-disulfonic acid and salts thereof of the formula

SO, M

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wherein M represents hydrogen "an alkali metal cation or an ammonium cation, by oxidation of 4-nitrotoluene-2-sulfonic acid or its salts with an oxidizing agent" characterized in that the oxidation in liquid "anhydrous ammonia" of its alkyl derivative optionally in the presence of water and / or mixtures thereof with each other and in the presence of strong bases and optionally of catalysts.

The 4-nitrotoluene-2-sulfonic acid (p-NTSA) or its alkali and ammonium salts used as starting material is a compound known in the chemical industry which is very easily prepared by sulfonation of 4-nitrotoluene. It can be used either as a free acid or as one of its known salts. These salts may be present either in dry form or preferably as wet presscake with a water content of 1 to 50%, preferably 1 to 25% or other precursor such as the synthesis solution or suspension, the concentrated aqueous preparation, as hydrous OeI or as a dry powder be used.

Liquid, anhydrous ammonia, the alkyl derivative of which is optionally used in the presence of water and / or mixtures thereof as the reaction medium in the present process according to the invention, are understood to mean, in particular, the following solvents or combinations:

a) anhydrous, liquid ammonia

b) anhydrous, liquid alkyl derivative of ammonia

c) mixture of a) and b)

d) ammonia and water,

e) alkyl derivative of ammonia and water,

f) ammonia and an alkyl derivative of ammonia and water.

Preferably, the combination d).

Both the starting 4-nitrotoluene-2-sulfonic acid and the intermediate 4,4'-dinitrodibenzyl-2,2'-disulfonic acid and the reaction product 4,4'-dinitrostilbene-2,2'-disulfonic acid are e.g. among the reaction media mentioned in this process, in the abovementioned solvents or combinations a) to f) and especially in the combination d) more soluble than in water or aprotic dipolar solvents. As a result, the reaction occurring today in industry in great dilution may be much more concentrated e.g. already with a part of one of the solvents mentioned or combination a) to f) per part of 4-nitrotoluene-2-sulfonic acid, preferably with 1-10 parts and in particular 3-6 parts of one of the solvents mentioned above.

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medium or combination a) to f) are carried out; a circumstance which is of great technical and economic advantage. Furthermore, ammonia is cheap and easily accessible from a technical standpoint. Thanks to its low boiling point (-33.35 ° C at 760 Torr) and its excellent stability under the reaction conditions mentioned in this process, it can be recovered virtually quantitatively and can thus be recycled back into the process.

Suitable alkyl derivatives of the ammonia are both primary and secondary and tertiary amines of the following formulas:

CH ".. CH ₀ ,. CH "...

η 2n + l \ η 2n + l \ η 2n + l \

H ^ NCH _0. , - ^ NCH _0. , - ^ N

y η 2n + l / η 2n + l /

η π C H-,

η 2η + 1

In these formulas, η means above all the numbers 1 to 6 which are both uniform amines (e.g., dimethylamine) and mixed amines (e.g., ethyldimethylamine). Particularly preferred are dimethylamine, triraethylamine, Aethylarain, diethylamine, triethylamine and especially methylamine.

The combinations d) to f) used as reaction solvents in the process according to the invention preferably contain from 50 to 99% and in particular from 60 to 80% of ammonia and / or an alkyl derivative of ammonia, based on the total amount of the corresponding combination. The ratio of water to ammonia can be adjusted in various ways, e.g. by mixing water, an aqueous ammonia solution with e.g. J to 30% ammonia content, aqueous 4-nitrotoluene-2-sulfonic acid or its salts or liquid ammonia and then the missing parts of ammonia, water, dissolved in water base, Ammoniakwasset or AJ.kylderivate the ammonia.

Particularly suitable bases are the alkali or alkaline earth metals, wio lithium, sodium, potassium, magnesium and calcium, and their strongly basic compounds, e.g. Hydroxides, amides, alcoholates, and strongly basic ion exchangers.

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Alcoholates are essentially those which are derived from open-chain, branched or cyclic lower aliphatic alcohols having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms such as methanol, ethanol, propanol, butanol, isopropanol and tert-butanol. These alcoholates are preferably used in the form of the corresponding alcoholic solution.

Preferably, sodium or potassium compounds are used, their hydroxides and alcoholates are of particular practical importance.

Depending on the type and amount of base used, it is advantageous to use the base dissolved in a protic solvent. The protic solvents used are preferably water or open-chain, branched or cyclic low molecular weight aliphatic alcohols having 1 to 8 carbon atoms. Of particular importance is the use of methanol and / or water.

The base can be presented in the implementation of the oxidation either in the reaction vessel, wherein the'p-NTSA is added or dosed simultaneously with p-NTSA but via separate metering units, or alone to the submitted p-NTSA are added.

The amount of base to be used can vary within wide limits. In the presence of a catalyst, catalytic amounts can be used because the base regenerates in the course of the reaction. Preferably, however, based on p-NTSA, between catalytically and equivalently present amounts of base, in particular 0.25 to 0.5 mol. If the oxidation is carried out without a catalyst, at least equivalent amounts of base are used based on p-NTSA. However, the optimal amount of base added can easily be determined by preliminary tests.

Suitable catalysts are salts, oxides or hydroxides of heavy metal compounds and / or heavy organometallic compounds, such as e.g. those of Co, Mn, Cr, Ce, Fe, Ni, Cu, Ru, Pd, Pt or Ir are suitable (cf., for example, Homogeneous Catalysis by Metal Complexes, Vol. I, Chapter 2: Activation of molecular oxygen, page 79, Academic Press New York and

London 1974). Of particular importance as catalysts, however, are the salts, oxides or hydroxides of manganese and / or the organometallic compounds, e.g. Manganese sulfate and / or manganese acetate.

Inorganic or organic bromine and / or iodine compounds such as e.g. NaJ, KJ, KBr and Aramonxumbromide can also be used to advantage.

In addition, phase transfer catalysts or crown ethers may additionally be used, especially in those cases in which the strong bases to be used have insufficient solubility in liquid ammonia.

Examples of phase transfer catalysts are: ammonium chloride, aramonium bromide, methylamine hydrochloride, cyclohexylamine hydrochloride, aniline hydrochloride, dimethylamine hydrochloride, di-isobutylamino hydrochloride, triethylamine hydrochloride, triethylamine hydrobromide, tri-n-octylamine hydrochloride, benzyl-dimethylarain hydrochloride, tetramethyl, tetraethyl, tetra-n-propyl, tetraethyl n-butylammonium chloride, bromide and iodide, trimethylhexadecylammonium chloride, benzyldimethylhexadecylaramonium chloride, benzyldimethyltetradecylammonium chloride, benzyltrimethyl-, triethyl- and tri-n-butylammonium chloride, n-butyl-tri-n-propylaramonium bromide, octadecyltrimethylammonium bromide, phenyltrimethylammonium bromide or chloride, hexadecylpyridiniurabromide and chloride.

Examples of crown ethers are: 15-Crown-5; 18-crown-6; Dibenzo-18-crown-6; Dicyclohexyl-ie-crown-o; 5,6,14,15-dibenzo-7,13-diaza-l, 4-dien-dioxacyclopentadeca-S.M.

The amount of catalysts used can vary within wide limits. In some cases, it is sufficient if the catalysts are present in traces. In general, however, the catalysts are preferably used in an amount of about 0.1 to 15 weight percent, based on the 4-nitrotoluene-2-sulfonic acid or salts thereof.

The reaction temperature is generally not critical and may be between -33 ° C and + 5O ⁰ C, but preferably it is between -15 ° C and 3O ⁰ C, in particular between 0 ⁰ C and 25 ° C. Will the reaction be added

-33 ° C, then it takes place under atmospheric pressure. At higher temperatures, the reaction must be carried out in the vapor pressure of the liquid ammonia, the alkyl derivative, which is known in the literature (Encyclopedia of Chemical Technology, Third Edition, Volume 2, Page 524; Ullmanns Encyklopadie der technischen Chemie, 1933, Volume 3, page 524) of the ammonia or the respective mixture of ammonia and / or alkyl derivative of the ammonia are carried out with water.

The oxidizing agents are pure oxygen or its mixtures with inert gases, e.g. Nitrogen, and air in question. The oxidizing agents are used in excess of p-NTSA. In general, an excess of about 300%, preferably 50% to 100%, based on p-NTSA is used. Of particular practical importance is the use of pure oxygen in a closed circuit, whereby the used oxygen is constantly replaced.

In a preferred embodiment, 1 part of 4-nitrotoluene-2-sulfonic acid or its salts is suspended in the form of the moist press cake with a catalytic amount of manganese II salt such as manganese sulfate and / or manganese acetate in 0.5 to 3 parts aqueous ammonia solution or water , with 1 to 5 parts of liquid ammonia, so that the ammonia content of the entire reaction mixture is 60% to 80% and in the presence of oxygen as the oxidizing agent and sodium hydroxide as the base, at temperatures of 0-25 ⁰ C and under pressure, implemented. The workup is carried out in a known manner.

The inventive method provides the 4,4'-dinitrostilbene-2,2'-disulfonic acid or salts thereof in almost quantitative yield and high purity, without causing colored by-products.

Another advantage of the method is the fact that the DNA prepared according to the invention directly without additional purification and when using liquid ammonia without further work to (4-amino-4'-nitro) -stilbene-2,2'-disulfonic acid and 4,4'-diaminostilbene-2,2'-disulfonic acid, one for the production of dyes and

optical brighteners important intermediate product «can be reduced. This reduction takes place in a manner known per se with hydrogen in the presence of catalysts.

The following examples illustrate the invention without being limited thereto. Parts and percentages are by weight or by weight.

embodiments

Example 1 : in a 11 BUECHI glass autoclave equipped with a cooling / heating jacket, pressure gauge, gassing stirrer, thermometer, dropping funnel, immersion gassing tube, two one-way valves and two rotameters for introducing and discharging oxygen and rupture disc (10 bar) at atmospheric pressure and at -40 ⁰ C, 97.0 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6 %) , · Introduced 4.5 g of manganese (II) acetate tetrahydrate and 360 g of liquid ammonia - this corresponds to a ratio from 1 part p-NTSA Na salt to 3.8 parts ammonia. The autoclave is closed and the internal temperature of -33.3 ⁰ C increased to +5 ⁰ C while the internal pressure rises to 4 bar.

In the obtained clear solution, an oxygen atom of 10 l / h, is introduced at a stirring speed of 600 to 700 rpm. In addition, 21.6 g of a methanolic 30% sodium methylate solution are added over 20 minutes at an internal temperature of 5 to 7 C. The resulting reaction mixture is then stirred for one hour and 40 minutes at 5 ⁰ C while introducing oxygen (10 l / h).

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For working up, the internal pressure in the autoclave is lowered bar by partial evaporation of the ammonia from 4 to atmospheric pressure, "while the Innentampt ^<0 temperature of +5 C to -27 ⁰ C. drops are then added to the reaction mixture at atmospheric pressure with 6,5 g Ammonium chloride and slowly diluted with 400 vl of methanol, while the reaction product precipitates crystalline. The oxygen stream is turned off and the resulting suspension is freed from ammonia by slow heating to + 30 ⁰ C. The stirrer is switched off and the autoclave is unloaded.

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The reaction mixture is then evaporated to dryness in vacuo, taken up in 2 l of water, made alkaline with 200 ml of 2N sodium hydroxide, neutralized with 200 ml of 2N hydrochloric acid, freed from the catalyst by filtration and the resulting pale yellow solution is concentrated to dryness in vacuo. The residue is taken up in 300 ml of water and from this the reaction product is precipitated by addition of 34 g of sodium chloride, filtered with suction, washed with 100 ml of a 7.5% isene sodium chloride solution and dried to constant weight under vacuum at HO ⁰ C. This gives 95.0 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a light yellow crystalline powder of melting point above 300 ⁰ C, which has an active content (UV spectrophotometrically determined) of 94.0%. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 94.1% of theory. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt determined by LC analysis is 93.6% of theory.

Example 2; In ednem glass autoclave gemä'ss Example 1 are at atmospheric pressure and at -40 ⁰ C, 97.0 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 3.1 g of manganese (II) - submitted to sulfate monohydrate and 360 g of liquid ammonia - this corresponds to a ratio of 1 part p-NTSA-Na salt to 3.8 parts of ammonia. The autoclave is closed and the internal temperature of -33.3 ⁰ C increased to +15 ⁰ C while the internal pressure rises to 6 bar.

In the resulting clear solution, an oxygen flow of 10 l / h, initiated at a stirring speed of 600 to 700 rpm. In addition, 11 g of a 30% methanolic Natriuramethylat solution are added within 25 minutes at an internal temperature of 15 ° C. The resulting reaction mixture is then stirred for an hour and 35 minutes at 15 ⁰ C while introducing oxygen (10 l / h).

The work-up is carried out as described in Example 1, with the exception that the reaction mixture is admixed with 4.5 g of ammonium chloride. This gives 96.2 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a pale yellow crystalline powder with a melting point above 300 ⁰ C,

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which has an active content (determined by UV spectrophotometry) of 91.7%. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 93.0% of theory.

Similar results are obtained by carrying out the reaction in a ratio of 1 part of p-NTSA-Na salt to 2.5 parts of ammonia.

Example 3; In a 11 BUECHI glass autoclave equipped with a cooling / heating jacket, pressure gauge, gassing stirrer, thermometer, dropping funnel, gassing tube above level, two one-way valves and two rotameters for introducing and removing oxygen and rupture disc (10 bar) at atmospheric pressure and at -40 ⁰ C, 97.0 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), submitted 4.6 g of manganese (II) nitrate tetrahydrate and 375 g of liquid ammonia - this corresponds to a ratio of 1 part p-NTSA-Na salt to 3.9 parts ammonia. The autoclave is closed and the internal temperature increased from -33.3 ° C to +15 ⁰ C while the internal pressure rises to 6 bar.

Above the level of the clear solution obtained, an oxygen current of 13 l / h is introduced at a stirring speed of 600 to 700 rpm. In addition, a solution of 4.8 g of sodium hydroxide in 24 g of methanol is added over 30 minutes at an internal temperature of 15 ° C. The resulting Reaktiohsgemisch is then stirred for an hour at 15 ° C while introducing oxygen (13 l / h).

The work-up is carried out as described in Example 1. This gives 97.2 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a light yellow crystalline powder of melting point above 300 ⁰ C, which has an active content (UV spectrophotometrically determined) of 89.1 % . The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 91.3% of theory.

EXAMPLE 4 In a glass autoclave according to Example 3, 97.0 g of 4-mitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 4.5 g of manganese (II) are added at atmospheric pressure and at -40 ° C. acetate tetrahydrate

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and submitted 360 g of liquid ammonia. The autoclave is closed and the internal temperature increased from -33.3 ° C to +15 ⁰ C while the internal pressure rises to 6 bar.

About level of the obtained clear solution, an oxygen flow of 13 l / h, is introduced at a stirring speed of 600 to 700 rpm. In addition, 19.2 g of a 50% aqueous sodium hydroxide solution are added over 15 minutes at an internal temperature of 15 ° C. The resulting reaction mixture containing an ammonia / water Geroisch of 97.5% ammonia to 2.5% water (this corresponds to a ratio of 1 part p-NTSA-Na salt to 3.9 parts solvent mixture) is now one hour and 15 Stirred minutes at 15 ° C while introducing oxygen (13 l / h).

The work-up is carried out as described in Example 1. This gives "95.2 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a light yellow crystalline powder of melting point above 300 ⁰ C, which has an active content (UV spectrophotometrically determined) of 93.5% The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 93.8% of theory The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt determined by LC analysis is 92 , 8% of theory.

Example 5; In a glass autoclave gem'ass example 1 at atmospheric pressure and at -4O ⁰ C, 97.0 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 4.5 g of manganese (II) - acetate tetrahydrate and 360 g of liquid ammonia submitted. The autoclave is closed and the internal temperature of -33.3 ⁰ C increased to +15 ⁰ C while the internal pressure rises to 6 bar.

In the resulting clear solution, an oxygen flow of 13 l / h, is introduced at a stirring speed of 600 to 700 rpm. In addition, 16.0 g of an aqueous 30% sodium hydroxide solution are added within 15 minutes at an internal temperature of 15 to 17 ° C. The resulting reaction mixture containing an ammonia / water mixture of 97% ammonia and 3% water (this corresponds to a ratio of 1 part p-NTSA-Na salt to 3.9 parts solvent mixture) is now 45 minutes at 15 ° C with introduction further stirred by oxygen (13 l / h).

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The working up is as in Example 1. This gives 97.0 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid Dinatriumsale in the form of a pale yellow crystalline powder with a melting point above 300 ⁰ C _1, an active content (determined by UV spectrophotometry) of 92.2%. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 94.3% of theory. The yield of 4,4'-dinitrostilbene-2,2'-disulphonic acid dinatriura salt determined by LC analysis is 95.0% of theory.

Example 6: In a glass autoclave according to Example 3 are at atmospheric pressure and at -40 ⁰ C, 97.0 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 3.1 g of manganese (II) sulfate monohydrate and 360 g of liquid ammonia submitted. The autoclave is closed and the internal temperature increased from -33.3 ° C to +15 ⁰ C while the internal pressure rises to 6 bar.

About level of the obtained clear solution, an oxygen flow of 13 l / h, is introduced at a stirring speed of 600 to 700 rpm. In addition, 32 g of a 15% aqueous sodium hydroxide solution are added within 15 minutes at an internal temperature of 15 ° C to 17 ⁰ C. The resulting reaction mixture containing a Aramoniak / water mixture of 93% ammonia and 7% water (this corresponds to a ratio of 1 part p-NTSA-Na salt to 4.1 parts solvent mixture) is now 45 minutes at 15 ° C with introduction further stirred by oxygen (13 l / h).

The work-up is carried out as described in Example 1. This gives 94.4 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a pale yellow crystalline powder with a melting point above 300 ⁰ C, which has an active content (UEV determined spectrophotometrically) of 96.1%. Dio yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 95.6% of theory. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt of the reaction mixture before workup, determined by LC analysis is 96.4% of theory.

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Example 7; In a glass autoclave according to Example 3, 97.0 g of 4-nitrotoluene-2-sulfonic acid Natriurasalz (active content: 98.6%), 4.6 g of manganese (II) nitrate tetrahydrate at atmospheric pressure and at -4O ⁰ C. and submitted 360 g of liquid ammonia. The autoclave is closed and the internal temperature of -33.3 ° C to +15 ⁰ C increases while the 'internal pressure rises to 6 bar.

About level of the obtained clear solution, an oxygen flow of 13 l / h, is introduced at a stirring speed of 600 to 700 rpm. In addition, 64 of a 7.5% β lgen aqueous sodium hydroxide solution within 15 minutes at an internal temperature of 15 ° C to 2O ⁰ C are added. The resulting reaction mixture containing an ammonia / water mixture of 86 % ammonia with 14% V / asser (this corresponds to a ratio of 1 part p-NTSA-Na salt to 4.4 parts solvent mixture) is now 45 minutes at 15 ° C. while passing in oxygen (13 l / h).

The work-up is carried out as described in Example 1. This gives 93.4 g of 4.4 ^{<dinitrostilbene-2,2'-disulfonic} acid disodium salt in the form of a pale yellow crystalline powder with a melting point above 300 ⁰ C, which has an active content (determined by UV spectrophotometry) of 96.9%. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 95.4% of theory. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt determined by LC analysis is 94.7% of theory.

Example 8: In a glass autoclave according to Example 3 are at atmospheric pressure 77.6 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 1.6 g of manganese (II) acetate tetrahydrate and 66 g of a Submitted to 25% aqueous ammonia solution. The autoclave is closed and at an innerenterature of 15 ° C., 242 g of liquid ammonia are added, the internal pressure rising to 4.4 bar.

Above the level of the clear solution obtained, an oxygen flow of 10 l / h is introduced at a stirring speed of 600 to 700 rpm. In addition, 42.7 g of a 30% aqueous sodium hydroxide solution within 20 minutes at an internal temperature of 15 ⁰ C to 17 ° C is added. The resulting reaction mixture containing an ammonia / water

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Mixture of 76.5% ammonia and 23.5% water (this corresponds to a ratio of 1 part p-NISA-Na salt to A, 4 parts Lösungsmitiielgemisch) is now two hours at 15 ° C while introducing oxygen (10 l / h).

The workup is carried out as described in Example 1 with the exception that the reaction mixture is mixed with 17 g of ammonium chloride and diluted with 100 ml of water instead of methanol. This gives 75.4 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a pale yellow crystalline powder with a melting point above 300 ⁰ C, which has an active content (determined by UV spectrophotometry) of 96.7%. The. Yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 96.0% of theory. The yield of 4,4-dinitrostilbene-2,2'-disulfonic acid disodium salt of the reaction mixture before the workup, determined by LC analysis is 96.5% of theory.

Example 9: In an autoclave according to Example 1 at atmospheric pressure and at -4O ⁰ C, 97.0 g of 4-mitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 94.4 g of water, 4.5 g manganese (II) acetate tetrahydrate and 266 g of liquid ammonia submitted. The autoclave is closed and the internal temperature of -33.3 ⁰ C increased to +13 ⁰ C while the internal pressure rises to 3.3 bar.

In the resulting clear solution, an oxygen flow of 10 l / h, initiated at a stirring speed of 600 to 700 rpm. In addition, 16.0 g of an aqueous 30% sodium hydroxide solution within 15 minutes at an internal temperature of 13 to 15 ⁰ C added. The resulting reaction mixture containing an ammonia / water mixture of 71.5% ammonia and 28.5% water (this corresponds to a ratio of 1 part p-NTSA-Na salt to 3.9 parts solvent mixture) is now one hour at 15 C. while stirring in oxygen (10 l / h).

The workup is carried out as described in Example 1, wherein instead of 400 ml of methanol, 300 ml of water are used. This gives 96.3 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a light yellow crystalline powder of melting point above 300 ° C., which has an active content (determined by UV spectrophotometry) of 91.6%.

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has. The yield of 4,4'-dinitrostilbene-2,2'-disulphonic acid dinatriuin salt is 93.0% of theory. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt determined by LC analysis is 92.8% of theory.

Are used instead of 97.0 g of 4-nitrotoluene-2-sulfonic acid sodium salt, 115.1 g of this compound as a moist press cake (active content: 83.1%, water content: 15.7%) and correspondingly 76.3 g of water you get the same results.

Example 10 In a glass autoclave according to Example 3, 97.0 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 2 g of manganese (II) acetate tetrahydrate and 195 g of a 25% are obtained at atmospheric pressure. submitted aqueous ammonia solution. The autoclave is closed and at an internal temperature of 15 ° C, 210 g of liquid ammonia are added, the internal pressure rises to 2.6 bar.

The preferred level of the clear solution obtained, an oxygen flow of 10 l / h, initiated at a stirring speed of 600 to 700 rpm. In addition, 26.7 g of a 30% aqueous sodium hydroxide solution within 20 minutes at an internal temperature of 10 ⁰ C to 15 ⁰ C added. The resulting reaction mixture containing an ammonia / water mixture of 61% ammonia and 39% water (this corresponds to a ratio of 1 part p-NTSA-Na salt to 4.4 parts solvent mixture) is now two hours at 15 ° C with introduction of oxygen (10 l / h) weiterger ' ^: ' »rt.

The work-up is carried out as described in Example 1 with the exception that the reaction mixture is mixed with 11 g of ammonium chloride and diluted with 100 ml of water instead of methanol. This gives 95.4 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in Fono a light yellow crystalline powder with a melting point of about 30Q ° _C: having an active content (determined by UV spectrophotometry) of 92.4% having , The yield of 4,4'-dinitrop.tilben-2,2'-disulfonic acid disodium salt is 92.9% of theory. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt of the reaction mixture before workup, determined by LC analysis is 95.7% of theory.

- 17 -

η i 025

If instead of 97.0 g of 4-nitrotoluene-2-sulfonic acid sodium salt, 115.1 g of this compound as a moist press cake (active content: 83.1%, water content: 15.7%) and correspondingly 171 g of a 25% aqueous ammonia Solution and 216 g of liquid ammonia are used, the same results are obtained.

Example 11: In a glass autoclave according to Example 3 are at atmospheric pressure 77.6 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 1.6 g of manganese (II) acetate tetrahydrate and 202 g of a Submitted to 25% aqueous ammonia solution. The autoclave is closed and at an internal temperature of 20 ⁰ C, 210 g of liquid ammonia are then added, the internal pressure rises to 4 bar.

Above the level of the clear solution obtained, an oxygen current of 10 l / h is introduced at a stirring speed of 600 to 700 rpm. In addition, 21.3 g of a 30% aqueous sodium hydroxide solution within 20 minutes at an internal temperature of 18 ⁰ C to 2O ⁰ C added. The resulting reaction mixture containing an ammonia / water mixture of 61% ammonia and 39% water (this corresponds to a ratio of 1 part p-NTSA-Na salt to 5.6 parts solvent mixture) is now two hours at 20 ⁰ C with introduction of oxygen (10 l / h) further stirred.

The work-up is carried out as described in Example 1 with the exception that the reaction mixture is mixed with 9 g of ammonium chloride and diluted with 100 ml of water instead of methanol. This gives 76.8 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a pale yellow crystalline powder with a melting point above 300 ⁰ C, which has an active content (determined by UV spectrophotometry) of 94.8%. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 95.9% of theory. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt of the reaction mixture before workup, determined by LC analysis is 96.5% of theory.

- 18 -

Similar results are obtained by carrying out the reaction in a ratio of 1 part of p-NTSA-Na salt to 8 parts of solvent mixture.

Example 12: In a glass autoclave according to Example 3 are at atmospheric pressure 77.6 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 1.6 g of manganese (II) acetate tetrahydrate and 148 g of a Submitted to 25% aqueous ammonia solution. The autoclave is closed and 172 g of liquid ammonia are now added at an innerenterature of 15 ° C., the internal pressure rising to 3.5 bar.

The preferred level of the clear solution obtained, an oxygen flow of 10 l / h, initiated at a stirring speed of 600 to 700 rpm. In addition, 32 g of a 30% aqueous sodium hydroxide solution are added over 20 minutes at an internal temperature of 10 ⁰ C to 15 ° C. The resulting reaction mixture containing an ammonia / water mixture of 61 % ammonia and 39 % water (this corresponds to a ratio of 1 part p-NTSA-Na salt to 4.5 parts solvent mixture) is now two hours at 15 ° C with introduction of oxygen (10 l / h) further stirred.

The workup is carried out as described in Example 1 with the exception that the reaction mixture is mixed with 12.8 g of ammonium chloride and diluted with 100 ml of water instead of methanol. This gives 78.2 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a pale yellow crystalline powder with a melting point above 300 ⁰ C, which has an active content (determined by UV spectrophotometry) of 93.4%. The yield of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 96.2% of theory. The yield of 4,4'-dinitrostilbene-2,2 ^l -disulfonic acid disodium salt of the reaction mixture before workup, determined by LC analysis is 97.3% of theory.

Example 13 In a glass autoclave according to Example 3, 97.7 g of 4-nitrotoluene-2-sulfonic acid (active content: 73.4%, water content: 18.2%, sulfuric acid content: 8.4 X) and 1.6 are obtained at atmospheric pressure g manganese (II) acetate tetrahydrate submitted. The autoclave is closed and at an internal temperature of 2O ⁰ C to 24 ⁰ C within

- 19 -

25 minutes 257 g of liquid ammonia added, the internal pressure rises to 5.6 bar. The reaction mixture is then added at an internal temperature of 1O ⁰ C to 15 ° C within 15 minutes with 64.8 g of a 30% aqueous sodium hydroxide solution.

Over level of the obtained clear solution, an oxygen flow of 10 l / h, is introduced at a stirring speed of 600 to 700 rpm. In addition, 21.3 g of a 30% aqueous sodium hydroxide solution within 20 minutes at an internal temperature of 15 ° C to 20 ⁰ C added. The resulting reaction mixture containing an ammonia / water mixture of 77% ammonia and 23% water (this corresponds to a ratio of 1 part p-NTSA to 4.7 parts solvent mixture) is now two hours at 15 ° C while introducing oxygen (10 l / h).

The work-up is carried out as described in Example 1 with the exception that the reaction mixture is mixed with 8.6 g of ammonium chloride and diluted with 100 ml of water instead of methanol. This gives 76.1 g of 4,4'-dinitrostilbene-2,2'-disulfonaäure-disodium salt in the form of a light yellow crystalline powder with a melting point above 300 ⁰ C, the an active content (determined by UV spectrophotometry) of 93.8% having , The yield of 4, Λ'-dinitrostilbene-2,2'-disulfonic acid disodium salt is 94.0% of theory. The yield of 4,4'-dinitrostilbene-2,2 ^l -disulfonic acid disodium salt of the reaction mixture before workup, determined by LC analysis is 94.5% of theory.

Example 14: In a glass autoclave according to Example 3 are at atmospheric pressure and at -1O ⁰ C, 77.6 g of 4-nitrotoluene-2-sulfonic acid sodium salt (active content: 98.6%), 3.2 g of manganese (II) - acetate tetrahydrate and 415 g of liquid methylamine presented - this corresponds to a ratio of 1 part p-NTSA-Na salt to 5.5 parts of solvent. '

Preferably. Level of the resulting clear solution, an oxygen flow of 8 l / h, initiated at a stirring speed of 1800 rpm. In addition, 28.8 g of a 30% methanolic sodium methylate solution within 20 minutes at an internal temperature of -1O ⁰ C to -5 ⁰ C.

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added. The resulting reaction mixture is then stirred for an hour and 40 minutes at -10 ⁰ C while introducing oxygen (8 l / h).

The work-up is carried out as described in Example 1 with the exception that the reaction mixture is pre-treated with 8.6 g of ammonium chloride and diluted with 200 ml of methanol. This gives 61.5 g of 4,4'-dinitrostilbene-2,2'-disulfonic acid disodium salt in the form of a light yellow crystalline powder of melting point above 300 °, which has an active content (UV spectrophotometrically determined) of 92.3%. The yield of 4,4'-di-nitrostilbene-2,2'-disulfonic acid disodium salt is 74.8% of theory.

Claims (17)

- 21 - claims 1. A process for the preparation of 4,4'-dinitrostilbene-2,2 '"- disulfonic acid and salts thereof of the formula ^S SO ₃ M MO ₃ S ^/ wherein M is hydrogen, an alkali metal cation or an ammonium cation, by oxidation of 4-nitrotoluene-2-sulfonic acid or its salts with an oxidizing agent, characterized in that the oxidation in liquid, anhydrous ammonia, the alkyl derivative optionally in the presence of water and / or mixtures thereof with each other in the presence of strong bases. 2. The method according to claim 1, characterized in that the oxidation is carried out in a mixture of ammonia with water. 3. The method according to claim 1, characterized in that the base is used dissolved in a protic solvent. "ι 4. The method according to claim 3, characterized in that a low molecular weight alcohol and / or water is used as the protic solvent. 5. The method according to claim 1, characterized in that an alkali or alkaline earth compound is used as the strong base. 6. The method according to claim 5, characterized in that are used as the strong base hydroxides and alcoholates of alkali or alkaline earth metals or mixtures of such compounds, and strongly basic ion exchangers. 7. The method according to claim 1, characterized in that in addition catalysts are used. - 22 - ^M 8. The method according to claim 7, characterized in that are used as catalysts, salts, oxides or hydroxides of heavy metal compounds and / or heavy metal organic compounds. 9. The method according to claim 7, characterized in that are used as catalysts phase transfer catalysts or crown ethers. 10. The method according to claim 1, characterized in that the oxidation is carried out at temperatures between -33 ⁰ C and +50 ⁰ C. 11. The method according to claim 10, characterized in that the oxidation at temperatures between -15 ⁰ C and 3O ⁰ C is performed. 12. The method according to claim 1, characterized in that 1 to 10 parts of ammonia, alkyl derivative is optionally used in the presence of water or mixtures thereof per part of 4-nitrotoluene-2-sulfonic acid. 13. The method according to claim 12, characterized in that 3 to 6 parts of ammonia, alkyl derivative is optionally used in the presence of water or mixtures thereof per part of 4-nitrotoluene-2-sulfonic acid. 14. The method according to claim 1, characterized in that are used as oxidizing agent pure oxygen or its mixtures with inert gases or air. 15. The method according to claim 1, characterized in that 1 part of 4-kitrotoluene-2-sulfonic acid or salts suspended in the form of the moist press cake with a catalytic amount of manganese II salt in 0.5 to 3 parts aqueous ammonia solution or water and rait I to 5 parts of liquid ammonia is added so that the ammonia content of the entire reaction mixture is 60% to 80% and this mixture in the presence of oxygen as the oxidizing agent and sodium hydroxide as the base at temperatures of 0 to 25 ⁰ C and under pressure. - 23 - 16. The method according to claim 1, characterized in that the proportion of ammonia or the alkyl derivatives of ammonia in admixture with water is 50% to 99%. 17. The method according to claim 16, characterized in that the proportion of ammonia or the alkyl derivatives of ammonia in admixture with water is 60% to 80%. FO 7.1 LIN / bg *