Azo dyes and process for the manufacture of [5-amino-2-(2-hydroxyethylamino)phenyl](2-hydroxyethyl)sulfone.

Azo dyes and process for producing [5-amino-2- (2-hydroxyethylamino) phenyl] (z-hydroxyethyl) sulfone

The invention relates to a process for the preparation of [5-amino-2- (2-hydroxyethylamino) phenyl] (2-hydroxyethyl) sulfone of the formula<chemistry id="chem0001" num="0001"><img file="EP0431389A2_D0001.tif" /></chemistry> characterized in that benzothiazoles of the formula<chemistry id="chem0002" num="0002"><img file="EP0431389A2_D0002.tif" /></chemistry> wherein E = H or CH₃, with ethylene oxide in aqueous reaction medium to N-formyl or. N`acetyl-N- (2-hydroxyethyl) aniline derivatives of the formula<chemistry id="chem0003" num="0003"><img file="EP0431389A2_D0003.tif" /></chemistry> reacted, then to the aniline derivative of the formula<chemistry id="chem0004" num="0004"><img file="EP0431389A2_D0004.tif" /></chemistry> hydrolyzed this with a diazotized amine D-NH₂ to monoazo dyes of the formula<chemistry id="chem0005" num="0005"><img file="EP0431389A2_D0005.tif" /></chemistry> kuppeit, the azo dyes (5) to azo / azoxy dyes of the formula<chemistry id="chem0006" num="0006"><img file="EP0431389A2_D0006.tif" /></chemistry> oxidized and finally this reductively cleaves to D- in a manner known per se         NH₂ and (1).

The invention also relates to the new azo or azo / azoxy dyes of the formulas (5) and (6).

D stands for the rest of a diazo component, in particular from the benzene, naphthalene or hetaryl series.

D can be substituted by conventional substituents, for example         Cl, Br, F, C₁-C₄ -Alkyl,         C₁-C₄ Alkoxy, carbalkoxy, carboxy, amino, alkylamino, dialkylamino, sulfonamido, alkylsulfonyl and in particular sulfo. Those substituents are preferred which do not undergo any change during the oxidation and reduction. The alkyl groups can have customary substituents,

Preference is given to those azo or azo / azoxy dyes of the formulas (5) and (6) in which the radical D is chosen such that after the reduction of (6) to D-         NH₂ and (1) the diazo component D-         NH₂ can be easily separated and used again in the synthesis sequence. Such residues D are, for example<chemistry id="chem0007" num="0007"><img file="EP0431389A2_D0007.tif" /></chemistry> or<chemistry id="chem0008" num="0008"><img file="EP0431389A2_D0008.tif" /></chemistry> where the benzene or naphthalene rings may have further substituents, for example         Cl, Br, C₁-C₄- Alkyl,         C₁-C₄ -Alkoxy or carboxy.

Diazo components containing sulfo groups or carboxy groups offer the advantage that the oxidation and the reduction can be carried out in an aqueous reaction medium.

Azo or azo / azoxy dyes of the formulas are particularly preferred<chemistry id="chem0009" num="0009"><img file="EP0431389A2_D0009.tif" /></chemistry> and<chemistry id="chem0010" num="0010"><img file="EP0431389A2_D0010.tif" /></chemistry> since the reduction of (8) only gives (1), (7) can be prepared by diazotizing (1) and domes on (4),

The reaction of the benzothiazoles (2) with excess ethylene oxide is preferably carried out in water at temperatures between 20 to 120 ° C, preferably between 40 to 90 ° C, and in an autoclave under 0.2 to 2.0 bar pressure. The ethylene oxide is metered in such a way that a pH of 8 to 12, preferably 9.0 to 10.5, is established. The intermediate stages are likely<chemistry id="chem0011" num="0011"><img file="EP0431389A2_D0011.tif" /></chemistry> run through, the aqueous benzothiazoles (2) are surprisingly obtained by simple ethylene oxide addition of 2- (2-hydroxyethylmercapto) -N-acyl-N- (2-hydroxyethyl) aniline of the formula (3).

The ethoxylation reaction can also be carried out in a reaction medium composed of water and a water-miscible organic solvent. Additions of emulsifiers or phase transfer catalysts can accelerate the reaction. In principle, the reaction solutions can be directly implemented.

The N-formyl or N-acetylaniline derivative of the formula (3) can be hydrolyzed both under acidic and under alkaline reaction conditions at temperatures from 80 to 120 ° C., optionally under pressure. The free aniline base of the formula (4) separates out as an oily phase at pH values ​​above 7, ie under alkaline conditions.

The coupling of (4) with diazotized amines D-NH₂ to dyes of the formula (5) takes place most advantageously at 0 to 30 ° C and a pH range of 1.0 to 5.0 in an aqueous medium. Here too, the use of emulsifiers or coupling accelerators, such as urea, can prove to be advantageous. The dyes (5) are usually obtained as crystalline compounds or can be salted out as such. Since the coupling reactions are in most cases relatively uniform, it is often possible to oxidize directly to (5) to azo / azoxy dyes of the formula (6) without intermediate isolation. The use of hydrogen peroxide in the presence of catalytic amounts of tungstates has proven to be advantageous. The oxidation takes place in an aqueous medium at 20 to 100 ° C, preferably at 40 to 80 ° C and pH values ​​from 6 to 8. The corresponding sulfoxide compounds of the formula are used as intermediates<chemistry id="chem0012" num="0012"><img file="EP0431389A2_D0012.tif" /></chemistry> go through what can be followed chromatographically. Other suitable oxidizing agents are, for example, perborates, persulfates or persulfonic acids.

The azo / azoxy dyes of the formula (6) can be isolated as yellow to red, crystalline, water-soluble compounds. Their protonation shows a clear bathochromic shift. The azo component predominates in most dyes (6); As a rule, the azoxy content is limited to 5%, as for example in (8). The azo dye (8a) can be obtained relatively uniformly by recrystallization from water or alcohol.<chemistry id="chem0013" num="0013"><img file="EP0431389A2_D0013.tif" /></chemistry>

The reduction of (6) or (8) or (8a) to (1) and D-NH₂ can be carried out by methods as described by R. Schröter in the manual for preparative methods of organic chemistry, Houben-Weyl, Volume XI, Part 1, pages 522 to 531. A reduction with sodium dithionite or glucose or a catalytic reduction with hydrogen proves to be favorable. Raney nickel, palladium-carbon or platinum compounds are primarily suitable as catalysts for this. The reductions are preferably carried out in water, water / alcohol mixtures or alcohols at 20 to 80 ° C.

In the case of (8) or (8a), a uniform solution of (1) results. (1) can be directly reacted further in this form, for example condensed with chloranil or else diazotized, or isolated as a crystalline substance by concentrating the solution.

In all other cases, the reduction results in a solution or suspension of (1) and D-         NH₂ . The latter should therefore already be chosen as the diazo component so that it can now be separated from (1) almost quantitatively. It is therefore expedient to take aromatic amino carboxylic acids or aminosulfonic acids as diazo components, such as, for example 2-amino-benzoic acid 4-amino-benzoic acid 2-amino-benzenesulfonic acid 3-amino-benzenesulfonic acid 4-amino-benzenesulfonic acid 2-amino-4-methylbenzenesulfonic acid 6-amino-2-naphthalenesulfonic acid 7-amino-1,3-naphthalenedisulfonic acid 2-amino-1,5-naphthalenedisulfonic acid 4-amino-1-naphthalenesulfonic acid 5-amino-1-naphthalenesulfonic acid and others

If the reductions are carried out in a purely aqueous medium, solutions usually result from which the benzoic acids or the aminosulfonic acids can be separated and separated as betaines by acidification and optionally salting out. (1) remains in the acidic aqueous solution and can be isolated or further reacted as already described. If one chooses aniline or α-naphthylamine as possible diazo components, after reduction the same can be separated from (1) by means of steam distillation. Other water vapor volatile aniline derivatives are also suitable as diazo components.

The compound (1) is used, for example, for the production of interesting azo dyes, such as Example 17 from DOS 3 512 340<chemistry id="chem0014" num="0014"><img file="EP0431389A2_D0014.tif" /></chemistry> or Example 5 from EP 279 351<chemistry id="chem0015" num="0015"><img file="EP0431389A2_D0015.tif" /></chemistry> and for the production of triphendioxazine dyes, such as Example 1 from EP 153 599<chemistry id="chem0016" num="0016"><img file="EP0431389A2_D0016.tif" /></chemistry> Azo dyes of the formulas (5) and (6) are used for dyeing paper, wool, synthetic polyamide fibers or leather. Clear, brilliant yellow colorations are obtained.

The formulas given for azo dyes containing sulfo groups and carboxy groups are those of the free acids. The salts are generally obtained in the preparation, in particular the alkali salts, such as sodium, potassium or lithium salts.

example 1

An emulsion of 135 g of benzothiazole and 1 g of a conventional emulsifier in 500 ml of water is heated to 60 ° C. and nitrogen is passed through for 1 hour. A total of about 300 g of ethylene oxide is then metered in over a period of about 12 hours in such a way that a pH of between 9.5 and 10.5 is maintained. The reaction is followed by thin layer chromatography. As soon as less than 1% of the initial concentration of the benzothiazole is detectable, the ethylene oxide supply is stopped and the reaction solution is heated to 80 ° C. for a further 2 hours while passing a vigorous stream of nitrogen. After the remaining ethylene oxide has been removed in this way, the approx. 800 ml reaction solution is cooled to room temperature. In addition to glycol and small amounts of polyglycols, the reaction solution contains a relatively uniform hydroxyethylaniline derivative of the formula<chemistry id="chem0017" num="0017"><img file="EP0431389A2_D0017.tif" /></chemistry> and can be implemented directly.

To characterize the product, an 80 ml sample of the solution at pH 7 is worked up extractively and by distillation. The result is a viscous, colorless oil, which due to the         1 H NMR - and IR data the above structure can be assigned.<dl id="dl0001"><dt>IR (Nujol trituration): </dt><dd>1662 cm^-¹ (CO-Schw.)</dd><dt>1 H-NMR (d₆-DMSO): δ = </dt><dd>3.05 (2H, m); 3.48 (2H, m); 3.60 (2H, m); 3.65 (2H, m); 4.68 (t,         OH ); 4.94 (t         OH ); 7.15-7.50 (m, 4H); 8.00 (s,         CHO ).</dd></dl><dl id="dl0002"><dt>Mass spectrum: m / e = </dt><dd>241 (M⁺, 45%); 213 (M⁺-CO, 45%); 182 (65%); 164 (55%); 136 (100%).</dd></dl>

Example 2

800 ml of reaction solution from Example 1 are mixed with 200 ml of 70% sulfuric acid and heated to 90-95 ° C for one hour. It is then cooled and neutralized with concentrated sodium hydroxide solution with external cooling and then adjusted to pH 12.5. A colorless oil separates out.

(However, the reaction solution from Example 1 can also be hydrolyzed alkaline by adjusting to pH 12.5-13.0 with sodium hydroxide solution and heating to 80-85 ° C. for 30 minutes) The oil is separated and as the hydroxyethylaniline of the formula<chemistry id="chem0018" num="0018"><img file="EP0431389A2_D0018.tif" /></chemistry> characterized. 1 H-NMR (d₆-DMSO): δ = 2.77 (t, 2H); 3.18 (m. 2H); 3.42 (m, 2H); 3.60 (m, 2H); 4.81 (t, 0H); 4.83 (t, OH); 5.46 (t, NH); 6.50-6.63 (m, 2H); 7.15 (m. 1H); 7.30 (m, 1H).<u style="single">Example 3</u> The emulsion of 149 g of 2-methylbenzothiazole, 1 g of a conventional emulsifier and 500 ml of water is heated to 60 ° C. in a pressure vessel and nitrogen is passed through for 1 hour. The autoclave is then closed and heated to 80 ° C. About 250 g of ethylene oxide are pressed in over a period of 3-4 hours in such a way that an internal pressure of 1.5 bar and a pH between 9.5 and 10.5 is maintained. When the total amount of ethylene oxide has been added, the mixture is heated to 80 ° C. until the pressure has dropped to 0.1 / -0.2 bar. The pressure is released and the remaining ethylene oxide is removed at 80 ° C. by passing a strong nitrogen atom through it. The approximately 750 ml reaction solution are cooled to 20 ° C. 50 ml of this colorless solution are concentrated on a rotary evaporator and the oil which remains is purified by column chromatography, ie glycol and polyglycols are separated off. A colorless viscous oil is isolated, which is spectroscopically a compound of the formula<chemistry id="chem0019" num="0019"><img file="EP0431389A2_D0019.tif" /></chemistry> is identified.<dl id="dl0003"><dt>1 H-NMR (d₆-DMSO): δ = </dt><dd>1.65 (s,         COCH₃ ); 3.04 (dt, 1H); 3.12 (t, 2H); 3.50 (dt, 2H); 3.63 (t, 2H); 4.08 (dt, 1H); 4.60 (broad, 2 OH); 7.17-7.50 (m, 4H).</dd></dl> IR (Nujol): 1640 cm^-1 (CO vibration) Acid or alkaline hydrolysis of these N-acetyl-aniline compounds provides, in analogy to Example 2, the free base 2- (2-hydroxyethylmercapto) -N- (2-hydroxyethyl) aniline.

Example 4

23.6 g of 7-amino-l, 3-naphthalenedisulfonic acid monosodium salt are stirred in 150 ml of water / 50 g of ice and 20 ml of concentrated hydrochloric acid and added dropwise at 5 to 10 ° C with 17 ml of a sodium nitrite solution (300 g / l) offset. The diazotization is complete after 1.5 hours. The small excess of nitrite is destroyed by the addition of amidosulfonic acid. The cream-colored suspension is adjusted to pH 2.5 with sodium carbonate solution. To do this, drop at approx. 10 ° C a pH 2.0 solution of 15.0 g of the free base from Example 2 in 100 ml of water. The mixture is stirred for 4 to 5 hours at 10 ° C (pH 1.5-2.0). To complete the coupling reaction, the pH is increased to 4.5 by adding sodium acetate and stirring is continued for 2 hours. 40 g of sodium chloride are added, the mixture is stirred for 1 hour and the precipitate is isolated by suction. After drying, 48 g of a salt-containing dye of the formula result<chemistry id="chem0020" num="0020"><img file="EP0431389A2_D0020.tif" /></chemistry> λmax = 454 nm (         H₂O , pH 7-8)<dl id="dl0004"><dt>1 H-NMR (d₆-DMS0): δ = </dt><dd>2.88 (t, 2H); 3.35 (t. 2H); 3.50 (t, 2H); 3.65 (m. 2H); 5.15 (broad s, 2 0H); 6.17 (t, NH); 6.85 (d. 1H); 7.83-8.07 (m, 4H); 8.16 (s, 1H); 8.30 (s, 1H); 9.30 (s, 1H).</dd></dl>

Example 5

47 g of the dye from Example 4 are stirred in 250 ml of water at pH 8-8.5, mixed with 0.2 g of sodium tungstate and heated to 70 ° C. 30 ml of an approximately 35% aqueous hydrogen peroxide solution are added dropwise. The temperature should be between 70 and 80.degree. After about 2 hours, the oxidation is checked by thin layer chromatography. The sulfoxide derivative passed through during the oxidation can also be detected. If necessary, a further 10 to 15 ml of hydrogen peroxide solution are added to oxidize the remaining sulfoxide derivative to the sulfone derivative. The mixture is then stirred at 80 ° C. for 2 hours, cooled to room temperature and to pH 0.5 to 1.0 with dilute sulfuric acid acidified. The dye is salted out with 35 g of sodium chloride and 5 g of potassium chloride and isolated. After drying, 38 g of a salt-containing dye of the formula are obtained<chemistry id="chem0021" num="0021"><img file="EP0431389A2_D0021.tif" /></chemistry> The azoxy fraction seems to be only a few percent due to DG and NMR. λmax = 406 nm (         H₂O , pH 7-8)<dl id="dl0005"><dt>1 H-NMR (d₆-DMSO): δ = </dt><dd>3.42 (t, 2H); 3.55 (t. 2H); 3.68 (t. 2H); 3.75 (t, 2H); 5.0-5.3 (broad, 2 OH); 6.9 (broad s, NH); 7.13 (d. 1H); 7.98 (dd, 1H); 8.05-8.17 (m, 2H); 8.20 (s, 1H); 8.27 (d. 1H); 8.32 (d. 1H); 9.35 (d. 1H).</dd></dl>

If the diazo component is varied in Example 4, further interesting dyes with azosulfide and azo / azoxysulfone structure can be prepared analogously to the coupling instructions (Example 4) and oxidation instructions (Example 5):<tables id="tabl0001" num="0001"><img file="EP0431389A2_D0022.tif" /></tables>

Example 16

12.5 g of 4-aminobenzenesulfonic acid are diazotized analogously to Example 4, and the resulting suspension is adjusted to pH 2.5 with sodium carbonate solution. A solution of 15.0 g of the free base from Example 2 in 100 ml of water, adjusted to pH 2.0, is added dropwise at 5 to 10 ° C. It is 5 hours at pH 1.5 to 2.5 and 10 ° C. and then stirred for 3 hours at pH 3.5 to 4.0 and 10 ° C. The pH is increased with sodium acetate solution. After coupling, the pH is adjusted to 8.0 with sodium carbonate solution. The result is a clear solution of the azo dye of the formula<chemistry id="chem0022" num="0022"><img file="EP0431389A2_D0023.tif" /></chemistry> The solution is mixed with 0.2 g of sodium tungstate and heated to 60 ° C. 35 ml of a 35% strength aqueous hydrogen peroxide solution are metered in over a period of 15 minutes, and the reaction is kept at 70 to 80.degree. The oxidation to the sulfone is complete after about 3 to 4 hours. It is cooled to 20 ° C., adjusted to pH 6.0 and salted out with 45 g of common salt. After stirring for a further 2 hours, the product is filtered off with suction and dried. 32 g of a golden yellow dye powder of the structure are obtained<chemistry id="chem0023" num="0023"><img file="EP0431389A2_D0024.tif" /></chemistry> λmax = 396 nm (         H₂O , pH 7-8)<dl id="dl0006"><dt>1 H-NMR (d₆-DMSO): δ = </dt><dd>3.38 (t, 2H); 3.50 (t, 2H); 3.60-3.75 (m, 4H); 5.0 (broad s, 2 OH); 6.94 (t, NH); 7.08 (d, 1H); 7.78 (m. 4H); 8.05 (dd, 1H); 8.17 (d. 1H).</dd></dl>

Example 17

<ul id="ul0001" list-style="none"><li>A) 35 g of the dye from Example 5 are dissolved in 150 ml of water at pH 7, mixed with 0.2 g of Raney nickel catalyst and reduced in an autoclave with 2.5 times the equimolar amount of hydrogen. The batch can warm up to 40 to 50 ° C. After the catalyst has been separated off, a clear, pale brownish solution results, from which after acidification to pH 1.0, salting out with 10 g of sodium chloride and cooling to 15 ° C., the 7-amino-1,3-naphthalenedisulfonic acid in the form of the monosodium salt can be eliminated. The desired [5-amino-2- (2-hydroxyethylamino) phenyl] (2-hydroxyethyl) sulfone of the formula remains in solution<chemistry id="chem0024" num="0024"><img file="EP0431389A2_D0025.tif" /></chemistry> The solution can now be implemented directly, for example after neutralization. For example with chloranil as described in EP 153 599. However, it can also be concentrated to dryness after neutralization on a rotary evaporator. A salt-containing product is then obtained which can be purified by recrystallization from water or alcohol and then melts at 130.degree.</li><li>B) The same product or the same solution is also obtained if 20 g of the dye from Example 16 in 100 ml of water at pH 7-8 and 50 ° C. are reacted with 15.5 g of sodium dithionite within 10 minutes The solution is decolorized, the mixture is cooled to 20 ° C. and the solution is adjusted to pH 1.5 with hydrochloric acid. After adding 20 g of sodium chloride, the mixture is stirred for about 4 to 5 hours until the 4-aminobenzenesulfonic acid is completely precipitated. After filtration, a solution of relatively uniform [5-amino-2- (2-hydroxyethylamino) phenyl] (2-hydroxyethyl) sulfone results.</li></ul>

This important intermediate is also obtained if the azo / azoxy dyes of Examples 11 to 16 are catalytically hydrogenated analogously to Example 17 A and the diazo component D- also formed         NH₂ separates as described.

Example 18

18.8 g of [5-amino-2- (2-hydroxyethylamino) phenyl] (2-hydroxyethyl) sulfone are dissolved in 150 ml of water, 50 g of ice and 25 ml of hydrochloric acid and at 0 to 3 ° C. with 17 ml of a sodium nitrite solution (300 g / l) diazotized. The diazotization is complete after 30 minutes; a solution results.

15.2 g of the free base from Example 2 are suspended in 50 ml of water and dissolved by adding 25 ml of acetic acid. This solution is added to the finished diazotization solution and the pH is increased to 3.5 to 4.0 by adding sodium acetate solution. The reaction temperature is kept at 0-5 ° C. with ice and stirred at pH 3.5 to 4.0 for 8 hours. A crystalline yellow precipitate separates, which is filtered off, washed with 50 ml of water and dried. 31.5 g of the azo dye of the formula are obtained<chemistry id="chem0025" num="0025"><img file="EP0431389A2_D0026.tif" /></chemistry> which can be recrystallized from water or alcohol and melts at l77-178 ° C. λmax = 458 nm (         H₂O , pH 7-8) <dl id="dl0007"><dt>1 H-NMR (d₆-DMSO): δ = </dt><dd>2.87 (t, 2H); 3.35 (m, 4H); 3.50 (m, 4H); 3.60-3.75 (m, 6H); 4.95 (broad 5.4 OH); 6.13 (t, NH); 6.77 (t, NH); 6.80 (d, 1H); 7.05 (d. 1H); 7.75 (dd, 1H); 7.90 (d. 1H); 7.95 (dd, 1H); 8.07 (d, 1H).</dd></dl>

Example 19

30th g of the azo dye from Example 18 are suspended in 150 ml of water, the mixture is adjusted to pH 8 and, after the addition of 0.2 g of sodium tungstate, heated to 60 ° C. (However, the coupling mixture from Example 18 can also be used directly instead of the isolated dye ). 30 ml of a 35% hydrogen peroxide solution are slowly added dropwise. The reaction is slightly exothermic. At 75 ° C a clear orange-red solution results. The mixture is stirred for one hour at 75 to 80 ° C and then cooled to room temperature. The azo dye crystallizes in golden yellow crystals. To complete the precipitation, 10 g of potassium chloride are added and the mixture is cooled to 0.degree. It is suctioned off, washed with a little water and dried at 60 ° C in a vacuum. The result is 28.2 g of azo dye of the formula<chemistry id="chem0026" num="0026"><img file="EP0431389A2_D0027.tif" /></chemistry> which can be recrystallized from water or alcohol and has a melting point of 200 ° C. λmax = 442 nm (         H₂O , pH 7-8)<dl id="dl0008"><dt>1 H-NMR (d₆-DMSO): δ = </dt><dd>3.38 (t, 4H); 3.50 (t, 4H); 3.62-3.75 (m, 8H); 4.93 (t, 2 OH); 4.97 (t, 2 OH); 6.95 (t, 2NH); 7.06 (d, 2H); 8.01 (dd, 2H); 8.12 (d. 2H).</dd></dl>

Example 20

25.8 g of the azo dye from Example 19 are suspended in 200 ml of water, 0.2 g of Raney nickel catalyst are added and the mixture is hydrogenated in an autoclave with twice the equimolar amount of hydrogen. The reaction is slightly exothermic; a temperature of 35 to 40 ° C is reached. A colorless reaction solution is obtained if the catalyst is separated off at 40 ° C. by filtration. Concentration of the solution on a rotary evaporator provides 26 g of uniform crystalline [5-amino-2- (2-hydroxyethylamino) phenyl] (2-hydroxy-ethyl) sulfone of the formula<chemistry id="chem0027" num="0027"><img file="EP0431389A2_D0028.tif" /></chemistry>

Example 21

If diazotized aniline is coupled in analogy to Example 16 in an aqueous medium onto the free base 2- (2-hydroxyethylmercapto) -N- (2-hydroxyethyl) aniline and the azo compound obtained is oxidized at 60-80 ° C. with hydrogen peroxide solution, the result is a crystalline azosulfone of the formula<chemistry id="chem0028" num="0028"><img file="EP0431389A2_D0029.tif" /></chemistry> The golden yellow compound (λ_Max = 392 nm (         H₂O , pH 7-8)) melts at 126 ° C.<dl id="dl0009"><dt>¹ H-NMR (d₆-DMSO): δ = </dt><dd>3.38 (m, 2H); 3.50 (m. 2H); 3.68 (m. 2H); 3.73 (m. 2H); 4.90 (t, OH); 4.95 (t, OH); 6.92 (t, NH); 7.08 (d, 1H); 7.45-7.58 (m, 3H); 7.80 (d. 1H); 7.86 (d. 1H); 8.04 (dd, 1H); 8.18 (d. 1H).</dd></dl>

Example 22

20 g of the azo dye from Example 21 are suspended in 200 ml of water, 0.2 g of Raney nickel catalyst are added and the mixture is hydrogenated in an autoclave with twice the equimolar amount of hydrogen. A temperature of 40 ° C. is reached after the end of the reaction, the catalyst is separated off and the aniline formed is removed completely from the solution by steam distillation. The remaining solution, which contains [5-amino-2- (2-hydroxyethylamino) phenyl] (2-hydroxyethyl) sulfone, can be used directly for further reactions, such as condensation with chloranil (see Example 17). The above reduction can also be carried out, for example, in methanol or in a methanol-water mixture.