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Annex II Entry 1678 03/11/2021

Hymexazol (ISO); 3-hydroxy-5-methylisoxazole

Hymexazol (ISO); 3-hydroxy-5-methylisoxazole is listed in Annex II as a prohibited substance for cosmetic products placed on the EU market.

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Prohibited substance— Annex II, EU Regulation 1223/2009
Entry: 1678

Chemical identity and properties

PubChem 2D chemical structure for CAS 10004-44-1
CAS 10004-44-1PubChem CID 24781

Hymexazol

Hymexazol is a member of the class of isoxazoles carrying hydroxy and methyl substituents at positions 3 and 5 respectively. It is used worldwide as a systemic soil and seed fungicide for the control of diseases caused by Fusarium, Aphanomyces, Pythium, and Corticium spp. in rice, sugarbeet, fodderbeet, vegetables, cucurbits, and ornamentals. It has a role as an antifungal agrochemical. It is a member of isoxazoles and a heteroaryl hydroxy compound. — ChEBI

IUPAC name
5-methyl-1,2-oxazol-3-one
Molecular formula
C4H5NO2
Molecular weight
99.09 g/mol
Exact mass
99.032028402 Da
XLogP3
0.1
Topological polar surface area
38.3 Ų
Hydrogen-bond donors
1
Hydrogen-bond acceptors
2
Covalent units
1
Defined stereocentres
0

Also known as

3-Hydroxy-5-methylisoxazole5-Methylisoxazol-3-olHymexazoleTachigarenHydroxyisoxazole5-Methyl-3-hydroxyisoxazole5-METHYL-3(2H)-ISOXAZOLONESF-6505
16 more reported names
F 319F-319NSC 2179715-methylisoxazol-3-one20T2M875LONSC-217971CHEBI:5827RTY-319RefChem:789581233-000-65-methylisoxazol-3(2H)-one3(2H)-Isoxazolone, 5-methyl-Itachigarden5-Methyl-isoxazol-3-ol3-Isoxazolol, 5-methyl-Hydroxyisoxazole (pesticide)
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Evidence from additional scientific databases

EMBL-EBI ChEBI
Exact identifier matchCHEBI:5827

hymexazol

A member of the class of isoxazoles carrying hydroxy and methyl substituents at positions 3 and 5 respectively. It is used worldwide as a systemic soil and seed fungicide for the control of diseases caused by Fusarium, Aphanomyces, Pythium, and Corticium spp. in rice, sugarbeet, fodderbeet, vegetables, cucurbits, and ornamentals.

Formula
C4H5NO2
Average mass
99.089 g/mol
Monoisotopic mass
99.03203 Da
Formal charge
0
  • heteroaryl hydroxy compound — is a (CHEBI:74818)
  • isoxazoles — is a (CHEBI:55373)
  • antifungal agrochemical — has role (CHEBI:86328)
  • antifungal agrochemical — has role (CHEBI:86328)
  • heteroaryl hydroxy compound — is a (CHEBI:74818)
  • isoxazoles — is a (CHEBI:55373)
Additional curated names
5-methyl-1,2-oxazol-3(2H)-one3-Hydroxy-5-methylisoxazole5-Methyl-3(2H)-isoxazolone5-Methyl-3-hydroxyisoxazole5-Methylisoxazol-3-olF 319F-319HydroxyisoxazoleHymexazoleNSC 217971SF-6505
Cross-references from this source
  • CAS: 10004-44-1 — KEGG COMPOUND
  • CAS: 10004-44-1 — ChemIDplus
  • MANUAL_X_REF: 388 — PPDB
  • MANUAL_X_REF: C11103 — KEGG COMPOUND
  • MANUAL_X_REF: hymexazol — Alan Wood's Pesticides
  • REGISTRY_NUMBER: 606046 — Reaxys

Mapped by: Exact CAS cross-reference in the ChEBI compound record. Source updated: 2015-07-07. Retrieved: 2026-08-31. Open source record

NIH PubChem PUG-View
Exact identifier match24781

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

  • Signal: Danger Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • GHS Hazard Statements: H302: Harmful if swallowed [Warning Acute toxicity, oral]; H317: May cause an allergic skin reaction [Warning Sensitization, Skin]; H318: Causes serious eye damage [Danger Serious eye damage/eye irritation]; H361d: Suspected of damaging the unborn child [Warning Reproductive toxicity]; H411: Toxic to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard] Source: Regulation (EC) No 1272/2008 of the European Parliament and of the Council
  • Precautionary Statement Codes: P203, P261, P264, P264+P265, P270, P272, P273, P280, P301+P317, P302+P352, P305+P354+P338, P317, P318, P321, P330, P333+P317, P362+P364, P391, 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: H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]; H317 (47.7%): May cause an allergic skin reaction [Warning Sensitization, Skin]; H318 (98.9%): Causes serious eye damage [Danger Serious eye damage/eye irritation]; H361 (14.8%): Suspected of damaging fertility or the unborn child [Warning Reproductive toxicity]; H361d (33%): Suspected of damaging the unborn child [Warning Reproductive toxicity]; H411 (47.7%): Toxic to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard]; H412 (51.1%): Harmful to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard] Source: European Chemicals Agency (ECHA)
  • Precautionary Statement Codes: P203, P261, P264, P264+P265, P270, P272, P273, P280, P301+P317, P302+P352, P305+P354+P338, P317, P318, P321, P330, P333+P317, P362+P364, P391, 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 88 reports by companies from 6 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: Hazardous Chemical Information System (HCIS), Safe Work Australia
  • GHS Hazard Statements: H302: Harmful if swallowed [Warning Acute toxicity, oral]; H317: May cause an allergic skin reaction [Warning Sensitization, Skin]; H318: Causes serious eye damage [Danger Serious eye damage/eye irritation]; H361d: Suspected of damaging the unborn child [Warning Reproductive toxicity]; H411: Toxic to aquatic life with long lasting effects [Hazardous to the aquatic environment, long-term hazard] Source: Hazardous Chemical Information System (HCIS), Safe Work Australia
  • Precautionary Statement Codes: P203, P261, P264, P264+P265, P270, P272, P273, P280, P301+P317, P302+P352, P305+P354+P338, P317, P318, P321, P330, P333+P317, P362+P364, P391, P405, and P501 (click each P-code to see the statement) Source: Hazardous Chemical Information System (HCIS), Safe Work Australia

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
EMBL-EBI ChEBIExact match2026-08-31
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.

Record details

Chemical name

Hymexazol (ISO); 3-hydroxy-5-methylisoxazole

Chemical / IUPAC name

Hymexazol (ISO); 3-hydroxy-5-methylisoxazole

Regulatory information

Regulation

(EU) 2021/1902

See every entry this act set

Key data

CAS
10004-44-1
EC
233-000-6
Annex
II
Entry number
1678

Direct matches are limited for this record, so nearby entries from Annex II are shown as well.

What Annex II means for Hymexazol (ISO); 3-hydroxy-5-methylisoxazole

Hymexazol (ISO); 3-hydroxy-5-methylisoxazole is listed as a prohibited substance under Annex II of EU Cosmetics Regulation 1223/2009 and must not be intentionally added. Article 17 separately addresses unintended small quantities that are technically unavoidable under good manufacturing practice and compatible with the Article 3 safety requirement.

Formulators must screen their ingredients and raw materials to ensure none contain this substance. Suppliers should provide documentation confirming absence when requested.

The page also surfaces 12 related annex records with overlapping identifiers, annex logic or naming patterns.

Compliance checklist

  • Verify this substance is absent from all raw materials and finished formulations.
  • Request absence confirmation or CoA from raw material suppliers.
  • Document the screening result in the Product Information File (PIF).

Frequently asked questions

Yes. Hymexazol (ISO); 3-hydroxy-5-methylisoxazole is listed in Annex II of EU Cosmetics Regulation 1223/2009 and is prohibited as an intentionally added cosmetic ingredient. Article 17 provides a narrow exception for unintended small quantities that are technically unavoidable under good manufacturing practice, provided the product remains safe under Article 3.

CAS 10004-44-1 is the unique numerical identifier assigned to Hymexazol (ISO); 3-hydroxy-5-methylisoxazole by the Chemical Abstracts Service. In cosmetic compliance work, the CAS number is used to cross-reference the substance across regulatory databases, raw material specifications and safety assessment reports. Multiple EU annex entries may share the same CAS number if the same substance appears under different conditions or in different annexes.

Use the INCI Checker tool on this site to paste your full ingredient list (INCI) and scan it against all Annex II–VI entries. The tool highlights any ingredients that match restricted, prohibited or allergen-flagged records. This is useful for rapid compliance screening of finished product formulas or raw material declarations.
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Source note for Annex II record Hymexazol (ISO); 3-hydroxy-5-methylisoxazole

This page summarizes one Annex II record for Hymexazol (ISO); 3-hydroxy-5-methylisoxazole from public European Commission cosmetic materials and adds linked inventory or identifier matches when available.

Use this record page to review Annex II conditions for Hymexazol (ISO); 3-hydroxy-5-methylisoxazole, but confirm any final regulatory decision against the current official annex wording and source files.

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