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HSChapter 29
U.S. imports of 3,9-dimethyl-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide (HS 293148) totaled $16K in June 2026, traded with 1 country.
3,9-Dimethyl-2,4,8,10-Tetraoxa-3,9-Diphosphaspiro[5.5]undecane 3,9-Dioxide imports of $16K in June 2026 ran 500% above the year-to-date monthly average of $3K.
3,9-Dimethyl-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane 3,9-dioxide is a spiro-bicyclic organophosphorus compound used as a flame retardant and stabilizer intermediate in specialty polymer and coating formulations. Its spiro ring architecture distinguishes it from linear or monocyclic phosphonate esters and gives it particular utility in high-performance materials requiring thermal stability. No supplier country data is available for this heading. As with other specifically enumerated organophosphorus derivatives, importers should assess its status under CWC-related dual-use controls prior to entry.
AI-written summary of the official U.S. Census Bureau trade figures on this page — verify before relying on it.
The spiro-bicyclic architecture provides enhanced thermal and hydrolytic stability compared to open-chain phosphonate esters, making this compound attractive for use in engineering plastics, epoxy resins, and coatings where long-term performance under heat or moisture is required.
The importer should cross-reference the compound's CAS number against the current BIS Commerce Control List and the CWC Schedule 2 chemical list. If the compound or a closely related structure appears on either list, a license determination request to BIS or consultation with an export/import compliance attorney is the appropriate next step before arranging the shipment.
Monthly import values over time
Supplier Network
Get discovered by U.S. importers searching for HS 293148 — 3,9-Dimethyl-2,4,8,10-Tetraoxa-3,9-Diphosphaspiro[5.5]undecane 3,9-Dioxide. Be the first supplier listed.
HS10 import codes under this HS6 parent, each with its own page. Source: U.S. Harmonized Tariff Schedule.
| Code | Description | Import Value | Effective Tariff % | Dutiable Share | Duty Collected |
|---|---|---|---|---|---|
| 2931480000 | 3,9-DIMETHYL-2,4,8,10-TETRAOXA-3,9-DIPHOSPHASPIRO[ | $16K | 13.70% | 100.00% | $2K |
NUCLEIC ACIDS & SALTS; OTHER HETEROCYCLIC CMP, NES
HS 293499
POLYPEPTIDE PROTEIN& GLYCOPROTEIN HORMONES &DERIV
HS 293719
CMPDS CONT AN UNFUSED PYRIDINE RING ETC NESOI
HS 293339
BENZENE
HS 290220
HETEROCYCLIC COMP W NITROGEN HETERO-ATM ONLY NESOI
HS 293399
HETEROCYCLIC COMP WITH UNFUSED PYRAZOLE RING NESOI
HS 293319
| Port | Imports | Exports | Balance |
|---|---|---|---|
| HOUSTON, TX | $16K | -- | -$16K |