Get a Free 5ml Mini Now Free 5ml Mini With Every Order of The Mantle

2,4-DIAMINOPHENOXYETHANOL HCL.

Questionable CAS 66422-95-5 / HAIR DYEING

A water-soluble intermediate compound primarily utilized in oxidative hair coloring systems as a coupler agent. This ingredient works through nucleophilic reactions with primary intermediates to generate stable, large-molecule pigments that provide lasting color within hair structures.

Hair dyeing Color coupling

Science

Functions as a secondary intermediate in oxidative coloring reactions, combining with primary precursors in the presence of hydrogen peroxide to create complex pigment molecules too large to wash out of hair shafts


Research

High confidence
Effective range 2–4%
Optimal

2%

Key findings

  1. 01 CIR safety assessment at 4.0% showed minimal eye irritation and slight skin irritation in animal models
  2. 02 SCCS evaluation established 2.0% as maximum safe concentration for on-head hair dye applications
  3. 03 LLNA testing revealed EC3 value of 3.2%, classifying moderate sensitization potential

Transparency

Not commonly dusted

Specialized hair coloring agent not typically subject to concentration inflation in cosmetic formulations


The Formula

Solubility
Water
Optimal pH 2.1 – 8.5
0 7 14

Stability

Maintains stability for 6 hours at ambient temperature and 9 days refrigerated when shielded from light under inert atmosphere; sulfate salt exhibits enhanced solubility at acidic pH 2.1

Synergies

  • Primary hair dye intermediates
  • Hydrogen peroxide oxidizing systems

Conflicts

  • Strong light exposure
  • Atmospheric oxygen
  • Oxidizing agents outside controlled coloring reactions

Safety

CIR Status
Safe with restrictions
Max tested
2%
Sensitization risk Moderate

Requires patch testing and caution labeling under FD&C Act as coal tar derivative; restricted to hair dye applications at concentrations not exceeding 2%


Your Skin

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

Our Assessment

Questionable

Specialized hair coloring ingredient with moderate sensitization risk and strict regulatory limitations unsuitable for general skincare applications.


Related

Finding similar ingredients…