90-20-0

Basic information

• Product Name: 1-Amino-8-hydroxynaphthalene-3,6-disulphonic acid
• Synonyms: 1-AMINO-8-NAPHTHOL-3,6-DISULFONIC ACID;4-AMINO-5-HYDROXY-2,7-NAPTHALENEDISULFONIC ACID;4-AMINO-5-HYDROXY-2,7-NAPHTHALENEDISULFONIC ACID;8-AMINO-1-NAPHTHOL-3,6-DISULFONIC ACID;1-Amino-8-naphthol-3,6-disulphonicacid;1-Naphthol-8-amino-3,6-disulfonicacid;4-amino-5-hydroxy-7-naphthalenedisulfonicacid;7-Naphthalenedisulfonicacid,4-amino-5-hydroxy-2
• CAS NO: 90-20-0
• Molecular Formula: C₁₀H₉NO₇S₂
• Molecular Weight: 319.31
• EINECS: 201-975-7
• Product Categories: Intermediates of Dyes and Pigments;OLED materials,pharm chemical,electronic
• Mol File: 90-20-0.mol
• Article Data: 8

Chemical Properties

• Melting Point: >300 °C(lit.)
• Appearance: /
• Density: 1.6832 (rough estimate)
• Refractive Index: 1.7640 (estimate)
• PKA: -0.95±0.40(Predicted)
• CAS DataBase Reference: 1-Amino-8-hydroxynaphthalene-3,6-disulphonic acid(CAS DataBase Reference)
• NIST Chemistry Reference: 1-Amino-8-hydroxynaphthalene-3,6-disulphonic acid(90-20-0)
• EPA Substance Registry System: 1-Amino-8-hydroxynaphthalene-3,6-disulphonic acid(90-20-0)

Safety Data

• Hazard Codes: Xi
• Statements: 36/37/38
• Safety Statements: 26-36
• WGK Germany: 3
• Hazardous Substances Data: 90-20-0(Hazardous Substances Data)

Usage

Uses

4-Amino-5-hydroxy-2,7-naphthalenedisulfonic Acid is useful for preparing reactive dyes.

Purification Methods

A slightly alkaline solution of Na2CO3 (ca 22g) in water (litmus) is added to a solution of 100g of the dry acid in 750mL of hot distilled water, followed by 5g of activated charcoal and 5g of Celite. The suspension is stirred for 10minutes and filtered by suction. The acid is then precipitated by adding ca 40mL of conc HCl (solution is blue to Congo Red), then filter it by suction through a shark skin filter circular sheet (or hardened filter paper) and wash it with 100mL of distilled water. The purification process is repeated. The acid is dried overnight in an oven at 60o and stored in a dark bottle The diethylamine salt has m 306-307o(dec, from aqueous EtOH). [Post & Moore Anal Chem 31 1872 1959]. [Beilstein 14 H 840, 14 I 758, 14 II 502, 14 III 2292, 14 IV 2824.]

InChI:InChI=1/C10H9NO7S2/c11-8-3-6(19(13,14)15)1-5-2-7(20(16,17)18)4-9(12)10(5)8/h1-4,12H,11H2,(H,13,14,15)(H,16,17,18)

Synthetic route

C10H8N2O6S2(2-)*2Na(1+) → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
With sulfuric acid; water at 90℃; for 5h;	65.86%

8-amino-naphthalene-1,3,6-trisulfonic acid (117-42-0) → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
With sodium hydroxide; water at 180 - 190℃; im offenen Gefaess;
With sodium hydroxide at 210℃; im geschlossenen Gefaess;
durch Alkalischmelze;
Stage #1: 8-amino-naphthalene-1,3,6-trisulfonic acid With sodium hydroxide under 6750.68 Torr; for 6h; Stage #2: With sulfuric acid In water for 2h; pH=2;

1,8-diamino-3,6-naphthalenedisulfonic acid (6362-11-4) + furan-2,3,5(4H)-trione pyridine (1:1) → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
at 200 - 210℃;

1,8-diamino-3,6-naphthalenedisulfonic acid (6362-11-4) → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
With sulfuric acid at 110 - 120℃;
With diluted alkali at 200 - 210℃; Kochen der erhaltenen Produkte nut verd. Schwefelsaeure oder Salzsaeure;

sulfuric acid (7664-93-9) + 1H-naphtho[1,8-de][1,2,3]triazine-5,8-disulfonic acid (6362-23-8) → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
at 170℃;

water (7732-18-5) + 1,1-dioxo-2H-1λ6-naphth[1,8-cd]isothiazole-4,7-disulfonic acid (408511-00-2) + sodium hydroxide → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
at 180℃; beim Schmelzen;

4-amino-5-chloro-naphthalene-2,7-disulfonic acid (784103-83-9) + potassium hydroxide → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
beim Verschmelzen;

2,7-naphthalenedisulfonic acid (92-41-1) → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
Multi-step reaction with 2 steps 1: durch Nitrierung und Reduktion der entstandenen Dinitroverbindung 2: diluted alkali / 200 - 210 °C / Kochen der erhaltenen Produkte nut verd. Schwefelsaeure oder Salzsaeure View Scheme

naphthalene (91-20-3) → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
Multi-step reaction with 4 steps 1.1: sulfuric acid / 100 - 165 °C 1.2: 10.75 h / 30 - 165 °C 2.1: nitric acid / 10 °C 3.1: iron / 60 °C 3.2: 80 - 90 °C 4.1: sodium hydroxide / 6 h / 6750.68 Torr 4.2: 2 h / pH 2 View Scheme

naphthalene-1,3,6-trisulfonic acid (86-66-8) → 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0)

Conditions	Yield
Multi-step reaction with 3 steps 1.1: nitric acid / 10 °C 2.1: iron / 60 °C 2.2: 80 - 90 °C 3.1: sodium hydroxide / 6 h / 6750.68 Torr 3.2: 2 h / pH 2 View Scheme

1-aminonaphthalene-3,6,8-trisulphonic acid trisodium salt → chromatotropic acid (148-25-4) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + C10H9NO7S2

Conditions	Yield
Stage #1: 1-aminonaphthalene-3,6,8-trisulphonic acid trisodium salt With sodium hydroxide In methanol at 180 - 200℃; under 21002.1 Torr; Stage #2: With sulfuric acid In methanol

naphthalene (91-20-3) → chromatotropic acid (148-25-4) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + C10H9NO7S2

Conditions	Yield
Multi-step reaction with 3 steps 1.1: sulfur trioxide; sulfuric acid / 65 - 150 °C 1.2: 40 °C 2.1: hydrogen / 170 °C / 150015 Torr 3.1: sodium hydroxide / methanol / 180 - 200 °C / 21002.1 Torr View Scheme

1,3,5-trichloro-2,4,6-triazine (108-77-0) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 1,4-bis((4-aminophenyl)amino)anthrancene-9,10-dione (2944-29-8) + aniline (62-53-3) → C64H42Cl2N16O16S4

Conditions	Yield
Stage #1: 1,3,5-trichloro-2,4,6-triazine; 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid With sodium carbonate In water at 0 - 5℃; for 1h; pH=4 - 5; Stage #2: aniline In water at 25 - 30℃; for 3h; pH=5 - 6; Stage #3: 1,4-bis((4-aminophenyl)amino)anthrancene-9,10-dione Further stages;	91.3%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + C12H16N2O6S2 → C22H22N4O13S4

Conditions	Yield
Stage #1: C12H16N2O6S2 With hydrogenchloride; sodium nitrite In water Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid With sodium hydrogencarbonate In water for 3h; pH=3.5;	90%

1,3,5-trichloro-2,4,6-triazine (108-77-0) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 1-amino-2-sulfonic acid-4-(3-amino-2,4,6-trimethyl-5-sulfoamidophenyl)anthraquinone monosodium salt + sodium 7-aminonaphthalene-1,3,6-trisulphonate → C46H27ClN9O24S7(7-)*7Na(1+)

Conditions	Yield
Stage #1: 1,3,5-trichloro-2,4,6-triazine; 1-amino-2-sulfonic acid-4-(3-amino-2,4,6-trimethyl-5-sulfoamidophenyl)anthraquinone monosodium salt In water at 0 - 5℃; for 4h; pH=4- 6.5; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid In water at 28 - 35℃; pH=3.5 - 4; Stage #3: sodium 7-aminonaphthalene-1,3,6-trisulphonate Further stages;	86.4%

1,3,5-trichloro-2,4,6-triazine (108-77-0) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 1-amino-2-sulfonic acid-4-(3-amino-2,4,6-trimethyl-5-sulfoamidophenyl)anthraquinone monosodium salt + sodium 3‐aminonaphthalene‐1,5‐disulfonate → C46H28ClN9O21S6(6-)*6Na(1+)

Conditions	Yield
Stage #1: 1,3,5-trichloro-2,4,6-triazine; 1-amino-2-sulfonic acid-4-(3-amino-2,4,6-trimethyl-5-sulfoamidophenyl)anthraquinone monosodium salt In water at 0 - 5℃; for 4h; pH=4- 6.5; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid In water at 28 - 35℃; pH=3.5 - 4; Stage #3: sodium 3‐aminonaphthalene‐1,5‐disulfonate Further stages;	86.4%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 10-[(4'-bromomethyl)benzil]phenothiazine (246253-72-5) → 4-hydroxy-5-(4-phenothiazin-10-ylmethyl-benzylamino)-naphthalene-2,7-disulfonic acid (246253-74-7)

Conditions	Yield
With sodium acetate In water at 5 - 25℃; for 8h; Condensation;	85%

1,3,5-trichloro-2,4,6-triazine (108-77-0) + 2-amino-1-benzenesulfonic acid (88-21-1) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 1-amino-2-sulfonic acid-4-(3-amino-2,4,6-trimethyl-5-sulfoamidophenyl)anthraquinone monosodium salt → C42H27ClN9O18S5(5-)*5Na(1+)

Conditions	Yield
Stage #1: 1,3,5-trichloro-2,4,6-triazine; 1-amino-2-sulfonic acid-4-(3-amino-2,4,6-trimethyl-5-sulfoamidophenyl)anthraquinone monosodium salt In water at 0 - 5℃; for 4h; pH=4- 6.5; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid In water at 28 - 35℃; pH=3.5 - 4; Stage #3: 2-amino-1-benzenesulfonic acid Further stages;	84.23%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + bis(2-hydroxyethyl) 2-aminoterephthalate → C22H21N3O13S2

Conditions	Yield
Stage #1: bis(2-hydroxyethyl) 2-aminoterephthalate With hydrogenchloride; cis-nitrous acid In water at 5℃; for 5h; pH=8.5; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid With sodium carbonate for 1h; pH=8.5;	83.3%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 3-{4-[(E)-2-(2,4-Dichloro-phenyl)-vinyl]-phenyl}-2-mercapto-4-oxo-3,4-dihydro-quinazoline-6-diazonium → 5-Amino-3-(3-{4-[(E)-2-(2,4-dichloro-phenyl)-vinyl]-phenyl}-2-mercapto-4-oxo-3,4-dihydro-quinazolin-6-ylazo)-4-hydroxy-naphthalene-2,7-disulfonic acid

Conditions	Yield
With sodium carbonate; sodium chloride In water 1.) 0-5 deg C, 3 h; 2.) 60 deg C, 1 h;	83%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 3-aminobenzoyl fluoride → C24H15F2N5O9S2

Conditions	Yield
Stage #1: 3-aminobenzoyl fluoride With hydrogenchloride; sodium nitrite In water at 0 - 5℃; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid With ammonium chloride In water at 0 - 5℃; for 0.666667h; pH=5.5 - 6.5;	81%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 3-aminoterephthalic acid (10312-55-7) → C18H13N3O11S2

Conditions	Yield
Stage #1: 3-aminoterephthalic acid With hydrogenchloride; cis-nitrous acid In water at 10℃; for 5h; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid With sodium carbonate pH=7.5;	80.2%

2-(p-aminophenylsulfonyl)ethyl hydrogen sulfate (2494-89-5) + 1,3,5-trichloro-2,4,6-triazine (108-77-0) + 2-amino-1-benzenesulfonic acid (88-21-1) + 1-hydroxy-6-amino-3-naphthalenesulfonic acid (87-02-5) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 2,4-Diaminobenzenesulfonic acid (88-63-1) → C43H27ClN12O23S7(6-)*6Na(1+)

Conditions	Yield
Stage #1: 1,3,5-trichloro-2,4,6-triazine; 7-amino-4-hydroxy-2-naphthalenesulfonic acid With sodium hydroxide In water at 0 - 5℃; pH=5.6 - 6.5; Stage #2: With sodium carbonate In water at 3 - 5℃; for 5h; Stage #3: 2-(p-aminophenylsulfonyl)ethyl hydrogen sulfate; 2-amino-1-benzenesulfonic acid; 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid; 2,4-Diaminobenzenesulfonic acid Further stages;	77.1%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + p-toluenesulfonyl chloride (98-59-9) → N-(p-tosyl)-H-acid (6860-97-5)

Conditions	Yield
With sodium acetate; sodium hydroxide In water at 70℃; pH=3 - 6; Darkness;	77%

1,3,5-trichloro-2,4,6-triazine (108-77-0) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 1-(4'-sulfophenyl)-3-methylpyrazol-5-one (26878-11-5) + 2-amino-4-acetylaminobenzene sulfonic acid (88-64-2) + 2-amino-1,4-benzenedisulfonic acid monosodium Salt (24605-36-5) → C35H26ClN11O20S6

Conditions	Yield
Stage #1: 1,3,5-trichloro-2,4,6-triazine; 2-amino-1,4-benzenedisulfonic acid monosodium Salt In water at 0℃; for 3h; pH=6; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid In water at 35℃; for 4h; pH=4 - 5; Stage #3: 1-(4'-sulfophenyl)-3-methylpyrazol-5-one; 2-amino-4-acetylaminobenzene sulfonic acid Further stages;	58.7%

trifluoro-[1,3,5]triazine (675-14-9) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 1-(4'-sulfophenyl)-3-methylpyrazol-5-one (26878-11-5) + 2-amino-4-acetylaminobenzene sulfonic acid (88-64-2) + 2-amino-1,4-benzenedisulfonic acid monosodium Salt (24605-36-5) → C35H26FN11O20S6

Conditions	Yield
Stage #1: trifluoro-[1,3,5]triazine; 2-amino-1,4-benzenedisulfonic acid monosodium Salt In water at 0 - 5℃; pH=3 - 4; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid In water at 25℃; pH=4 - 5; Stage #3: 1-(4'-sulfophenyl)-3-methylpyrazol-5-one; 2-amino-4-acetylaminobenzene sulfonic acid Further stages;	52.1%

C4H4ClN4(1+)*Cl(1-) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → C18H13Cl2N9O7S2(2-)*2Na(1+)

Conditions	Yield
With sodium acetate; acetic acid In water for 0.5h;	49%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 4-Dodecyl-benzenediazonium → C28H35N3O7S2(2-)*2Na(1+)

Conditions	Yield
pH 5;	44%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 4,4'-Diaminostilbene dihydrochloride → C34H22N6O14S4(4-)*4Na(1+)

Conditions	Yield
Stage #1: 4,4'-Diaminostilbene dihydrochloride diazotization; Stage #2: 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid	38.5%

4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) + 4-Dodecyl-benzenediazonium → C28H35N3O7S2(2-)*2Na(1+)

Conditions	Yield
pH 9;	38%

phosgene (75-44-5) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 2-oxo-2,3-dihydro-naphth[1,8-de][1,3]oxazine-5,8-disulfonic acid (97629-54-4)

Conditions	Yield
With alkali

8-formylquinoline (38707-70-9) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 4-[8]quinolylmethylenamino-5-hydroxy-naphthalene-2,7-disulfonic acid

Conditions	Yield
With ethanol; water

1,3,5-trichloro-2,4,6-triazine (108-77-0) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 4-(4,6-dichloro-[1,3,5]triazin-2-ylamino)-5-hydroxy-naphthalene-2,7-disulfonic acid (7538-88-7)

Conditions	Yield
With sodium hydroxide
With sodium hydroxide In water at 0 - 5℃; for 1.5h;
With sodium hydroxide; disodium hydrogenphosphate In water at 0℃; for 2h; pH=3;

6-methoxyquinolin-8-amine (90-52-8) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 4-amino-5-hydroxy-3,6-bis-(6-methoxy-[8]quinolylazo)-naphthalene-2,7-disulfonic acid

3-acetoxy-2-naphthoyl chloride (53855-64-4) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 4-hydroxy-5-(3-hydroxy-[2]naphthoylamino)-naphthalene-2,7-disulfonic acid

Conditions	Yield
With alkali Verseifung der entstandenen Acetylverbindung mit verd. Natronlauge;

2-methoxy-benzenediazonium (17356-93-3) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 5-amino-4-hydroxy-3-(2-methoxy-phenylazo)-naphthalene-2,7-disulfonic acid

Conditions	Yield
With sodium carbonate

4-methylbenzene diazonium (57573-52-1) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 5-amino-4-hydroxy-3-p-tolylazo-naphthalene-2,7-disulfonic acid (84077-76-9)

Conditions	Yield
With sodium carbonate

o-Carboxybenzenediazonium (17333-86-7) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 2-(8-amino-1-hydroxy-3,6-disulfo-[2]naphthylazo)-benzoic acid (36429-86-4)

Conditions	Yield
With sodium carbonate

diazotiertes o-Phenetidin (24892-65-7) + 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (90-20-0) → 3-(2-ethoxy-phenylazo)-5-amino-4-hydroxy-naphthalene-2,7-disulfonic acid

Conditions	Yield
With sodium carbonate

Upstream product

• 91-20-3 naphthalene 
• 86-66-8 naphthalene-1,3,6-trisulfonic acid 
• 92-41-1 2,7-naphthalenedisulfonic acid 
• 784103-83-9 4-amino-5-chloro-naphthalene-2,7-disulfonic acid 
• 90947-32-3 1,8-dinitro-3,6-naphthalenedisulfonic acid 
• 6362-11-4 1,8-diamino-3,6-naphthalenedisulfonic acid 
• 117-42-0 8-amino-naphthalene-1,3,6-trisulfonic acid 
• 7732-18-5 water 
• 408511-00-2 1,1-dioxo-2H-1λ⁶-naphth[1,8-cd]isothiazole-4,7-disulfonic acid 
• 7664-93-9 sulfuric acid 
• 6362-23-8 1H-naphtho[1,8-de][1,2,3]triazine-5,8-disulfonic acid 

Downstream Products

• 52172-47-1 1-amino-8-naphthol-7-(4-aminosulfophenyldiazinyl)-3,6-disulfonic acid 
• 61921-60-6 C₂₂H₁₂Cl₄N₁₀O₁₀S₃ 
• 58557-51-0 C₁₉H₁₄ClN₅O₁₀S₃ 
• 98978-93-9 5-(4,6-Dichloro-[1,3,5]triazin-2-ylamino)-4-hydroxy-3-(3-sulfo-phenylazo)-naphthalene-2,7-disulfonic acid 
• 25926-16-3 5-[(4,6-dichloro-1,3,5-triazin-2-yl)amino]-4-hydroxy-3-[(1-sulfo-2-naphthyl)azo]naphthalene-2,7-disulfonic acid 
• 779999-27-8 C₁₉H₁₂Cl₂N₆O₁₀S₃ 
• 17752-43-1 C₁₉H₁₂Cl₂N₆O₁₀S₃ 

Relevant articles and documents

H acid synthesis method

The invention provides a synthesis method of an H acid. By taking 1,8-naphthalic anhydride as a raw material, the H acid is obtained by sulfonation, ammoniation, Hofmann degradation and hydrolysis. The method is mild in process condition, and does not have harsh production conditions such as ultralow temperature, high temperature and high pressure; the number of production steps is small, and thenumber of equipment is small; therefore, the synthesis method is suitable for large-scale industrial production.

Method for preparing energy-efficient H-acid

The invention discloses a method for preparing energy-efficient H-acid. The method comprises the steps of conducting sulfonation on liquid naphthalene to obtain a sulfonated substance, conducting nitration on the sulfonated substance to obtain a nitrated substance, conducting denitration on the nitrated substance to obtain a denitrated substance, conducting extraction on the denitrated substance to obtain dilute sulphuric acid and an extraction mixture, conducting reextraction on the extraction mixture to obtain nitro T-acid solution, conducting reduction on the nitro T-acid solution to obtain amino T-acid solution, conducting concentration on the amino T-acid solution and caustic soda liquid to obtain concentrated amino T-acid solution and caustic soda, conducting alkali fusion and dilution on the concentrated amino T-acid solution and caustic soda to obtain a diluted alkali fusion substance, conducting separation and filtration on the diluted alkali fusion substance to obtain H-acid filter cakes, and conducting drying on the H-acid filter cakes to obtain H-acid. By the adoption of the method, continuous production of H-acid can be achieved, and economic cost is low.

Monoazo compounds having vinylsulfone type fiber reactive group and method for dyeing or printing fiber materials using the same

A monoazo compound of the following formula, STR1 wherein D is phenylene or naphthylene; X is halogeno, pyridinio or STR2 B is --OR3, --SR4, STR3 in which R3, R4, R5 and R6 are each hydrogen, alkyl, phenyl, naphthyl or benzyl, r is 0 or 1, and E is O, SO, SO2, CH2 or NR8, in which R8 is hydrogen or C1 -C4 alkyl; R, R1, R2 and R7 are each hydrogen or alkyl; A1, A2 and A3 are each phenylene, naphthylene or alkylene; Z1, Z2 and Z3 are each --SO2 CH=CH2 or --SO2 CH2 CH2 Y, in which Y is a splittable group; and p is 0 or 1; which compound is useful for dyeing or printing fiber materials to obtain a product dyed or printed in a color superior in various fastness properties with superior build-up property.