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Annex II Entry 426 20/10/2010

Diethyl maleate, when used as a fragrance ingredient

Diethyl maleate, when used as a fragrance ingredient 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: 426

Chemical identity and properties

PubChem 2D chemical structure for CAS 141-05-9
CAS 141-05-9PubChem CID 5271566

Diethyl Maleate

Diethyl maleate is a maleate ester resulting from the formal condensation of both carboxy groups of maleic acid with ethanol. A colourless liquid at room temperature (m.p. -10C) with boiling point 220C at 1 atm., it is commonly used as a dienophile for Diels-Alder-type cycloaddition reactions in organic synthesis. It has a role as a glutathione depleting agent. It is an ethyl ester and a maleate ester. It is functionally related to an ethanol. — ChEBI

IUPAC name
diethyl (Z)-but-2-enedioate
Molecular formula
C8H12O4
Molecular weight
172.18 g/mol
Exact mass
172.07355886 Da
XLogP3
0.9
Topological polar surface area
52.6 Ų
Hydrogen-bond donors
0
Hydrogen-bond acceptors
4
Covalent units
1
Defined stereocentres
0

Also known as

DiethylmaleateMaleic acid, diethyl ester2-Butenedioic acid (2Z)-, diethyl esterDiethylester kyseliny maleinoveG81WQB56OLSTAFLEX DEMNSC-8394CHEBI:68508
16 more reported names
RefChem:133422diethyl maleic acid diester205-451-9Maleic acid diethyl ester2-Butenedioic acid (Z)-, diethyl esterDiethyl (Z)-2-butenedioatediethyl (2Z)-but-2-enedioate2-Butenedioic acid, diethyl ester, (Z)-2-Butenedioic acid, diethyl ester, (2Z)-Diethyl (2E)-2-butenedioate2-Butenedioic acid (2Z)-, 1,4-diethyl esterdiethyl (2Z)but-2-ene-1,4-dioateCAS-141-05-9CCRIS 941WLN: 2OV1U1VO24-02-00-02207 (Beilstein Handbook Reference)
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External database identifiers

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

Diethyl maleate, when used as a fragrance ingredient

Chemical / IUPAC name

2-Butenedioic acid (2Z)-, 1,4-diethyl ester

Regulatory information

Regulation

(EC) 2009/1223

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SCCS opinions

Key data

CAS
141-05-9
EC
205-451-9
Annex
II
Entry number
426

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

What Annex II means for Diethyl maleate, when used as a fragrance ingredient

Diethyl maleate, when used as a fragrance ingredient 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. Diethyl maleate, when used as a fragrance ingredient 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 141-05-9 is the unique numerical identifier assigned to Diethyl maleate, when used as a fragrance ingredient 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 Diethyl maleate, when used as a fragrance ingredient

This page summarizes one Annex II record for Diethyl maleate, when used as a fragrance ingredient 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 Diethyl maleate, when used as a fragrance ingredient, but confirm any final regulatory decision against the current official annex wording and source files.

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