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C.I. Fluorescent Brightener 251

CAS 16324-27-9

Benzenesulfonic acid, 2,2'-(1,2-ethenediyl)bis[5-[[4-[(2-hydroxyethyl)amino]-6-[(3-sulfophenyl)amino]-1,3,5-triazin-2-yl]amino]-, sodium salt (1:4)

Molecular structure of 16324-27-9
4 Na⁺
US productionNot reported
Import value, 2024$44M
Top sourceIndia 28%

This chemical is listed as active in US commerce, but no company reported it to EPA’s survey for 2019 or 2023. Sites may have made or imported less than the threshold amount, or none.

Why supply is unknown

Production is reported production, not a complete census of factories. Import value and source-country shares describe a shared customs category, not a separate chemical measurement.

Where It Comes From

Customs basis: HS 320420 · basket

These shares come from HS customs code 320420, which covers 16 tracked chemicals in total. They estimate the category's origin mix, not this chemical specifically.

Source Countries
IN 28%IndiaCH 26%SwitzerlandTW 22%TaiwanDE 9%GermanyCN 8%China

Why It Matters

No EPA sector or FDA product records name a use for this chemical.

Chemical Identity

CAS16324-27-9
PubChem CIDNot recorded
DTXSIDDTXSID40889654
FormulaC36H32N12Na4O14S4
Mol. Weight1076.92 g/mol
SMILES[Na+].[Na+].[Na+].[Na+].OCCNC1=NC(NC2=CC=C(C=CC3=CC=C(NC4=NC(NC5=CC=CC(=C5)S([O-])(=O)=O)=NC(NCCO)=N4)C=C3S([O-])(=O)=O)C(=C2)S([O-])(=O)=O)=NC(NC2=CC=CC(=C2)S([O-])(=O)=O)=N1

Data Sources

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Brief citations

C.I. Fluorescent Brightener 251 (CAS 16324-27-9) https://chemicalindependence.com/chemical/16324-27-9/ EPA TSCA Inventory: CAS 16324-27-9. Retrieved 2026-10-04. https://www.epa.gov/tsca-inventory US Census international trade: HS 320420 for CAS 16324-27-9. Reporting year: 2024. https://usatrade.census.gov/