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CAS 66-81-9

CAS 66-81-9 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 66-81-9
CAS 66-81-9PubChem CID 6197

Cycloheximide

Cycloheximide is a dicarboximide that is 4-(2-hydroxyethyl)piperidine-2,6-dione in which one of the hydrogens attached to the carbon bearing the hydroxy group is replaced by a 3,5-dimethyl-2-oxocyclohexyl group. It is an antibiotic produced by the bacterium Streptomyces griseus. It has a role as an anticoronaviral agent, a ferroptosis inhibitor, a protein synthesis inhibitor, a neuroprotective agent and a bacterial metabolite. It is a dicarboximide, a secondary alcohol, a cyclic ketone, a member of piperidones, a piperidine antibiotic and an antibiotic fungicide. It is functionally related to a piperidine-2,6-dione. — ChEBI

IUPAC name
4-[(2R)-2-[(1S,3S,5S)-3,5-dimethyl-2-oxocyclohexyl]-2-hydroxyethyl]piperidine-2,6-dione
Molecular formula
C15H23NO4
Molecular weight
281.35 g/mol
Exact mass
281.16270821 Da
XLogP3
0.5
Topological polar surface area
83.5 Ų
Hydrogen-bond donors
2
Hydrogen-bond acceptors
4
Covalent units
1
Defined stereocentres
4

Also known as

ACTIDIONECicloheximideNARAMYCIN AActidionHizarocinNaramycinKakenActi-Aid
16 more reported names
ActidoneNeocycloheximideCicloheximidaActisprayActi-DioneActidione PMCicloheximidumNSC-185Actidione BRActidione TGFU-4527AktidionNSC 185(-)-CycloheximideNM-MCD 80CBC 500046
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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.

Records for CAS 66-81-9

1 total

How CAS 66-81-9 is used on this site

CAS 66-81-9 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 66-81-9 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 66-81-9 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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