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CAS 1 record

CAS 1303-86-2

CAS 1303-86-2 matches 1 EU annex record across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 1303-86-2
CAS 1303-86-2PubChem CID 11073337

Boron oxide (B2O3)

Boron oxide appears as colorless, semi-transparent glassy lumps or hard white odorless crystals. Mp 450 °C; bp: 1860 °C. Density: 2.46 g cm-3. Moderately soluble in water. Used as an insecticide; as the starting material for the synthesis of other boron compounds; as a fluxing agent in enamels and glasses; and in mixture with 2-6% boron nitride, as a bonding agent in the hot isostatic pressing of boron nitride ceramics. — CAMEO Chemicals

IUPAC name
2,4,5-trioxa-1,3-diborabicyclo[1.1.1]pentane
Molecular formula
B2O3
Molecular weight
69.63 g/mol
Exact mass
70.0033542 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

Boron sesquioxide483W67CPF4Boron OxydatumFused boric acidCaswell No. 109BBoric oxide (B2O3)RefChem:917472Boric acid (HBO2), anhydride
16 more reported names
CHEBI:35777215-125-8259-231-2620-845-4B2O3Boric anhydrideBoric oxideBoron oxideCHEBI:30163Diboron trioxideBORON OXIDE [MI]Boron oxide (99.6%-B)Boron oxide (99.9%-B)Boron oxide, (H2O 200ppm)Boron Oxide Powder, 98% NanoBoron oxide, Puratronic, (H2O 200ppm)
Open full PubChem recordPubChem annotations3D structure image

Evidence from additional scientific databases

NIH PubChem PUG-View
Exact identifier match11073337

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

  • First Aid: Excerpt from NIOSH Pocket Guide for Boron oxide:; Eye: IRRIGATE IMMEDIATELY - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.; Skin: WATER FLUSH PROMPTLY - If this chemical contacts the skin, flush the contaminated skin with water promptly. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water promptly. If irritation persists after washing, get medical attention.; Breathing: FRESH AIR - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. Other measures are usually unnecessary.; Swallow: MEDICAL ATTENTION IMMEDIATELY - If this chemical has been swallowed, get medical attention immediately. (NIOSH, 2024) Source: CAMEO Chemicals
  • First Aid: (General first aid procedures); Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.; Skin: Water flush promptly - If this chemical contacts the skin, flush the contaminated skin with water promptly. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water promptly. If irritation persists after washing, get medical attention.; Breathing: Fresh air; Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately. Source: The National Institute for Occupational Safety and Health (NIOSH)
  • Signal: Danger Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • GHS Hazard Statements: 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, P280, P318, 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: H360 (95.1%): May damage fertility or the unborn child [Danger Reproductive toxicity]; H360FD (13.1%): May damage fertility; May damage the unborn child [Danger Reproductive toxicity] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P203, P280, P318, 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 588 reports by companies from 17 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)
  • Signal: Danger Source: NITE-CMC
  • GHS Hazard Statements: H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]; H360: May damage fertility or the unborn child [Danger Reproductive toxicity] Source: NITE-CMC
  • Precautionary Statement Codes: P203, P261, P264+P265, P271, P280, P304+P340, P305+P351+P338, P318, P319, P337+P317, P403+P233, P405, and P501 (click each P-code to see the statement) Source: NITE-CMC
  • Signal: Warning Source: NITE-CMC
  • GHS Hazard Statements: H303: May be harmful if swallowed [Warning Acute toxicity, oral]; H316: Causes mild skin irritation [Warning Skin corrosion/irritation]; H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]; H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation] Source: NITE-CMC
  • Industry Uses: Not Known or Reasonably Ascertainable; Catalyst; Flux agent; Flame retardant; Hardener; Other; Processing aids not otherwise specified Source: EPA Chemical Data Reporting (CDR)

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 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Records for CAS 1303-86-2

1 total

How CAS 1303-86-2 is used on this site

CAS 1303-86-2 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 1 EU annex record shares 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 1303-86-2 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 1303-86-2 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.

The INCI Checker accepts ingredient names, CAS numbers and EC numbers. Check this CAS number directly, then verify the result against supplier specification sheets and every linked annex condition.
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