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Moumoujus

2-CHLORO-P-PHENYLENEDIAMINE.

Avoid CAS 615-66-7 / HAIR DYEING

A synthetic aromatic amine compound primarily used as an oxidative hair dye precursor that forms permanent color molecules within hair structures. This ingredient operates through chemical oxidation to create stable pigment complexes, but carries significant sensitization risks that have led to regulatory restrictions. While effective for hair coloring applications, its safety profile limits broader cosmetic use.

Summary

hair dyeing

Science

Mechanism of Action

Functions as a primary intermediate in oxidative hair dyeing by diffusing into hair shafts where it undergoes oxidation with hydrogen peroxide to form large quinonimine pigment molecules that become permanently trapped within the hair structure.

Research

Clinical Evidence

Medium confidence
Effective range 1–4.6%
Optimal

1%

Key findings

  1. 01 Mild conjunctival inflammation in ocular tests, non-sensitizing in some rabbit models
  2. 02 Strong sensitizer classification in guinea pig maximization tests

Transparency

Dusting Analysis

Not commonly dusted
Red flag below
1%

Not applicable for dusting as this is a specialized hair dye intermediate with strict regulatory limits and significant sensitization concerns

The Formula

Formulation

Solubility
Both
Optimal pH 7 – 10
0 7 14

Stability

Highly unstable when exposed to air and light, oxidizing rapidly to form purple then black coloration. Requires two-part formulation systems with immediate pre-use mixing to maintain stability.

Synergies

  • Hydrogen peroxide (oxidizing agent)

Conflicts

  • Strong oxidizing agents
  • Strong acids
  • Iron (III) chloride

Safety

Safety Profile

CIR Status
Safe with restrictions
Max tested
1%
Pregnancy
Caution
Sensitization risk High

Banned in EU for eyebrow and eyelash applications due to sensitization concerns and insufficient safety data. CIR approval limited to hair dye use below 1.0% concentration.

Your Skin

Skin Compatibility

No Normal
No Dry
No Oily
No Sensitive
Irritancy Low
Comedogenicity Unknown

Our Assessment

Verdict

Avoid

A high-risk sensitizing ingredient with severe regulatory restrictions that make it unsuitable for precision skincare applications.

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