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Optical Brightener CXT (C.I. 71)
CAS: 27344-41-8
SKU: S2267
Optical Brightener CXT (C.I. 71) | SKU: S2267
Synonyms: Disodium 4,4′-bis(2-sulfostyryl)biphenyl; Disodium distyrylbiphenyl disulfonate; Fluorescent Brightener 351; Fluorescent Brightener CBS-X; Optical Brightener CBS-X; Disodium 4,4′-bis(2-sulfonatostyryl)biphenyl
Optical Brightener CXT (C.I. 71)
Optical brightener CXT is the disodium salt of 4,4′-bis(2-sulfostyryl)biphenyl, also called disodium distyrylbiphenyl disulfonate, with the formula C28H20Na2O6S2 and a molecular weight of 562.57 g/mol. In the trade the same chemistry is sold as fluorescent brightener 351 or as the CBS-X type. It is a yellow crystalline powder that melts above 300 °C and is typically supplied at about 97% purity. Fluorescent whitening agents of this kind work by absorbing invisible near-UV light and re-emitting it as visible blue light. The blue emission offsets the yellow cast of cotton and other cellulosic fabrics, so washed goods look whiter and brighter than the dye-free fibre alone could achieve. Because the two sulfonate groups make the molecule water-soluble, it can be incorporated into laundry powders, liquid detergents, detergent bars, fabric softeners and industrial cleaners. Typical use levels are a small fraction of a percent by weight. Sarchem Labs offers optical brightener CXT (SKU S2267) for formulators, textile and detergent laboratories and chemical distributors. Each lot ships with a Certificate of Analysis and Safety Data Sheet, and laboratory to bulk quantities can be quoted on request.
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Specifications

Melting Point>300°C
ColorYellow
Formula Weight562.56
Physical FormCrystal-Powder at 20°C
Chemical Name or MaterialDisodium 4,4′-bis(2-sulfostyryl)biphenyl
Molecular Weight562.57 g/mol
SMILES StringC1=CC=C(C(=C1)C=CC2=CC=C(C=C2)C3=CC=C(C=C3)C=CC4=CC=CC=C4S(=O)(=O)[O-])S(=O)(=O)[O-].[Na+].[Na+]
CAS Number27344-41-8
Storage TemperatureRoom temperature
Empirical FormulaC28H20Na2O6S2
MDL NumberMFCD00318874
InChI1S/C28H22O6S2.2Na/c29-35(30,31)27-7-3-1-5-25(27)19-13-21-9-15-23(16-10-21)24-17-11-22(12-18-24)14-20-26-6-2-4-8-28(26)36(32,33)34;;/h1-20H,(H,29,30,31)(H,32,33,34);;/q;2*+1/p-2/b19-13+,20-14+;;
InChI KeyPMPJQLCPEQFEJW-HPKCLRQXSA-L
PubChem CID5332133
FormSolid (yellow crystal-powder)
Purity97%
ApplicationsLaundry detergents: the main application of distyrylbiphenyl brighteners; used in compact and conventional powders, liquid detergents, detergent bars and fabric softeners to improve the whiteness of cotton and other cellulosic fabrics.

Applications

Laundry detergents: the main application of distyrylbiphenyl brighteners; used in compact and conventional powders, liquid detergents, detergent bars and fabric softeners to improve the whiteness of cotton and other cellulosic fabrics.
Industrial and institutional cleaners: incorporated in industrial laundry products where shade consistency and a brilliant white appearance are required over a range of washing temperatures.
Textile whitening trials: evaluated on cellulosic fibres for exhaustion, whiteness gain and light fastness in dyehouse laboratories.
Formulation and quality-control research: a reference fluorescent whitening agent for comparing brighteners, setting dosage and testing compatibility with surfactants, enzymes and bleach systems.
Fluorescence and photophysics studies: a stilbene-biphenyl chromophore for UV-excitation and blue-emission studies in aqueous media.

Product Description

What is Optical Brightener CXT?

Optical brightener CXT is a distyrylbiphenyl disulfonate: a biphenyl core carrying two styryl arms, each arm bearing an ortho sulfonate group, as the disodium salt. The formula is C28H20Na2O6S2 and the molecular weight is 562.57 g/mol. The extended conjugated system absorbs in the near-ultraviolet and emits in the blue region, and the sulfonate groups provide the water solubility and substantivity needed for use in aqueous wash liquors.

The commercial material is the trans,trans (E,E) isomer, which is the fluorescent form; strong UV light can isomerise the double bonds of stilbene-type brighteners to non-fluorescent cis forms, so keep the powder and its solutions away from strong light.

Uses of Optical Brightener CXT

By volume, the main use of this chemistry is in household and industrial laundry products. Distyrylbiphenyl brighteners are valued in detergents because they perform well on cotton from cold to medium wash temperatures, tolerate typical surfactant systems and give a clean, neutral-blue white. They are used in powders, liquids, detergent bars, fabric softeners and soaps, normally at a fraction of a percent of the formulation.

For textile and formulation laboratories, a CBS-X-type brightener is also a benchmark for evaluating new brighteners, optimising the dosage that maximises whiteness without a visible green or blue overshoot, and checking compatibility with enzymes, bleaches and builders.

Buying and Handling Considerations

The grade offered is about 97% purity. Ask for the Certificate of Analysis of the shipped lot and, if relevant to your process, for the E,E-isomer content, the assay by HPLC or UV and the insoluble matter, because these influence strength and dissolution in a wash liquor. For powder detergents, tell us if particle size or bulk density matters. Store in a tightly closed container at room temperature, away from moisture, strong light and strong oxidisers.

Safety Information

  • Pictogram / Signal Word: GHS07 (exclamation mark) | Warning
  • Hazard Statements: H315 (causes skin irritation), H319 (causes serious eye irritation)
  • Hazard Classification: Skin Irrit. 2, Eye Irrit. 2, as derived from the listed hazard statements
  • Precautionary Statements: P261, P264, P270, P271, P280, P302 + P352, P304 + P340, P305 + P351 + P338, P330, P362 + P364, P403 + P233, P405, P501
  • Storage: Room temperature, tightly closed, in a well-ventilated place; keep locked up
  • PPE: Eye protection, gloves and, where dust is generated, a particulate respirator

Avoid breathing dust, avoid contact with skin and eyes, and dispose of the material in accordance with local regulations.

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No related products found.

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FAQs: Optical Brightener CXT (C.I. 71)

It is used as a fluorescent whitening agent, mainly in laundry powders, liquid detergents, detergent bars and fabric softeners, where it absorbs near-UV light and emits blue light so that cotton and other cellulosic fabrics look whiter.

Chemically, yes: the compound is disodium 4,4′-bis(2-sulfostyryl)biphenyl, CAS 27344-41-8, which is sold as CBS-X, fluorescent brightener 351 and disodium distyrylbiphenyl disulfonate. Check the CAS number rather than the trade name when comparing suppliers.

The formula is C28H20Na2O6S2, the molecular weight is 562.57 g/mol and the melting point is above 300 °C. The purity is 97%.

Use levels are normally a small fraction of a percent of the finished product by weight. The best dosage depends on the formulation and the fabric, so determine it in trials.

It is listed as a skin irritant (H315) and a serious eye irritant (H319), with the signal word Warning. Avoid dust, wear gloves and eye protection and follow the Safety Data Sheet.

Keep it tightly closed at room temperature, dry and protected from strong light.

Yes. A Certificate of Analysis and Safety Data Sheet accompany every lot of SKU S2267, and bulk quantities can be quoted on request.