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CAS 2 records

CAS 121-43-7

CAS 121-43-7 matches 2 EU annex records across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 121-43-7
CAS 121-43-7PubChem CID 8470

Trimethyl borate

Trimethyl borate is a member of the class of borate esters obtained by the formal condensation of three equivalents of methanol with boric acid. — ChEBI

IUPAC name
trimethyl borate
Molecular formula
C3H9BO3
Molecular weight
103.92 g/mol
Exact mass
104.0644743 Da
Topological polar surface area
27.7 Ų
Hydrogen-bond donors
0
Hydrogen-bond acceptors
3
Covalent units
1
Defined stereocentres
0

Also known as

TrimethoxyboraneMethyl boratetrimethylborateTrimethoxyboronBoric acid trimethyl esterBorester OBoric acid, trimethyl esterTrimethoxyborine
16 more reported names
Boric acid (H3BO3), trimethyl esterTrimethylester kyseliny boriteNSC-77782U64J6F5NCHEBI:38913RefChem:191751204-468-9934-685-0B(OMe)3B(OCH3)3NSC 777(MeO)3B3349-42-6Trimethyl borate-11BHSDB 5589EINECS 204-468-9
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Evidence from additional scientific databases

NIH PubChem PUG-View
Exact identifier match8470

Attributed physical-property, hazard, environmental and use annotations.

  • First Aid: Excerpt from ERG Guide 129 [Flammable Liquids (Water-Miscible / Noxious)]:; Refer to the "General First Aid" section. Specific First Aid: Wash skin with soap and water. In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove clothing if adhering to skin. (ERG, 2024) Source: CAMEO Chemicals
  • ERG2024, Guide 129 (Trimethyl borate): General First Aid:; · Call 911 or emergency medical service.; · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.; · Move victim to fresh air if it can be done safely.; · Administer oxygen if breathing is difficult.; · If victim is not breathing:; -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.; -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).; -- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.; · Remove and isolate contaminated clothing and shoes.; · For minor skin contact, avoid spreading material on unaffected skin.; · In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.; · For severe burns, immediate medical attention is required.; · Effects of exposure (inhalation, ingestion, Source: Emergency Response Guidebook (ERG)
  • Signal: Danger Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • GHS Hazard Statements: H226: Flammable liquid and vapor [Warning Flammable liquids]; H312: Harmful in contact with skin [Warning Acute toxicity, dermal]; H360FD: May damage fertility; May damage the unborn child [Danger Reproductive toxicity] Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Precautionary Statement Codes: P203, P210, P233, P240, P241, P242, P243, P280, P302+P352, P303+P361+P353, P317, P318, P321, P362+P364, P370+P378, P403+P235, P405, and P501 (click each P-code to see the statement) Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Signal: Danger Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H225 (40.5%): Highly Flammable liquid and vapor [Danger Flammable liquids]; H226 (59.5%): Flammable liquid and vapor [Warning Flammable liquids]; H301 (14.9%): Toxic if swallowed [Danger Acute toxicity, oral]; H311 (14.6%): Toxic in contact with skin [Danger Acute toxicity, dermal]; H312 (85.4%): Harmful in contact with skin [Warning Acute toxicity, dermal]; H319 (30.3%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H331 (14.6%): Toxic if inhaled [Danger Acute toxicity, inhalation]; H360 (11%): May damage fertility or the unborn child [Danger Reproductive toxicity]; H360FD (19.3%): May damage fertility; May damage the unborn child [Danger Reproductive toxicity]; H370 (19.8%): Causes damage to organs [Danger Specific target organ toxicity, single exposure] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P203, P210, P233, P240, P241, P242, P243, P260, P261, P262, P264, P264+P265, P270, P271, P280, P301+P316, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P308+P316, P316, P317, P318, P321, P330, P337+P317, P361+P364, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 383 reports by companies from 15 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.; Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H225 (100%): Highly Flammable liquid and vapor [Danger Flammable liquids]; H312 (97.4%): Harmful in contact with skin [Warning Acute toxicity, dermal]; H319 (100%): Causes serious eye irritation [Warning Serious eye damage/eye irritation] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P210, P233, P240, P241, P242, P243, P264+P265, P280, P302+P352, P303+P361+P353, P305+P351+P338, P317, P321, P337+P317, P362+P364, P370+P378, P403+P235, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 39 reports by companies from 2 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.; Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. Source: European Chemicals Agency (ECHA)
  • GHS Hazard Statements: H225 (100%): Highly Flammable liquid and vapor [Danger Flammable liquids]; H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]; H319 (100%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H360 (100%): May damage fertility or the unborn child [Danger Reproductive toxicity]; H370 (100%): Causes damage to organs [Danger Specific target organ toxicity, single exposure] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P203, P210, P233, P240, P241, P242, P243, P260, P264, P264+P265, P270, P280, P301+P317, P303+P361+P353, P305+P351+P338, P308+P316, P318, P321, P330, P337+P317, P370+P378, P403+P235, P405, and P501 (click each P-code to see the statement) Source: European Chemicals Agency (ECHA)
  • NFPA Health Rating: 1 - Materials that, under emergency conditions, can cause significant irritation. Source: Hazardous Substances Data Bank (HSDB)
  • NFPA Fire Rating: 3 - Liquids and solids that can be ignited under almost all ambient temperature conditions. Materials produce hazardous atmospheres with air under almost all ambient temperatures or, though unaffected by ambient temperatures, are readily ignited under almost all conditions. Source: Hazardous Substances Data Bank (HSDB)
  • NFPA Instability Rating: 1 - Materials that in themselves are normally stable but that can become unstable at elevated temperatures and pressures. Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Bioconcentration: Trimethyl borate is rapidly hydrolyzed to boric acid and methanol in the presence of water(1,2). Hydrolysis would be expected to be the dominate fate process for trimethyl borate in the environment(SRC). Bioconcentration is not considered an important environmental fate for trimethyl borate(SRC). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: TERRESTRIAL FATE: Trimethyl borate is rapidly hydrolyzed to boric acid and methanol in the presence of water(1,2). Hydrolysis would be expected to be the dominate fate process for trimethyl borate in the environment(SRC). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: AQUATIC FATE: Trimethyl borate is rapidly hydrolyzed to boric acid and methanol in the presence of water(1,2). Hydrolysis would be expected to be the dominate fate process for trimethyl borate in the environment(SRC). Source: Hazardous Substances Data Bank (HSDB)
  • Environmental Fate: ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), trimethyl borate, which has a vapor pressure of 136 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Trimethyl borate is rapidly hydrolyzed to boric acid and methanol in the presence of water(3,4). Hydrolysis would be expected to be the dominate fate process for trimethyl borate in the environment(SRC). Source: Hazardous Substances Data Bank (HSDB)

Mapped by: Existing checksum-valid CAS to unique PubChem CID match. Retrieved: 2026-08-31. Open source record

Scientific classifications and hazard annotations provide context and do not replace the market-specific regulatory decision shown above.

Additional source coverage and match status
SourceResultChecked
NIH PubChem PUG-ViewExact match2026-08-31

A recorded no-match is useful evidence that the source was checked; it is not a claim that the substance does not exist elsewhere.

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Records for CAS 121-43-7

2 total

How CAS 121-43-7 is used on this site

CAS 121-43-7 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 2 EU annex records share this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

Use this page when a supplier specification, SDS or raw-material dossier gives you CAS 121-43-7 and you need to see every linked Annex II–VI record in one place. The entry cards above are the quickest route to concentration limits, warnings, annex placement and product-type conditions.

Frequently asked questions

A substance identified by CAS 121-43-7 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts. For example, a substance might be restricted under Annex III with specific conditions, and the same CAS might also appear in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

Cross-reference the CAS number against your raw material specification sheets and CoA documents. When a CAS appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met in your formulation. All annex entries sharing this CAS number are listed above.

A CAS number is assigned by the Chemical Abstracts Service (USA) and is globally recognised. An EC number is a European Commission identifier from inventories such as EINECS, ELINCS or the NLP list. Both identifiers may appear in EU cosmetic annex entries. Some substances have both, some have only one, and some older entries may have neither.

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