Why does CAS 623-43-8 appear in more than one EU cosmetic annex?

A substance identified by CAS 623-43-8 may appear in multiple EU cosmetic regulation annexes when it is subject to different conditions in different contexts — for example, restricted under Annex III with specific conditions, while also appearing in Annex IV as an approved colorant under separate entry conditions. Each entry must be reviewed individually.

How do I check if my formula contains a substance with CAS 623-43-8?

Use the INCI Checker on CosIng Checker with INCI names, CAS numbers or EC numbers. Paste CAS 623-43-8 to screen it directly, then review every linked annex record and supplier document.

CAS 1 record

CAS 623-43-8

Q: How do I use CAS 623-43-8 for compliance screening?

Cross-reference CAS 623-43-8 against your raw material specification sheets and CoA documents. When it appears in Annex II, verify absence. When it appears in Annex III, verify that concentration limits and product type conditions are met. All annex entries sharing this CAS number are listed on this page.

CAS 623-43-8 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 623-43-8

CAS 623-43-8PubChem CID 638132

Methyl Crotonate

Methyl 2-butenoate has been reported in Annona muricata and Carica papaya with data available. — LOTUS - the natural products occurrence database

IUPAC name: methyl (E)-but-2-enoate

Molecular formula: C5H8O2
Molecular weight: 100.12 g/mol
Exact mass: 100.052429494 Da
XLogP3: 0.9
Topological polar surface area: 26.3 Å²
Hydrogen-bond donors: 0
Hydrogen-bond acceptors: 2
Covalent units: 1
Defined stereocentres: 0

Also known as

(E)-Crotonic acid methyl esterMethyl E-crotonateMethyl 2-butenoateMethyl trans-crotonateMethyl trans-2-butenoateMethyl (E)-2-butenoatetrans-2-Butenoic acid methyl ester2-Butenoic acid, methyl ester, (2E)-

16 more reported names

Crotonic acid, methyl ester2-Butenoic acid, methyl ester, (E)-(E)-2-Butenoic acid methyl esterMethyl E-Propene-1-carboxylate2-Butenoic acid, methyl esterCROTONIC ACID, METHYL ESTER, (E)-1-(Methoxycarbonyl)propeneCrotonic Acid Methyl EsterEINECS 210-793-7BRN 17202923T02JIH93SEINECS 242-517-6NSC 18745(2E)-2-BUTENOIC ACID METHYL ESTERAI3-06008NSC-18745

Open full PubChem record PubChem annotations 3D structure image

External database identifiers

ChEMBL:CHEMBL3273387
EPA DTXSID:DTXSID10878813
PubMed:6517562

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 623-43-8

1 total

Annex

Entry

445

Methyl trans-2-butenoate, when used as a fragrance ingredient

210-793-7

How CAS 623-43-8 is used on this site

CAS 623-43-8 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 623-43-8 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 623-43-8 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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Tools & next steps

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