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4-METHOXYTOLUENE-2,5-DIAMINE HCL.

Avoid CAS 56496-88-9 / HAIR DYEING

A synthetic aromatic amine compound functioning as an oxidative colorant precursor, primarily used in permanent hair dyeing systems. This p-phenylenediamine derivative creates pigment polymers through oxidative coupling reactions but carries significant sensitization risks that limit its application in modern skincare formulations.

hair dyeing colorant precursor

Science

Functions through oxidative coupling chemistry where the compound reacts with oxidizing agents to form complex, high-molecular-weight pigment polymers that deposit color within hair structures or on skin surfaces


Research

High confidence
Effective range 0.1–4%
Optimal

N/A

Key findings

  1. 01 Demonstrated potent allergenic properties causing contact dermatitis in patch testing studies

Transparency

Not commonly dusted

Not applicable for skincare dusting analysis as this ingredient is restricted to hair coloring applications due to high sensitization potential


The Formula

Solubility
Water
Optimal pH 9 – 11
0 7 14

Stability

Requires highly alkaline conditions for stability; extremely photosensitive and oxidation-prone, causing discoloration when exposed to air or light

Synergies

  • Other aromatic amines for color development
  • Alkaline pH buffers for stability

Conflicts

  • Hydrogen peroxide (triggers reaction)
  • Acidic compounds
  • Reducing agents

Safety

CIR Status
Safe with restrictions
Max tested
4%
Pregnancy
Caution
Sensitization risk High

Classified as extremely potent skin sensitizer; restricted under European Commission regulations with specific usage limitations


Your Skin

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

Our Assessment

Avoid

High sensitization risk and regulatory restrictions make this ingredient unsuitable for precision skincare applications.


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