What does the restriction note for ETHYL THIOGLYCOLATE mean?

The restriction field for ETHYL THIOGLYCOLATE reads: III/2b. This is the restriction note from the CosIng inventory. For authoritative conditions and limits, always refer to the linked annex entries.

What other records share CAS 623-51-8?

CAS 623-51-8 may appear across multiple EU annex records. The CAS lookup page shows all Annex II–VI entries sharing this identifier, useful for identifying cross-annex regulatory status of the same chemical substance.

How do I check if my formula contains ETHYL THIOGLYCOLATE?

Use the INCI Checker to screen a full ingredient list across selected markets, or use the substance market comparison to review this identity across all supported market datasets.

InventoryRef 3385015/10/2010

ETHYL THIOGLYCOLATE

Ethyl mercaptoacetate

ETHYL THIOGLYCOLATE is linked to 1 EU annex record on this page. Inventory note: III/2b.

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Regulatory evidence by market

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Market	Evidence status	Records	Source language
European Union	Evidence linked Restricted entry found Open this evidence	1	English and EU languages
Great Britain	Source mapped Official source mapped; ingredient rule not imported	0	English
Canada	Source mapped Official source mapped; ingredient rule not imported	0	English and French
New Zealand	Source mapped Official source mapped; ingredient rule not imported	0	English
ASEAN	Source mapped Official source mapped; ingredient rule not imported	0	English and national languages
China	Source mapped Official source mapped; ingredient rule not imported	0	Chinese with selected English material
Japan	Source mapped Official source mapped; ingredient rule not imported	0	Japanese; official English translation available
South Korea	Source mapped Official source mapped; ingredient rule not imported	0	Korean with some English names
United States	Source mapped Official source mapped; ingredient rule not imported	0	English
Australia	Source mapped Official source mapped; ingredient rule not imported	0	English
Brazil	Source mapped Official source mapped; ingredient rule not imported	0	Portuguese with INCI crosswalks
India	Source mapped Official source mapped; ingredient rule not imported	0	English and Hindi
Saudi Arabia	Source mapped Official source mapped; ingredient rule not imported	0	Arabic and English

Chemical identity and properties

PubChem 2D chemical structure for CAS 623-51-8

CAS 623-51-8PubChem CID 12185

Ethyl Thioglycolate

Based on the available data, the CIR Expert Panel concluded that ... Ethyl Thioglycolate is safe for use in hair straighteners, permanent waves, tonics, dressings, and so forth, wave sets, other non-coloring hair products, and hair dyes and colors, as described in this safety assessment, at concentrations up to 15.2% (as Thioglycolic Acid). Hairdressers should avoid skin contact and minimize consumer skin exposure. — Cosmetic Ingredient Review (CIR)

IUPAC name: ethyl 2-sulfanylacetate

Molecular formula: C4H8O2S
Molecular weight: 120.17 g/mol
Exact mass: 120.02450067 Da
XLogP3: 0.8
Topological polar surface area: 27.3 Å²
Hydrogen-bond donors: 1
Hydrogen-bond acceptors: 3
Covalent units: 1
Defined stereocentres: 0

Also known as

Ethyl 2-mercaptoacetateEthyl mercaptoacetateUSAF EK-2070Thioglykolsaeure-aethylesterNSC 8834Ethyl .alpha.-mercaptoacetateAcetic acid, 2-mercapto-, ethyl ester2-mercaptoacetic acid ethyl ester

16 more reported names

UNII-Z5SD8DD6CPZ5SD8DD6CPEINECS 210-800-3Thioglykolsaeure-aethylester [German]BRN 0605581AI3-23030NSC-8834Ethyl alpha-mercaptoacetateETHOXYCARBONYLMETHANETHIOL4-03-00-00616 (Beilstein Handbook Reference)ACETIC ACID,MERCAPTO,ETHYL ESTERRefChem:139061ThioglykolsaeureaethylesterETHYL THIOGLYCOLATE [INCI]Acetic acid, mercapto, ethyl esterAcetic acid, 2mercapto, ethyl ester

Open full PubChem record PubChem annotations 3D structure image

External database identifiers

ChEMBL:CHEMBL3181965
EPA DTXSID:DTXSID8049337
PubMed:33358762
PubMed:22245853
PubMed:21950657
PubMed:21819121
PubMed:21581727
PubMed:16542026

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Inventory details for ETHYL THIOGLYCOLATE

INCI name

ETHYL THIOGLYCOLATE

Description

Ethyl mercaptoacetate

Record provenance

Inventory reference: 33850
Imported identity: ETHYL THIOGLYCOLATE
Source update: 15/10/2010

European Commission CosIng source notes

Annex records for ETHYL THIOGLYCOLATE

Annex III Restriction reference

Entry 2b

Thioglycolic acid esters

Key data

CAS

623-51-8

210-800-3

Restriction

III/2b

Function

DEPILATORY: Breaking down the mechanical strength of hair fibers so that they can be removed by mild scraping/rubbing.
HAIR WAVING OR STRAIGHTENING: Modifying the chemical structure of the hair, allowing it to be set in the style required (permanent waves or hair straightening).
REDUCING: Changing the chemical nature of another ingredient by adding hydrogen (or removing oxygen).

Official EU ingredient-name evidence

The ingredient name exactly matches the official 2025 EU glossary of common ingredient names.

#10127 · ETHYL THIOGLYCOLATE

Ingredients with overlapping formulation functions

DICYCLOPENTADIENE/ISOPENTENE/ISOPRENE/STYRENE COPOLYMERBINDING, DEPILATORY, PLASTICISER

DIETHYLENE GLYCOL ROSINATEBINDING, BULKING, DEPILATORY, FILM FORMING, PLASTICISER

DIMETHYLAMINOPROPYLAMINO HYPOCRELLIN BDEPILATORY

ETHANOLAMINE THIOGLYCOLATEDEPILATORY, HAIR WAVING OR STRAIGHTENING, REDUCING

HYDROGENATED DICYCLOPENTADIENE/ISOPENTENE/ISOPRENE COPOLYMERBINDING, DEPILATORY, PLASTICISER

HYDROGENATED DICYCLOPENTADIENE/ISOPENTENE/ISOPRENE/STYRENE COPOLYMERBINDING, DEPILATORY, PLASTICISER

HYDROGENATED POLYCYCLOPENTADIENEDEPILATORY

HYDROGENATED POLYDICYCLOPENTADIENEBINDING, DEPILATORY

Additional official and scientific sources

11 external databases to check this identity in

Each link searches that source for this identity. What each source is, and its legal weight

ECHA CHEM / Information on chemicals PubChem PUG REST EU Safety Gate cosmetic product alerts ECHA CHEM US EPA CompTox Cosmetic Ingredient Review safety assessments FDA Global Substance Registration System ILO/WHO International Chemical Safety Cards Japan NITE-CHRIP NIOSH Pocket Guide to Chemical Hazards OECD eChemPortal

How ETHYL THIOGLYCOLATE appears in the CosIng inventory

The CosIng inventory lists ETHYL THIOGLYCOLATE as a cosmetic ingredient and this page links it to 1 annex record. The inventory entry captures names and identifiers, while the annex record shows where the substance is prohibited, restricted or positively listed in EU cosmetics law.

ETHYL THIOGLYCOLATE is also tagged with 3 cosmetic functions in the official data. Function labels describe intended use, but they do not replace regulatory review of linked annex records before formulation or labelling work.

Frequently asked questions

ETHYL THIOGLYCOLATE appears in the EU CosIng inventory and has linked annex records. Check the annex records above for applicable restrictions, concentration limits and conditions of use. Annex II listing means prohibited; Annex III means restricted; Annexes IV, V and VI mean permitted under specified conditions.

The restriction field for ETHYL THIOGLYCOLATE reads: "III/2b". This is the restriction note recorded in the CosIng inventory for this ingredient. For authoritative conditions and limits, always refer to the linked annex entries above.

According to the EU CosIng inventory, ETHYL THIOGLYCOLATE carries the following function designation(s):

CAS 623-51-8 may appear across multiple EU annex records. Viewing the CAS lookup page shows all Annex II–VI entries sharing this identifier, which is useful for identifying cross-annex regulatory status of the same chemical substance.

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Source note for ETHYL THIOGLYCOLATE

This page combines the CosIng inventory entry for ETHYL THIOGLYCOLATE with 1 linked Annex II–VI record from the local dataset built from public European Commission cosmetic ingredient materials.

Use this inventory page to research ETHYL THIOGLYCOLATE and compare linked records, but verify restrictions and legal status against the current official source text and law before making regulatory decisions.

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