Trimethyl phosphite

CAS 121-45-9

U.S. production volumes are classified as confidential business information.

US productionCBI

Confidential Business Information. The EPA withholds this volume because publishing it could reveal the reporting company's trade secrets.

Import value, 2024$5M

Top sourceIndia 97%

At least one company claimed its 2023 production or import volume for this chemical as confidential, so EPA withholds it.

Why supply is unknown

Production is reported production, not a complete census of factories. US production volume is confidential. Production reporting year: 2023.

Where It Comes From

Customs basis: HS 292023 · exact

EPA reports by year

2023: US production Confidential · Imports Confidential
2019: US production Confidential · Imports Confidential

Source Countries

Country of origin for US imports, from Census customs data (2024).

IN 97%IndiaCN 2%China

Japan

Domestic parents -- activity not disclosed (3)

EPA records name a US company for this chemical but do not disclose whether the company made it here or imported it.

Harcros Chemicals

Icc Industries

Si Group

EPA-registered importers (3)

Companies that report making or importing this chemical to the EPA. Registration is US-centric and does not indicate import origin.

Syensqo Sa · BE Belgium

Lanxess

Solvay

Why It Matters

Sectors

EnergyCore Chemicals

Downstream UsesNot recorded

FDA Shortage Status

Whether any manufacturer currently reports this drug as in shortage on the FDA Drug Shortages database. "Active Shortage" means at least one presentation has status "current."

No FDA shortage records

Industrial Uses

Used in 2 sectors as 3 functional roles.

•Lubricating agent in Petroleum Lubricating Oil and Grease Manufacturing (100%)Processing as a reactant
•UV stabilizer in All Other Basic Organic Chemical Manufacturing (100%)Processing—incorporation into formulation, mixture, or reaction product
•Intermediate in All Other Basic Organic Chemical Manufacturing (100%)Processing as a reactant

Chemical Identity

CAS121-45-9

PubChem CID8472

DTXSIDDTXSID4026979

FormulaC3H9O3P

Mol. Weight124.08 g/mol

SMILESCOP(OC)OC

Data Sources

EPA CompTox (DSSTox) · DTXSID4026979Retrieved 2026-04-06
PubChem · compound 8472Retrieved 2026-04-06
EPA Chemical Data ReportingReporting year: 2023 · Retrieved 2026-10-04
EPA Chemical Data ReportingReporting year: 2023 · Retrieved 2026-10-04
US Census international tradeReporting year: 2024 · Retrieved 2026-10-04

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Brief citations

Trimethyl phosphite (CAS 121-45-9) https://chemicalindependence.com/chemical/121-45-9/ EPA CompTox (DSSTox): DTXSID4026979. Retrieved 2026-04-06. https://comptox.epa.gov/dashboard/chemical/details/DTXSID4026979 PubChem: 8472. Retrieved 2026-04-06. https://pubchem.ncbi.nlm.nih.gov/compound/8472 EPA Chemical Data Reporting: 121-45-9. Reporting year: 2023. https://www.epa.gov/chemical-data-reporting EPA Chemical Data Reporting: CAS 121-45-9. Reporting year: 2023. https://www.epa.gov/chemical-data-reporting US Census international trade: HS 292023 for CAS 121-45-9. Reporting year: 2024. https://usatrade.census.gov/