Subheading 14 of 17 in heading 2931
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.
Trade Directory
List your company under HS 293148 — 3,9-Dimethyl-2,4,8,10-Tetraoxa-3,9-Diphosphaspiro[5.5]undecane 3,9-Dioxide, so the companies trading it can find you. 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 | Imports for consumption | Average duty rate | Dutiable Share |
|---|---|---|---|---|
| 2931480000 | 3,9-Dimethyl-2,4,8,10-Tetraoxa-3,9-Diphosphaspiro[ | — | -- | -- |
Imports
Imports
—YoY · free account
Low of 2 reported months · imports
Low · free accountFewer than 6 of the last 12 months reported trade, or the latest month was under $500K; the trend chart is not shown for thin series.
Through August 2026 · imports 2 of 12 months reported. Source: U.S. Census Bureau.
Imports · August 2026
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rate provision · imports
None recorded for this period.