Sulfanilic acid

I. Manufacturing Methods

1. Baking Process (Traditional Method)

• Raw Materials: Aniline + Concentrated sulfuric acid
• Process: Aniline and concentrated sulfuric acid (1:1.5~1.7 ratio) are heated at 180~220°C to produce crude sulfanilic acid
  C₆H₅NH₂ + H₂SO₄ → H₂NC₆H₄SO₃H + H₂O
• Refining: Alkali dissolution → Activated carbon decolorization → Acid precipitation → Filtration → Washing → Drying → Final product
• Advantages: Mature technology, simple operation, low capital investment
• Disadvantages: Long reaction time, high energy consumption, large wastewater discharge

2. Catalytic Process (Modern Method)

• Sulfonation of aniline with sulfuric acid under catalysis at lower temperatures (120~160°C)
• Shorter reaction time, higher yield, reduced wastewater discharge
• Representative catalysts: Lewis acids, heteropoly acids

3. Continuous Production Process

• Uses continuous reactors for automated continuous production
• Large capacity, stable quality, suitable for large-scale industrialization

II. Core Advantages

• Essential Chemical Raw Material: Indispensable intermediate in the dye industry with stable market demand
• Wide Applications: Spans dyes, pharmaceuticals, agrochemicals, and analytical reagents
• Mature Synthesis Route: The baking process has over a century of history with high technological maturity
• Low Toxicity: Rat oral LD₅₀ = 12,300 mg/kg, classified as slightly toxic
• Analytical Reference Standard: Used for determination of nitrites, aluminum, magnesium, potassium, sodium, iodine and more

III. Applications

1. Dye Industry (Core Application)

• Azo Dye Synthesis: Key intermediate in diazotization reactions for manufacturing various azo dyes
• Acid Dyes: Acid Brilliant Yellow 2G, Acid Orange II, Acid Yellow 23, Acid Yellow 17
• Direct Dyes: Direct Mixed Yellow D-3RNL, Direct Mixed Scarlet D-GLN, Direct Violet 9
• Reactive Dyes: Reactive Red K-7B, Reactive Deep Blue M-2GE, Reactive Brilliant Yellow K-6G
• Pigments: C.I. Pigment Red 56
• Optical Brighteners: VBU series

2. Pharmaceutical Industry

• Pharmaceutical intermediate for sulfonamide drug synthesis
• Important organic building block in pharmaceutical synthesis

3. Agrochemical Industry

• Fungicide for controlling wheat rust disease
• Agrochemical intermediate and adjuvant

4. Textile Printing & Dyeing Auxiliaries

• Key raw material for printing and dyeing auxiliaries
• Used to improve dyeing effect and fastness

5. Fragrances & Food Colorants

• Fragrance synthesis intermediate
• Raw material for food colorant synthesis

6. Analytical Testing

• Reference reagent — nitrite determination (used with 1-naphthylamine)
• Determination of aluminum, magnesium, potassium, sodium, iodine, iodides
• Testing for osmium and ruthenium
• Serum bilirubin determination, soil analysis
• Chromatographic analysis reagent

7. Other Applications

• Organic synthesis intermediate
• Chromatographic analysis reagent
• Building material industry additive
• Methyl orange indicator synthesis

IV. Upstream & Downstream Chain

Upstream Raw Materials

• Aniline: Primary raw material, obtained from benzene nitration and reduction
• Concentrated Sulfuric Acid: Sulfonating agent, industrial grade 98%

Downstream Products

• Sodium sulfanilate, methyl orange indicator
• Acid Orange 7, Acid Yellow 23, Acid Yellow 17
• Reactive Red series, Reactive Deep Blue series
• Direct Mixed Dye series
• Optical Brightener VBU
• C.I. Pigment Red 56
• Piperonal, 4-Chlorobenzenesulfonyl chloride
• Auramine O, Sirius Scarlet

V. Safety & Storage

• Hazard Symbol: Xi (Irritant)
• UN Number: UN 2790 8/PG 3
• HS Code: 29214210
• Storage: Cool, ventilated warehouse, away from ignition sources and heat; store separately from oxidizers, acids, and alkalis
• Health Hazard: Harmful if ingested, inhaled, or absorbed through skin; causes irritation and may cause skin sensitization
• Fire Hazard: Non-combustible; thermal decomposition releases toxic nitrogen and sulfur oxides
• Firefighting: Dry chemical, foam, sand