4,4'-DIAMINO-2,2'-STILBENEDISULFONIC ACID

4,4'-Diamino-2,2'-stilbenedisulfonic acid is a symmetrical aromatic diamine commonly known as DSD acid, DAS, or amsonic acid.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contains a conjugated trans-stilbene structure, two primary amino groups, and two sulfonic acid groups.
4,4'-Diamino-2,2'-stilbenedisulfonic acid is used principally as an intermediate for fluorescent whitening agents, optical brighteners, direct dyes, reactive dyes, and other functional stilbene derivatives.

CAS Number: 81-11-8
EC Number: 201-325-2
Molecular Formula: C₁₄H₁₄N₂O₆S₂
Molecular Weight: 370.40 g/mol

SYNONYMS

4,4'-Diaminostilbene-2,2'-disulfonic Acid, 4,4'-Diamino-2,2'-stilbenedisulphonic Acid, 4,4'-Diaminostilbene-2,2'-disulphonic Acid, (E)-4,4'-Diaminostilbene-2,2'-disulfonic Acid, trans-4,4'-Diaminostilbene-2,2'-disulfonic Acid, 4,4'-Diamino-2,2'-stilbenedisulfonic Acid, DSD Acid, DSD, DAS, DASD, DASDA, Diaminostilbenedisulfonic Acid, Diamino Stilbene Disulfonic Acid, Amsonic Acid, Amsonate, Flavonic Acid, 2,2'-Stilbenedisulfonic Acid, 4,4'-diamino-, 2,2'-Disulfo-4,4'-stilbenediamine, 2,2'-Disulfo-4,4'-diaminostilbene, 4,4'-Stilbenediamine-2,2'-disulfonic Acid, 4,4'-Diaminodiphenylethylene-2,2'-disulfonic Acid, p,p'-Diaminostilbene-o,o'-disulfonic Acid, p,p'-Diaminodiphenylethylene-o,o'-disulfonic Acid, 1,2-Bis(4-amino-2-sulfophenyl)ethene, 1,2-Bis(4-amino-2-sulfophenyl)ethylene, 6,6'-(Ethene-1,2-diyl)bis(3-aminobenzenesulfonic Acid), (E)-6,6'-(Ethene-1,2-diyl)bis(3-aminobenzenesulfonic Acid), 2,2'-(1,2-Ethenediyl)bis(5-aminobenzenesulfonic Acid), 2,2'-[(E)-1,2-Ethenediyl]bis[5-aminobenzenesulfonic Acid], Benzenesulfonic Acid, 2,2'-(1,2-ethenediyl)bis[5-amino-, Benzenesulfonic Acid, 2,2'-(1E)-1,2-ethenediylbis(5-amino-, 5-Amino-2-[(E)-2-(4-amino-2-sulfophenyl)ethenyl]benzenesulfonic Acid, 5-Amino-2-[2-(4-amino-2-sulfophenyl)vinyl]benzenesulfonic Acid, 4,4'-Diamino-trans-stilbene-2,2'-disulfonic Acid, trans-Diaminostilbenedisulfonic Acid, Stilbene Diamine Disulfonic Acid, Stilbene-Based Diamine Intermediate, Stilbene Optical-Brightener Intermediate, Fluorescent-Whitening-Agent Intermediate, Optical-Brightening-Agent Intermediate, Direct-Dye Intermediate, Reactive-Dye Intermediate, Triazinyl-Stilbene Intermediate, Bis(triazinylamino)stilbene Precursor, Cellulose-Brightener Intermediate, Detergent-Brightener Intermediate, Paper-Brightener Intermediate, Textile-Brightener Intermediate, High-Purity DSD Acid, Technical-Grade DSD Acid, C₁₄H₁₄N₂O₆S₂, CAS 81-11-8, EC 201-325-2, PubChem CID 5284378, UNII 899GJ5MP05, NSC 163, MFCD00024946, REJHVSOVQBJEBF-OWOJBTEDSA-N

APPLICATIONS

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as the principal aromatic intermediate for manufacturing stilbene-based optical brightening agents.
4,4'-Diamino-2,2'-stilbenedisulfonic acid provides the conjugated stilbene chromophore responsible for ultraviolet absorption and blue fluorescence in properly substituted derivatives.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports preparation of fluorescent whitening agents that compensate for yellow coloration by emitting visible blue light.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables manufacturers to modify fluorescence, solubility, affinity, shade, and application behavior through controlled substitution of its amino groups.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a starting material for bis-triazinylaminostilbene optical brighteners.
4,4'-Diamino-2,2'-stilbenedisulfonic acid reacts with cyanuric chloride to attach reactive triazine rings to both aromatic amino groups.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports subsequent replacement of residual triazine chlorine atoms with amines, amino acids, alcohols, or other nucleophiles.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables production of extensive brightener families with different aqueous solubility, substantivity, electrolyte tolerance, and whitening performance.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as an intermediate for fluorescent whitening agents used in paper manufacturing.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives capable of adsorbing onto cellulose fibers and increasing the apparent whiteness of paper.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to brighteners applied through pulp addition, surface sizing, coating, or combinations of these methods.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables derived products to improve brightness, blue-white shade, visual cleanliness, and print contrast in paper products.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a precursor for optical brighteners used in paperboard and coated board.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives incorporated into pigment coatings containing binders, mineral pigments, and functional additives.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables brightener structures to be selected for affinity toward cellulose, starch, latex binders, or coating pigments.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to packaging board, graphical board, label stock, and coated substrates requiring a cleaner white appearance.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as an intermediate for high-affinity optical brighteners used in paper pulp.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives designed to remain associated with cellulose during sheet formation and water removal.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables adjustment of fiber affinity through the number and type of sulfonate, amino, hydroxy, or carboxylate substituents.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to improved brightener retention and reduced loss into process water when the derivative is properly selected.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as an intermediate for low- and medium-affinity brighteners used in paper-surface applications.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives that distribute through starch solutions, coating colors, or surface-treatment formulations.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables rapid optical response near the paper surface where fluorescence has a strong visual effect.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to high brightness at controlled dosage when surface compatibility and ultraviolet exposure are properly balanced.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a precursor for fluorescent whitening agents used in household laundry detergents.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives that deposit on cellulosic textiles during washing and produce a blue fluorescent effect under daylight.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables detergent brighteners to reduce the visual effect of gradual fabric yellowing.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to powder, tablet, granule, and liquid detergent systems after conversion into suitable stable derivatives.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as an intermediate for optical brighteners used in institutional and industrial laundering.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives designed to perform in alkaline wash liquors containing surfactants, builders, enzymes, and soil.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables brightener chemistry to be modified for bleach compatibility, electrolyte tolerance, and repeated-wash deposition.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to maintaining the perceived whiteness of cotton towels, sheets, uniforms, and workwear.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a precursor for optical brighteners applied to cotton fibers and fabrics.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives with affinity for cellulose through hydrogen bonding, ionic interactions, and planar aromatic association.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables whitening treatments to be incorporated into exhaust dyeing, padding, finishing, or combined laundering processes.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to brighter white yarns, woven fabrics, knitted fabrics, and finished cotton articles.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as an intermediate for whitening agents used on regenerated cellulose.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives applied to viscose, rayon, lyocell, and related cellulose-based materials.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables brightener structures to be selected according to fiber accessibility, bath pH, salt concentration, and finishing conditions.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to increased whiteness and more neutral visual shade in regenerated-cellulose textiles.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as an intermediate for fluorescent whitening agents used in textile-printing and finishing formulations.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives incorporated into padding liquors, finishing baths, pigment-print pastes, or specialty surface treatments.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables fluorescent effects to be combined with softeners, binders, resins, and compatible finishing auxiliaries.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to cleaner backgrounds and enhanced contrast in printed or lightly colored textile materials.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a key intermediate for stilbene-based direct dyes.
4,4'-Diamino-2,2'-stilbenedisulfonic acid provides two aromatic amino groups that can undergo diazotization, coupling, acylation, or triazine substitution.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports preparation of water-soluble dyes with affinity for cellulose, paper, and related substrates.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables dye shade, substantivity, leveling, fastness, and solubility to be modified through downstream molecular design.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as an intermediate for reactive dyes containing stilbene-derived chromophoric or fluorescent structures.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports attachment of triazine and other reactive groups capable of forming bonds with compatible fibers.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables preparation of multifunctional derivatives combining water solubility, fluorescence, color, and fiber reactivity.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to dye systems designed for cotton, regenerated cellulose, paper, and other hydroxyl-containing substrates.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a precursor for cationic derivatives of bis-triazinylaminostilbene optical brighteners.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports introduction of cationic substituents that modify adsorption onto negatively charged fibers or surfaces.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables derived brighteners to be tailored for cellulose materials and specialized aqueous application systems.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to molecular platforms whose ionic balance can be adjusted independently from the central fluorescent structure.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a precursor for anionic fluorescent whitening agents.
4,4'-Diamino-2,2'-stilbenedisulfonic acid provides two sulfonic acid groups that can be converted into sodium, potassium, ammonium, or organic-amine salts.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives that dissolve or disperse effectively in aqueous detergent, paper, and textile systems.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables ionic form and counterion selection to influence handling, concentration, storage stability, and application compatibility.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as an intermediate for amino-acid-substituted optical brighteners.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports attachment of glycine-, glutamate-, iminodiacetate-, taurine-, or related hydrophilic substituents through triazine chemistry.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables the resulting derivatives to combine fluorescence with improved water compatibility or altered substrate affinity.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to brightener systems developed for detergents, textiles, paper, and aqueous formulations.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as an intermediate for alkanolamine-substituted optical brighteners.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports incorporation of hydroxyalkylamino groups that can improve solubility and formulation compatibility.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables adjustment of brightener response to pH, salts, binders, surfactants, and alkaline-earth metal ions.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to concentrated liquid or solid brightener preparations after suitable derivatization and purification.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as an intermediate for optical-brightener concentrates used in paper mills.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports preparation of desalted and concentrated aqueous derivatives suitable for metered addition.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables downstream solutions to be purified through membrane separation, dialysis, electrodialysis, salting, or controlled drying.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to lower inorganic-salt content, improved storage stability, and more consistent dosing in paper processes.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a starting material for optical-brightener powders and granules.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives that can be isolated by precipitation, filtration, washing, concentration, and drying.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables downstream products to be formulated with carriers, salts, dispersants, or dust-reducing auxiliaries.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to solid products intended for detergent, textile, and paper formulations after full chemical conversion.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a raw material for fluorescent whitening agents used in soap and cleaning compositions.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives compatible with surfactants and alkaline cleaning ingredients.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables visually brighter washed surfaces or textiles when the selected derivative deposits on the intended substrate.
4,4'-Diamino-2,2'-stilbenedisulfonic acid requires the final derivative to be evaluated for chemical stability, consumer exposure, environmental release, and formulation compatibility.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as an intermediate for specialty whitening agents used in synthetic-fiber blends.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives selected for formulations containing both cellulose and compatible synthetic components.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables detergent or finishing systems to improve the visual whiteness of mixed-fiber articles.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes indirectly to balanced fluorescence when multiple fiber types respond differently to the same brightener.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a platform for producing fluorescent dyes used in analytical and materials research.
4,4'-Diamino-2,2'-stilbenedisulfonic acid provides an extended conjugated core capable of being modified with recognition, solubilizing, or reactive groups.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports preparation of water-compatible fluorescent molecules for studying adsorption, photophysics, and molecular interactions.
4,4'-Diamino-2,2'-stilbenedisulfonic acid requires each derived fluorescent compound to be characterized independently for excitation, emission, stability, and toxicity.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a molecular platform for developing fluorescent tracers and markers.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives detectable through ultraviolet illumination or fluorescence spectroscopy.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables water solubility and substrate affinity to be adjusted through sulfonate salts and amino-group substitution.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to research involving process tracing, surface marking, leakage studies, and fluorescence-based detection after suitable derivatization.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as an intermediate in the preparation of fluorescent security and identification materials.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives incorporated into compatible inks, papers, coatings, or polymer matrices.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables fluorescence to remain weak under ordinary illumination but become visible under ultraviolet light.
4,4'-Diamino-2,2'-stilbenedisulfonic acid requires the final security material to be validated for photostability, migration, printability, and resistance to extraction.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a precursor for fluorescent additives used in specialty polymer research.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatization that improves compatibility with waterborne polymers, coatings, films, or fibers.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables derived additives to modify apparent whiteness or provide ultraviolet-responsive identification.
4,4'-Diamino-2,2'-stilbenedisulfonic acid requires polymer-specific testing because ionic stilbene derivatives may differ in dispersion, migration, and thermal stability.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a precursor for optical-brightener quenchers and fluorescence-control agents.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports derivatives designed to reduce or neutralize the visible effect of anionic fluorescent whitening agents on selected substrates.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables correction of excessive fluorescence, shade imbalance, or unwanted brightener response in paper and textile processing.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to compounds whose ionic and molecular structures are tailored for interaction with existing whitening agents.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a starting material for symmetrically substituted bifunctional aromatic compounds.
4,4'-Diamino-2,2'-stilbenedisulfonic acid provides two equivalent amino groups that facilitate balanced substitution on both sides of the stilbene core.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports preparation of amides, ureas, sulfonamides, triazines, imines, and diazonium-derived compounds.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables systematic investigation of how symmetrical substitution changes fluorescence, solubility, aggregation, and substrate affinity.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as an aromatic diamine in acylation research.
4,4'-Diamino-2,2'-stilbenedisulfonic acid reacts with acid chlorides, anhydrides, activated esters, or other acylating agents under controlled conditions.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports preparation of bis-amide derivatives with modified electronic and physical properties.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables adjustment of hydrophobicity, hydrogen bonding, fluorescence, and compatibility through the selected acyl groups.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a substrate for diazotization and azo-coupling research.
4,4'-Diamino-2,2'-stilbenedisulfonic acid provides two primary aromatic amino groups capable of conversion into diazonium intermediates.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports preparation of bis-azo and related extended-conjugation dyes through controlled coupling.
4,4'-Diamino-2,2'-stilbenedisulfonic acid requires low-temperature diazotization and strict control of unstable diazonium intermediates.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as an intermediate for water-soluble direct-dye structures.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes sulfonic acid groups that promote aqueous processing after conversion into suitable salts.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports planar dye structures capable of interacting with cellulose and paper fibers.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables dye performance to be modified through additional azo, triazine, aromatic, or heterocyclic groups.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as an analytical reference material for dye- and brightener-intermediate testing.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports calibration and identity confirmation by liquid chromatography, ultraviolet spectroscopy, fluorescence analysis, and mass spectrometry.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables measurement of residual starting intermediate in optical brighteners, dyes, process solutions, and wastewater.
4,4'-Diamino-2,2'-stilbenedisulfonic acid requires accurately characterized purity, water, salt content, and isomer composition for quantitative analytical work.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a process-control analyte during optical-brightener synthesis.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports monitoring of cyanuric-chloride substitution, residual amino groups, conversion, hydrolysis, and side-product formation.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables manufacturers to correlate intermediate consumption with final brightener assay and fluorescence performance.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to quality control through chromatographic, titrimetric, spectroscopic, and colorimetric measurements.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a quality-control reference in DSD-acid production.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports measurement of residual dinitrostilbenedisulfonic acid, monoamino-mononitro intermediates, inorganic salts, and colored impurities.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables assessment of catalytic hydrogenation efficiency and product precipitation.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to consistent downstream performance when assay, hue, water, iron, and reduction completeness are controlled.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a reference substance in studies of stilbene photoisomerization.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contains an ethene linkage capable of trans–cis transformation under suitable irradiation conditions.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports investigation of how isomerization changes absorption, fluorescence, conformation, and application performance.
4,4'-Diamino-2,2'-stilbenedisulfonic acid requires protection from unnecessary intense light when isomer composition is important to downstream synthesis.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a model compound in fluorescence and ultraviolet–visible spectroscopy.
4,4'-Diamino-2,2'-stilbenedisulfonic acid provides a conjugated aromatic system whose spectra respond to pH, ionization, concentration, and aggregation.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports research on electronic transitions and substituent effects in water-soluble stilbene chemistry.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables comparison between the unsubstituted intermediate and highly fluorescent triazinyl derivatives.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a target analyte in wastewater from dye and optical-brightener production.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports monitoring of intermediate losses, incomplete reaction, equipment washing, and mother-liquor discharge.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables evaluation of adsorption, oxidation, membrane treatment, precipitation, and biological-treatment processes.
4,4'-Diamino-2,2'-stilbenedisulfonic acid requires control because its ionic form can remain mobile in aqueous industrial systems.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a reference compound in environmental-fate and bioaccumulation assessment.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports evaluation of biodegradation, sorption, phototransformation, aquatic exposure, and wastewater removal.
4,4'-Diamino-2,2'-stilbenedisulfonic acid has been assessed in Japan as not highly bioaccumulative under the cited screening framework.
4,4'-Diamino-2,2'-stilbenedisulfonic acid still requires prevention of concentrated environmental release because low bioaccumulation does not establish harmlessness.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a process-development reference for oxidative coupling of 4-nitrotoluene-2-sulfonic acid.
4,4'-Diamino-2,2'-stilbenedisulfonic acid production begins with formation of a dinitrostilbene disulfonic acid intermediate through oxidative condensation.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports evaluation of oxygen, alkaline conditions, solvent, catalyst, mixing, and by-product control in the coupling stage.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables process improvements aimed at increasing yield and reducing colored residues and wastewater burden.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as the target product during catalytic hydrogenation of dinitrostilbenedisulfonate salts.
4,4'-Diamino-2,2'-stilbenedisulfonic acid forms when both aromatic nitro groups are reduced to primary amino groups.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports continuous or batch hydrogenation processes followed by catalyst removal and acid precipitation.
4,4'-Diamino-2,2'-stilbenedisulfonic acid quality benefits from controlled temperature, hydrogen supply, catalyst activity, feed concentration, and filtration.

4,4'-Diamino-2,2'-stilbenedisulfonic acid functions as a process intermediate supplied in free-acid or salt form.
4,4'-Diamino-2,2'-stilbenedisulfonic acid can be neutralized to form more water-compatible sodium, potassium, ammonium, or amine salts.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports downstream reaction as a slurry, wet cake, salt solution, or dried powder depending on process requirements.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables handling form to be selected according to solubility, transport, storage, filtration, and reaction-equipment design.

4,4'-Diamino-2,2'-stilbenedisulfonic acid serves as a research intermediate for preparing new stilbene-based fluorescent compounds.
4,4'-Diamino-2,2'-stilbenedisulfonic acid supports combinatorial variation of triazine substituents, amino-acid residues, sulfonate groups, and aromatic side chains.
4,4'-Diamino-2,2'-stilbenedisulfonic acid enables structure–property studies relating molecular design to fluorescence intensity, hue, affinity, and environmental behavior.
4,4'-Diamino-2,2'-stilbenedisulfonic acid contributes to development of brighteners requiring lower application levels for a targeted whitening effect.

DESCRIPTION

4,4'-Diamino-2,2'-stilbenedisulfonic acid is the free-acid form of a symmetrical diaminostilbene disulfonic acid widely called DSD acid or DAS.
4,4'-Diamino-2,2'-stilbenedisulfonic acid is identified by CAS Number 81-11-8 and EC Number 201-325-2.
4,4'-Diamino-2,2'-stilbenedisulfonic acid has the molecular formula C₁₄H₁₄N₂O₆S₂ and a molecular weight of approximately 370.40 g/mol.
4,4'-Diamino-2,2'-stilbenedisulfonic acid normally corresponds to the trans or E stilbene configuration.

4,4'-Diamino-2,2'-stilbenedisulfonic acid appears as odorless yellowish microscopic needles or a cream-colored crystalline powder.
4,4'-Diamino-2,2'-stilbenedisulfonic acid forms an acidic aqueous suspension with a reported pH near 4.3 at 30 g/L.
4,4'-Diamino-2,2'-stilbenedisulfonic acid has reported water solubility below 1 mg/mL near room temperature in its free-acid form.
4,4'-Diamino-2,2'-stilbenedisulfonic acid salts, especially the disodium salt, possess substantially greater aqueous compatibility than the free acid.

4,4'-Diamino-2,2'-stilbenedisulfonic acid has a reported melting or decomposition region above approximately 325°C.
4,4'-Diamino-2,2'-stilbenedisulfonic acid is commonly produced by oxidative condensation of 4-nitrotoluene-2-sulfonic acid followed by reduction of the resulting dinitrostilbene intermediate.
4,4'-Diamino-2,2'-stilbenedisulfonic acid can be isolated through acidification, precipitation, filtration, washing, and drying after catalytic reduction.
4,4'-Diamino-2,2'-stilbenedisulfonic acid quality control commonly includes appearance, assay, water, acidity, iron, inorganic salts, color, and residual nitro intermediates.

4,4'-Diamino-2,2'-stilbenedisulfonic acid may irritate the eyes and respiratory tract, and ingestion toxicity has been reported in historical safety data.
4,4'-Diamino-2,2'-stilbenedisulfonic acid is incompatible with iron and should also be protected from strong oxidizing agents and uncontrolled reactive chemicals.
4,4'-Diamino-2,2'-stilbenedisulfonic acid may emit carbon oxides, sulfur oxides, nitrogen oxides, smoke, and irritating fumes when strongly heated or burned.
4,4'-Diamino-2,2'-stilbenedisulfonic acid should be handled with dust control, local exhaust ventilation, protective gloves, protective clothing, and eye protection.

PROPERTIES

Chemical Name: 4,4'-Diamino-2,2'-stilbenedisulfonic acid
Common Name: DSD Acid
Alternative Common Name: Amsonic Acid
Abbreviations: DSD, DAS, DASD, DASDA
Preferred IUPAC Name: 5-Amino-2-[(E)-2-(4-amino-2-sulfophenyl)ethenyl]benzenesulfonic acid
Registry Name: 2,2'-Stilbenedisulfonic acid, 4,4'-diamino-
CAS Number: 81-11-8
EC Number: 201-325-2
PubChem CID: 5284378 for the defined E-isomer
UNII: 899GJ5MP05
NSC Number: 163
MDL Number: MFCD00024946
DSSTox Identifier: DTXSID60182371 for the defined E-isomer
Molecular Formula: C₁₄H₁₄N₂O₆S₂
Molecular Weight: 370.40 g/mol
Exact Molecular Weight: Approximately 370.0297 Da
InChIKey: REJHVSOVQBJEBF-OWOJBTEDSA-N
Chemical Family: Diaminostilbene disulfonic acids
Chemical Classification: Aromatic diamine and aromatic disulfonic acid
Functional Groups: Two primary aromatic amino groups and two sulfonic acid groups
Central Structural Group: trans-Stilbene or E-ethene linkage
Amino Functionality: 2
Sulfonic Acid Functionality: 2
Physical State: Crystalline solid
Appearance: Odorless yellowish microscopic needles or cream-colored powder
Odor: Odorless
Aqueous Suspension pH: Approximately 4.3 at 30 g/L
Water Solubility of Free Acid: Less than approximately 1 mg/mL near room temperature
Water Solubility of Disodium Salt: High relative to the free acid
Melting or Decomposition Point: Greater than approximately 325°C
Boiling Point: Not applicable under ordinary conditions because decomposition is expected before boiling
Vapor Pressure: Negligible under ordinary handling conditions
Primary Airborne Exposure Form: Dust
Primary Industrial Function: Dye and optical-brightener intermediate
Primary Optical Application: Precursor for stilbene-based fluorescent whitening agents
Primary Dye Applications: Intermediate for direct dyes and reactive dyes
Primary Paper Application: Precursor for optical brighteners used in pulp, surface sizing, coatings, paper, and paperboard
Primary Textile Application: Precursor for whitening agents used on cotton, regenerated cellulose, and compatible textile blends
Primary Detergent Application: Precursor for laundry optical brighteners
Primary Derivatization Route: Reaction of amino groups with cyanuric chloride followed by nucleophilic substitution
Additional Synthetic Reactions: Diazotization, azo coupling, acylation, sulfonamide formation, urea formation, and salt formation
Common Commercial Forms: Free-acid powder, wet cake, disodium salt, or aqueous salt solution
Primary Manufacturing Intermediate: 4,4'-Dinitrostilbene-2,2'-disulfonic acid or its salts
Primary Manufacturing Route: Oxidative condensation followed by catalytic reduction
Important Starting Material: 4-Nitrotoluene-2-sulfonic acid
Important Process Impurities: Residual dinitro compound, monoamino-mononitro compound, inorganic salts, iron, colored by-products, and water
Combustibility: Probably combustible according to historical safety data
Flash Point: No reliable value available
Dust Hazard: Airborne dust may irritate the eyes and respiratory tract
Eye Hazard: May cause burning, redness, tearing, irritation, or swelling
Respiratory Hazard: Dust may cause nasal irritation, sore throat, coughing, chest discomfort, or shortness of breath
Ingestion Hazard: Toxicity by ingestion has been reported in historical reference data
Skin Hazard: Prolonged or repeated dust contact should be avoided
Chemical Stability: Stable under appropriate dry and controlled storage conditions
Important Incompatibility: Iron
Additional Incompatibilities: Strong oxidizing agents and uncontrolled reactive chemicals
Hazardous Decomposition Products: Carbon monoxide, carbon dioxide, sulfur oxides, nitrogen oxides, smoke, and irritating organic fumes
Transportation Status: No specific UN or NA number is listed for the free acid in the cited emergency database
Bioaccumulation Assessment: Determined not to be highly bioaccumulative under the cited Japanese assessment
Recommended Storage: Ambient to cool, dry, tightly closed, clean, and well-ventilated storage
Light Protection: Recommended when defined trans-isomer content and color are important
Environmental Precaution: Prevent concentrated release to drains, soil, groundwater, and surface water
Quality-Control Parameters: Appearance, assay, water, acidity, iron, ash, inorganic salts, residual nitro compounds, color, and chromatographic impurity profile
Current Data Requirement: Confirm grade-specific classification, purity, physical form, salt content, packaging, storage conditions, and shelf life from current documentation.

FIRST AID

Inhalation:
Move the affected person immediately to fresh air.
Keep the person at rest in a position comfortable for breathing.
Avoid further exposure to 4,4'-Diamino-2,2'-stilbenedisulfonic acid dust, smoke, or thermal-decomposition fumes.
Obtain medical attention if coughing, sore throat, wheezing, chest discomfort, shortness of breath, or other symptoms develop.
Provide respiratory support only through trained personnel using suitable protective equipment.

Skin Contact:
Remove contaminated clothing, footwear, watches, and accessories.
Brush away loose powder carefully without dispersing dust.
Wash the affected skin thoroughly with soap and plenty of water.
Obtain medical attention if redness, irritation, itching, burning, or discomfort develops or persists.
Wash contaminated clothing before reuse.

Eye Contact:
Rinse the eyes immediately with plenty of clean, gently flowing water.
Hold the eyelids open and move the eyes in all directions during irrigation.
Remove contact lenses when present and easy to do, then continue rinsing.
Continue irrigation for at least 20 minutes.
Obtain immediate medical attention because burning, redness, tearing, swelling, and persistent irritation may occur.

Ingestion:
Rinse the mouth carefully with water.
Do not induce vomiting.
Give one or two glasses of water only when the person is fully conscious and can swallow safely.
Never give anything by mouth to an unconscious, drowsy, or convulsing person.
Obtain immediate medical attention because toxicity by ingestion has been reported.

Note to Physicians:
No substance-specific antidote should be assumed.
Provide supportive care and treat according to the patient’s symptoms and clinical condition.
Assess the eyes, respiratory tract, gastrointestinal tract, skin, and neurological status after substantial exposure.
Consider increased susceptibility in persons with impaired pulmonary function or preexisting eye conditions.
Use current poison-center guidance and grade-specific safety documentation as the primary medical references.

HANDLING AND STORAGE

Handling:
Handle 4,4'-Diamino-2,2'-stilbenedisulfonic acid in accordance with good industrial-hygiene and aromatic-amine procedures.
Review current technical and safety documentation before opening, sampling, weighing, transferring, reacting, or drying the material.
Avoid all unnecessary contact with the skin, eyes, and clothing.
Do not breathe dust, aerosol, smoke, or thermal-decomposition fumes.
Use enclosed charging, weighing, conveying, mixing, reaction, filtration, drying, and packaging systems wherever reasonably practicable.
Avoid pouring, grinding, sweeping, or pneumatic-transfer methods that create uncontrolled airborne dust.
Use clean, dry, and chemically compatible tools and equipment.
Prevent contamination with iron, rust, strong oxidizing agents, and unfamiliar reactive substances.
Use non-iron contact materials where contamination or chemical incompatibility is possible.
Add bases, cyanuric chloride, acylating agents, diazotizing reagents, and other reactive materials gradually under controlled temperature and agitation.
Provide effective cooling and pH control during neutralization, triazine substitution, diazotization, and acid precipitation.
Wash the hands, face, and exposed skin thoroughly after handling.
Do not eat, drink, or smoke in areas where 4,4'-Diamino-2,2'-stilbenedisulfonic acid is processed.
Keep contaminated work clothing separate from personal clothing.
Keep containers tightly closed whenever the material is not being sampled or transferred.

Ventilation:
Provide effective general ventilation in storage and processing areas.
Use local exhaust ventilation at weighing stations, bag-emptying points, mixers, reactors, filters, centrifuges, dryers, mills, and packaging equipment.
Capture dust at the source rather than allowing it to spread through the workplace.
Use enclosed powder-transfer systems for frequent or large-scale operations.
Use suitable dust-collection equipment where dry material is conveyed or milled.
Prevent recirculation of contaminated air unless it has been adequately filtered.
Use particulate respiratory protection when engineering controls cannot adequately limit exposure.
Use respiratory protection suitable for acid gases and particulates when reactive processing may release acidic fumes.
Use supplied-air or self-contained respiratory equipment for fires, major releases, confined spaces, or unknown concentrations.
Select respiratory equipment through a documented occupational-exposure assessment.
Inspect and maintain ventilation, filters, ducts, enclosures, and dust collectors regularly.

Storage:
Store 4,4'-Diamino-2,2'-stilbenedisulfonic acid in tightly closed and correctly labeled containers.
Keep the material in a cool or ambient, dry, clean, secure, and well-ventilated location.
Protect 4,4'-Diamino-2,2'-stilbenedisulfonic acid from moisture, excessive heat, intense light, contamination, and physical damage.
Keep 4,4'-Diamino-2,2'-stilbenedisulfonic acid separated from iron, rust, strong oxidizing agents, and incompatible reactive chemicals.
Use container materials and liners demonstrated to be compatible with aromatic sulfonic acids and diamine intermediates.
Prevent water, dirt, metals, oxidants, acids, bases, and process residues from entering opened containers.
Reseal partially used containers immediately after sampling or transfer.
Store the free acid separately from its salts, finished dyes, optical brighteners, and waste materials.
Use first-in, first-out stock rotation within the applicable shelf life.
Inspect stored material for discoloration, caking, moisture uptake, damaged packaging, contamination, or unusual odor before use.
Maintain identity and lot segregation because isomer composition and impurity profile can affect downstream fluorescence and color.
Store analytical and high-purity grades separately from bulk technical material.

Spill and Leak Procedures:
Restrict access to the affected area and remove unnecessary personnel.
Eliminate ignition sources when this can be done safely.
Provide effective ventilation before beginning recovery operations.
Wear suitable gloves, protective clothing, eye protection, and particulate respiratory protection.
Avoid dry sweeping, compressed-air cleaning, or other methods that disperse powder.
Dampen a small solid spill carefully with water when this is compatible with the intended recovery and disposal procedure.
Collect the dampened material with suitable non-iron tools and transfer it to a compatible covered container.
Use a suitable hazardous-dust vacuum for larger dry releases when available.
Prevent 4,4'-Diamino-2,2'-stilbenedisulfonic acid from entering drains, sewers, soil, groundwater, or surface water.
Collect contaminated cleaning materials, disposable protective equipment, and residues separately.
Wash contaminated surfaces with soap and water only after bulk material has been recovered and wastewater can be contained.
Do not allow unprotected personnel to reenter until the area has been inspected and cleaned.
Dispose of recovered material through an authorized chemical-waste route.
Report significant environmental releases as required by applicable regulations.

Handling Precautions:
Wear chemical-resistant gloves selected from documented compatibility and permeation information.
Use tightly fitting chemical goggles.
Wear a face shield in addition to goggles where slurry, solution, or reaction-mixture splashing is reasonably foreseeable.
Use protective clothing and closed chemical-resistant footwear.
Provide accessible eyewash and emergency-shower equipment near major handling locations.
Use suitable particulate respiratory protection during dusty operations.
Inspect containers, liners, transfer devices, filters, ventilation systems, and dust collectors before use.
Prevent accumulation of powder on floors, ledges, equipment, structural surfaces, and ventilation ducts.
Do not use iron tools or unprotected iron equipment where incompatibility or product contamination may occur.
Control temperature, pH, reagent addition, and agitation during reduction, neutralization, triazine reaction, diazotization, coupling, and precipitation.
Prevent cross-contamination with finished optical brighteners, dyes, paper additives, detergent ingredients, food, feed, cosmetic, or pharmaceutical materials.
Use closed systems and controlled sampling to minimize worker exposure and material loss.
Verify equipment cleanliness before producing high-purity brightener or dye intermediates.
Review current technical specifications, safety documentation, occupational controls, environmental obligations, and waste procedures before production, storage, cleaning, or disposal.