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2-NITRO-P-PHENYLENEDIAMINE.

Avoid CAS 5307-14-2 / HAIR DYEING

A small-molecule nitro dye compound primarily utilized in hair coloring applications that functions without requiring oxidative activation. This ingredient rapidly penetrates hair shafts and undergoes extensive metabolic conversion when in contact with skin tissue.

hair dyeing

Science

Functions as a direct-acting colorant that penetrates the hair shaft structure without oxidative coupling requirements. Upon skin contact, undergoes rapid absorption and metabolic transformation via nitroreduction and acetylation pathways, converting to triaminobenzene and N4-acetyl derivatives.


Research

High confidence
Effective range 0.48–1.1%
Optimal

1.1%

Key findings

  1. 01 Chronic 117-week topical study at 1.1% showed no tumor incidence increase
  2. 02 Skin penetration measured at 3.2 µg/cm² with 0.48% concentration
  3. 03 Primary Skin Irritation Index of 0 at 2.5% concentration in rabbits

Transparency

Not commonly dusted

Not applicable for skincare formulations as this ingredient is exclusively used in hair coloring products


The Formula

Solubility
Both
Optimal pH 7 – 10
0 7 14

Stability

Maintains stability in solid form but susceptible to oxidative degradation in solution with potential formation of reactive imine intermediates. Enhanced solubility observed in heated water and ethanol systems.

Conflicts

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

Safety

CIR Status
Safe as used
Max tested
1.1%
Sensitization risk High

CIR reaffirmed safety in 2003 for non-sensitized individuals but classified as potent skin sensitizer. Prohibited in EU (Annex II) while permitted in US and UK markets.


Your Skin

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

Our Assessment

Avoid

While technically safe at regulated concentrations, its potent sensitization potential and hair-specific application make it unsuitable for precision skincare formulations.


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