SULFANILIC ACID

Sulfanilic acid can be used for the determination of nitrite. 
Sulfanilic acid is an important intermediate of sulfonamide drugs. 
Sulfanilic acid has strong antibacterial effect on hemolytic streptococcus, meningitis and coccus, but due to poor efficacy and high toxicity, it is rarely used for oral administration. 

CAS Number: 121-57-3
Molecular Formula: C6H7NO3S
Molecular Weight: 173.19
EINECS     Number: 204-482-5

Synonyms: SULFANILIC ACID, 4-Aminobenzenesulfonic acid, 121-57-3, Sulphanilic acid, p-Aminobenzenesulfonic acid, Aniline-4-sulfonic acid, Aniline-p-sulfonic acid, Sulfanilsaeure, Aniline-p-sulphonic acid, p-Aminophenylsulfonic acid, p-Anilinesulfonic acid, Kyselina sulfanilova, p-sulfoaniline, 4-Sulfoaniline, 4-Sulfanilic acid, NSC 7170, CCRIS 4576, CHEBI:27500, HSDB 5590, EINECS 204-482-5, 1-aminobenzene-4-sulfonic acid, AI3-15414, UNII-434Z8C2635, NSC-7170, 4-aminophenylsulfonic acid, p-aminobenzene sulfonic acid, 434Z8C2635, DTXSID6024464, EC 204-482-5, SULFANILIC ACID (USP-RS), SULFANILIC ACID [USP-RS], MESALAZINE IMPURITY O (EP IMPURITY), MESALAZINE IMPURITY O [EP IMPURITY], SULFADIAZINE IMPURITY B (EP IMPURITY), SULFADIAZINE IMPURITY B [EP IMPURITY], SULFADIMIDINE IMPURITY F (EP IMPURITY), SULFADIMIDINE IMPURITY F [EP IMPURITY], SULFADIMETHOXINE IMPURITY D (EP IMPURITY), SULFADIMETHOXINE IMPURITY D [EP IMPURITY], SULFAMETHOXAZOLE IMPURITY D (EP IMPURITY), SULFAMETHOXAZOLE IMPURITY D [EP IMPURITY], 4-aminobenzene sulfonic acid, SULFADIMETHOXINE SODIUM FOR VETERINARY USE IMPURITY D (EP IMPURITY), SULFADIMETHOXINE SODIUM FOR VETERINARY USE IMPURITY D [EP IMPURITY], RefChem:6272, DTXCID604464, PARA-ANILINE SULFONIC ACID, 204-482-5, Benzenesulfonic acid, 4-amino-, 4-aminobenzene-1-sulfonic acid, MFCD00007886, CHEMBL1566888, 97675-28-0, Sulfanilsaeure [German], Kyselina sulfanilova [Czech], SUFANILIC ACID, SULFANILLIC ACID, 4-Aminobenzenesulphonic Acid (Sulphanilic Acid), P-SULFANILIC ACID, p-sulphanilic acid, 4-AMINOBENZENESULPHONIC ACID, Sulfanilic acid, 99%, Mesalazine EP Impurity O, bmse000726, Epitope ID:122241, p-aminobenzenesulphonic acid, 4-aminobenzene-sulfonic acid, SCHEMBL24407, SULFANILIC ACID [MI], 4-Amino benzenesulphonic acid, SCHEMBL157614, Sulfanilic acid, >=99.0%, Sulfadimethoxine EP Impurity D, SULFANILIC ACID [HSDB], SCHEMBL3290419, SCHEMBL3914014, SCHEMBL6630970, SCHEMBL7068968, Sulfanilic acid, 98%, tech., NSC7170, BB_SC-07049, Nitrate Reagent B, for microbiology, BBL011603, BDBM50443531, EBC-03233, MSK159314, SBB028140, STK661383, Sulfanilic acid, ACS reagent, 99%, AKOS000118732, NCGC00090886-01, NCGC00090886-02, AC-12565, FA139881, VS-02984, Sulfanilic Acid [for Biochemical Research], ST4084010, Sulfanilic acid, p.a., 98.0-102.0%, NS00000298, S0120, U0107, EN300-19269, C06335, E80415, Sulfanilic acid, Vetec(TM) reagent grade, 99%, USP Solution Sulfanilic Acid TS Conforms to USP, Q253746, Sulfanilic acid, puriss. p.a., >=99.0% (T), 4-Aminobenzenesulfonic acid 100 microg/mL in Methanol, Sulfanilic acid, JIS special grade, 99.0-100.5%, F0001-0346, Z104473374, Sulfanilic acid, United States Pharmacopeia (USP) Reference Standard, Sulfanilic acid, 99.0-100.5%, suitable for determination of nitroxide, Benzenesulfonic acid,4-amino-,diazotized,coupled with dyer’s mulberry extract, InChI=1/C6H7NO3S/c7-5-1-3-6(4-2-5)11(8,9)10/h1-4H,7H2,(H,8,9,10, Sulfanilic Acid, Pharmaceutical Secondary Standard; Certified Reference Material, 129674-17-5, Benzenesulfonic acid,4-amino-,diazotized,coupled with 5,5'-oxybis[1,3-benzenediol],sodium salt, Mesalazine EP Impurity O; Sulfamethoxazole EP Impurity D; Sulfadiazine EP Impurity B; Sulfadimethoxine EP Impurity D; Sulfadimidine EP Impurity F, 4-aminobenzenesulfonate;SULFANILIC ACID, ANHYDROUS, REAGENT (ACS)SULFANILIC ACID, ANHYDROUS, REAGENT (ACS)SULFANILIC ACID, ANHYDROUS, REAGENT (ACS)SULFANILIC ACID, ANHYDROUS, REAGENT (ACS);Diazobenzenesulfonic acid test solution(ChP);SULFANILIC ACID ANHYD PWD;Sulfanilic acid puriss. p.a., >=99.0% (T);Sulfanilic acid Vetec(TM) reagent grade, 99%;BES SODIUM SALT HIGH PURITY GRADE;p-Anilinesulfonic acid anhydrous

Sulfanilic acid is also rarely used. 
It is used as an intermediate for the synthesis of other sulfonamides, and is also used as a raw material for the synthesis of agricultural "Huangcaoling" abroad. 
Sulfanilic acid can also be used as an analytical reagent, such as a reagent for the photometric determination of nitrite and sodium nitroferricyanide. 

For biochemical research, organic synthesis and pharmaceutical industry. 
Sulfanilic acid is the main raw material for synthesizing sulfonamides. 
In addition to preparing crystalline sulfonamides for external anti-inflammatory, it can also synthesize other sulfonamides such as sulfamidine, sulfamethoxazine, and sulfamethazine.

Sulfanilic acid is an off-white, zwitterionic crystalline solid used primarily as a building block for azo dyes, pharmaceuticals, and pesticides. 
Sulfanilic acid is produced by the sulfonation of aniline using sulfuric acid. 
It is highly soluble in alkali but insoluble in mineral acids, with a melting point of.

Sulfanilic acid is an organic compound with the formula H3NC6H4SO3. 
It is an off-white solid. 
Sulfanilic acid is a zwitterion, which explains its high melting point compared to the related compounds aniline and benzenesulfonic acid.

Sulfanilic acid is a common building block in organic chemistry.
Sulfanilic acid is an aromatic organic compound containing both amino and sulfonic acid functional groups, widely used as a chemical intermediate in dye manufacturing and analytical chemistry.
Its molecular formula is C₆H₇NO₃S.

Sulfanilic acid is also known as p-aminobenzenesulfonic acid.
Chemically, sulfanilic acid consists of a benzene ring substituted with an amino group (–NH₂) and a sulfonic acid group (–SO₃H) in the para position.
This structure gives the molecule both acidic and basic properties.

In solid form it often exists as a zwitterion.
Physically, sulfanilic acid appears as a white to gray crystalline powder.
It is odorless and relatively stable under normal conditions.

Sulfanilic acid has limited solubility in cold water but dissolves more readily in hot water or alkaline solutions.
Sulfanilic acid exhibits both acidic and basic behavior because of its functional groups.
The sulfonic acid group contributes strong acidity.

The amino group provides nucleophilic and basic character.
The compound is chemically stable under normal storage conditions.
It does not readily decompose at room temperature.

Sulfanilic acid should be stored in a cool, dry environment.
Sulfanilic acid is a key intermediate in azo dye synthesis.
It undergoes diazotization to form diazonium salts.

These salts are then coupled with aromatic compounds to produce colored dyes.
In analytical chemistry, sulfanilic acid is used in colorimetric reactions, particularly in nitrite determination.
Sulfanilic acid reacts with nitrite under acidic conditions to form diazonium compounds.

This reaction is the basis of several analytical methods.
Sulfanilic acid also participates in pharmaceutical and chemical manufacturing as an intermediate.
Its reactive functional groups allow further chemical transformations.

This supports a variety of industrial synthesis processes.
Sulfanilic acid is best described as an aromatic sulfonic acid compound used primarily as an intermediate in dye production and analytical chemistry.

Sulfanilic acid is classified as an aromatic sulfonic acid derivative, a group of compounds widely used in industrial organic chemistry.
Its structure combines an aromatic ring with strongly polar functional groups.
This combination gives it both chemical stability and reactivity.

The molecule exhibits high polarity because of the sulfonic acid group.
This contributes to strong intermolecular interactions in the solid state.
As a result, sulfanilic acid has a relatively high melting point compared with many aromatic compounds.

Sulfanilic acid participates readily in coupling reactions with aromatic compounds.
After diazotization, the resulting diazonium salt can react with phenols or aromatic amines.
These reactions produce intensely colored azo compounds.

Because of the sulfonic acid group, sulfanilic acid derivatives often have improved water solubility compared with many aromatic compounds.
This property is useful in dye chemistry and analytical reagents.
Water solubility helps dyes bind to fibers and disperse in aqueous systems.

The compound may also act as a buffering or acidic component in certain chemical systems.
Its sulfonic acid functionality allows it to donate protons in solution.
This contributes to controlled reaction conditions in some processes.

Melting point: >300 °C (lit.)
Boiling point: 288 °C
Bulk density: 620 kg/m³
Density: 1.485 g/cm³
Vapor pressure: 0 Pa at 25 °C
Refractive index: 1.5500 (estimate)
Storage temperature: Store below +30 °C
Solubility: 10 g/L
pKa: 3.24 (at 25 °C)
Form: Solid
Color: White to off-white
pH: 2.5 (10 g/L, H₂O, 20 °C)
Water solubility: 0.1 g/100 mL (20 °C)
Merck: 14,8926
BRN: 908765
Stability: Stable; incompatible with strong oxidizing agents
InChI: 1S/C6H7NO3S/c7-5-1-3-6(4-2-5)11(8,9)10/h1-4H,7H2,(H,8,9,10)
InChIKey: HVBSAKJJOYLTQU-UHFFFAOYSA-N
SMILES: Nc1ccc(cc1)S(O)(=O)=O
LogP: −2.3 at 25 °C

Sulfanilic acid has a zwitterionic structure in the solid state, meaning the amino group is protonated while the sulfonic acid group is deprotonated.
This internal ionic form contributes to its relatively low solubility in cold water.
It also influences its crystalline structure and stability.

Sulfanilic acid exhibits strong acidity due to the sulfonic acid group, which is one of the strongest organic acid functional groups.
This group remains largely ionized in aqueous solution.
The amino group, however, can participate in nucleophilic reactions.

Sulfanilic acid plays an important role in diazotization reactions.
When treated with nitrous acid under acidic conditions, it forms a diazonium salt.
This intermediate is essential in the synthesis of azo dyes.

The aromatic ring of sulfanilic acid allows electrophilic and nucleophilic substitution reactions.
These reactions enable the formation of various substituted aromatic compounds.
This versatility supports its use as a synthetic intermediate.

Sulfanilic acid is often used in analytical chemistry reagents, particularly in colorimetric assays.
Sulfanilic acid participates in reactions that produce colored azo compounds.
These reactions are useful for detecting nitrite and related species.

The compound is thermally stable under moderate conditions.
However, strong heating may lead to decomposition.
Proper storage away from excessive heat helps maintain stability.

Sulfanilic acid is also known for good chemical compatibility with many reagents used in dye and pharmaceutical synthesis.
Its functional groups allow controlled chemical modification.
This flexibility makes it useful in industrial chemistry.

Because of its sulfonic acid group, sulfanilic acid is often highly water-soluble in alkaline solutions, forming sulfonate salts.
These salts may show improved solubility and reactivity.
This property is often used in industrial processing.

Sulfanilic acid is a chemically stable aromatic compound with both acidic and nucleophilic properties, making it valuable in dye chemistry, analytical reactions, and chemical synthesis.
Sulfanilic acid can form salts with metal ions and organic bases.
These salts may have different solubility or reactivity characteristics.

This property is useful in chemical synthesis and formulation chemistry.
In laboratory chemistry, sulfanilic acid is often used to prepare analytical reagents for colorimetric detection methods.
These reagents form colored products in the presence of specific analytes.

Such reactions are widely used in environmental and water analysis.
Because of its stable aromatic structure and reactive functional groups, sulfanilic acid serves as an important building block for synthesizing complex organic molecules.

Sulfanilic acid is used to produce dyes, pigments, and specialty chemicals.
This versatility makes it valuable in industrial chemistry.

Uses Of Sulfanilic acid:
Sulfanilic Acid (Sulfadimethoxine EP Impurity D) is a toxic metabolite of Tartrazine (T007700). Used as Ehrlich’s reagent, for detecting of nitrites. Antibacterial.
Sulfanilic acid may be used for the functionalization of single-walled carbon nanotubes (SWNTs) with aryl sulfonate groups.

As the compound readily form diazo compounds, it is used to make dyes and sulpha drugs. 
This property is also used for the quantitative analysis of nitrate and nitrite ions by diazonium coupling reaction with N-(1-Naphthyl) ethylene diamine, resulting in an azo dye, and the concentration of nitrate or nitrite ions were deduced from the color intensity of the resulting red solution by colorimetry.
Sulfanilic acid is also used as a standard in combustion analysis.

Sulfanilic acid is widely used as an intermediate in the production of azo dyes.
It undergoes diazotization followed by coupling reactions to form colored compounds.
These dyes are used in textiles, inks, and pigments.

In analytical chemistry, sulfanilic acid is used in colorimetric methods for detecting nitrite ions.
Sulfanilic acid reacts with nitrite to form a diazonium compound that produces a colored azo dye.
This reaction is widely used in water quality testing and environmental analysis.

Sulfanilic acid is used in the manufacture of optical brighteners and fluorescent whitening agents.
These compounds enhance the brightness of textiles, paper, and detergents.
They help materials appear whiter and more vivid.

In pharmaceutical synthesis, sulfanilic acid serves as an intermediate for producing certain medicinal compounds.
Its amino and sulfonic acid groups allow further chemical modification.
This supports the synthesis of specialized organic molecules.

Sulfanilic acid is used in pigment and printing ink production.
It contributes to the formation of stable colored compounds.
These pigments are used in coatings, inks, and plastics.

In laboratory reagents, sulfanilic acid is used as a component in chemical test kits.
It participates in reactions that produce colored indicators.
These tests are useful for analytical and diagnostic applications.

Sulfanilic acid is applied in water treatment analysis to monitor nitrite and nitrate levels.
The color-forming reaction allows accurate measurement.
This is important for environmental monitoring.

In chemical manufacturing, sulfanilic acid acts as a building block for various sulfonated aromatic compounds.
These compounds are used in dyes, detergents, and specialty chemicals.
Its functional groups enable many synthetic transformations.

Sulfanilic acid is used wherever azo dye synthesis, analytical color reactions, and sulfonated aromatic intermediates are required in industrial and laboratory chemistry.
Sulfanilic acid is used in the production of food and environmental testing reagents, especially for detecting nitrites in water and food samples.

Sulfanilic acid forms colored azo compounds that allow visual or spectrophotometric measurement.
This makes it important in quality control laboratories.

In textile dye manufacturing, sulfanilic acid serves as a precursor for dyes that bind strongly to fibers.
Its sulfonic acid group improves water solubility and dye affinity.
This supports efficient textile coloring processes.

Sulfanilic acid is used in the synthesis of acid dyes and direct dyes.
These dyes are commonly applied to materials such as wool, silk, leather, and paper.
They provide strong and stable coloration.

In photographic and imaging chemistry, sulfanilic acid derivatives may be used in specialized color-forming reactions.
These reactions help produce stable pigments or reactive intermediates.
Such uses are specialized but well established.

Sulfanilic acid is also used in corrosion inhibitor formulations and specialty chemical blends.
Its sulfonic acid group can interact with metal surfaces.
This may help improve protective coatings or treatments.

In electrochemical and analytical research, sulfanilic acid derivatives are used as reagents or intermediates.
They help generate colored or reactive compounds used for detection.
This supports analytical method development.

Sulfanilic acid is applied in the production of specialty intermediates for agrochemicals and industrial chemicals.
Its aromatic and functional groups allow further chemical modification.
This supports synthesis of complex organic compounds.

In laboratory teaching and research, sulfanilic acid is commonly used in experiments involving diazotization and azo coupling reactions.
These reactions demonstrate important principles of aromatic chemistry.

They are frequently used in organic chemistry education.
Sulfanilic acid is used wherever aromatic sulfonic intermediates, azo dye chemistry, and analytical color reactions are required in industrial production, laboratory research, and environmental analysis.

Safety Profile Of Sulfanilic acid:
Sulfanilic acid presents moderate chemical hazards and should be handled with appropriate safety precautions in laboratory and industrial environments.
Although relatively stable, exposure to dust or concentrated material can cause irritation.
Standard protective measures are recommended.

Skin contact may cause mild to moderate irritation.
Sulfanilic acid symptoms may include redness or dryness after prolonged exposure.
Protective gloves should be worn during handling.

Eye contact may result in irritation and discomfort.
Dust particles can cause redness, tearing, or burning sensation.
Eyes should be rinsed thoroughly with water if exposure occurs.

Inhalation of dust may cause respiratory tract irritation.
Symptoms can include coughing, throat irritation, or breathing discomfort.
Adequate ventilation and dust control should be used in workplaces.

Ingestion may cause gastrointestinal irritation.
Symptoms can include nausea, stomach discomfort, or vomiting.
Medical attention should be sought if significant ingestion occurs.

Sulfanilic acid is not highly flammable, but dust may burn if exposed to strong heat or flame.
Thermal decomposition can produce toxic fumes such as nitrogen oxides and sulfur oxides.
Appropriate fire safety precautions should be followed.

The compound is chemically stable under normal storage conditions.
It should be stored in tightly closed containers in a cool, dry place.
Sulfanilic acid should be kept away from strong oxidizing agents.