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Annex II Entry 1217 15/10/2010

4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products

4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products 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: 1217

Chemical identity and properties

PubChem 2D chemical structure for CAS 20055-01-0
CAS 20055-01-0PubChem CID 21904571

1H-Pyrazole, 4,5-diamine-1-methyl-, sulfate (1:1)

IUPAC name
1-methylpyrazole-4,5-diamine;sulfuric acid
Molecular formula
C4H10N4O4S
Molecular weight
210.21 g/mol
Exact mass
210.04227599 Da
Topological polar surface area
153.0 Ų
Hydrogen-bond donors
4
Hydrogen-bond acceptors
7
Covalent units
2
Defined stereocentres
0

Also known as

RefChem:438943836-860-61-Methyl-1H-pyrazole-4,5-diamine sulfate2-methylpyrazole-3,4-diamine;sulfuric acid4,5-diamino-1-methylpyrazole sulfate1H-Pyrazole-4,5-diamine, 1-methyl-, sulfate (1:1)1-Methyl-1H-pyrazole-45-diamine sulfate1-methyl-1H-pyrazole-4,5-diamine; sulfuric acid
11 more reported names
4,5-Diamino-1-methylpyrazole Sulfate; 4,5-Diamino-1-methylpyrazole Hydrosulfate1H-Pyrazole-4,5-diamine, 1-methyl-, sulfate1H-Pyrazole-4,5-diamine,DS-86541-Methyl-1H-pyrazole-4,5-diaminesulfateDA-219992-methylpyrazole-3,4-diamine; sulfuric acidCS-0080159EN300-3671474,5-diamino-1-methylpyrazole sulfuric acid salt1-Methyl-1H-pyrazole-4,5-diamine sulfate (1:1)
Open full PubChem recordPubChem annotations3D structure image

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

PubChem 2D chemical structure for CAS 21616-59-1
CAS 21616-59-1PubChem CID 13525020

1-Methyl-1H-pyrazole-4,5-diamine dihydrochloride

IUPAC name
1-methylpyrazole-4,5-diamine;dihydrochloride
Molecular formula
C4H10Cl2N4
Molecular weight
185.05 g/mol
Exact mass
184.0282517 Da
Topological polar surface area
69.9 Ų
Hydrogen-bond donors
4
Hydrogen-bond acceptors
3
Covalent units
3
Defined stereocentres
0

Also known as

2-methylpyrazole-3,4-diamine;dihydrochloride1-METHYL-1H-PYRAZOLE-4,5-DIAMINE 2HCL03FK8ORW3O4,5-Diamino-1-methylpyrazole hydrochloride4,5-Diamino-1-methylpyrazole dihydrochloride4,5-Diamino-1-methyl-1H-pyrazole dihydrochloride4,5-DIAMINO-1-METHYLPYRAZOLE HCLPyrazole, 4,5-diamino-1-methyl-, dihydrochloride
6 more reported names
1H-Pyrazole-4,5-diamine, 1-methyl-, dihydrochloride1H-Pyrazole-4,5-diamine, 1-methyl-, hydrochloride (1:2)UNII-03FK8ORW3O4,5-Diamino-1-methylpyrazole HCl [INCI]DB-1912071-Methyl-1H-pyrazole-4,5-diaminedihydrochloride
Open full PubChem recordPubChem annotations3D structure image
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

4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products

Regulatory information

Regulation

(EC) 2009/1223

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SCCS opinions

Identified ingredients

Key data

CAS
20055-01-0 / 21616-59-1
EC
- / -
Annex
II
Entry number
1217

Inventory links for 4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products

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

What Annex II means for 4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products

4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products 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.

This record is linked to 1 CosIng inventory ingredient for name and identifier cross-reference. 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. 4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products 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 20055-01-0 / 21616-59-1 is the unique numerical identifier assigned to 4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products 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 4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products

This page summarizes one Annex II record for 4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products 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 4,5-Diamino-1-methylpyrazole and its HCl salt, when used as a substance in hair dye products, but confirm any final regulatory decision against the current official annex wording and source files.

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