HC Blue No. 2
molecular structure · PubChem
AKA: 33229-34-4, HC Blue 2, NCI-C54897, Ethanol, N4-Tris(2-hydroxyethyl)-2-nitro-p-phenylenediamine, COVARINE BLUE W 6122
Allergen Warning
⚠️ PPD (Hair Dye)
Synthetic
Not Clean
2,2'-[[4-[(2-Hydroxyethyl)amino]-3-nitrophenyl]imino]bisethanol
Solubility less than 1 mg/mL at 75 °F (NTP, 1992)
Formula
C12H19N3O5
Mol. Weight
285.30
CAS #
33229-34-4
Form
Powder
State
Hc blue 2 is a dark blue to dark brown microcrystalline powder. (NTP, 1992)
Functions
Hair Dyeing
Colors Hair
Traditional Use
A synthetic aromatic dye developed for the hair care industry in the mid-20th century to provide blue coloring in semi-permanent hair color products with improved stability and fade resistance.
EWG
4
CIR
Safe as used
Pregnancy
Caution
CIR Safety Findings
medical-approval
all-shades-safe
Concentration Guide
2.8%
0%4%
Reg. Limit
EU regulatory limit: 2.8%. Can cause allergic reaction Source: EU Cosmetics Regulation (EC) 1223/2009, Annex III (Restricted Substances), Entry 247.
Regulatory Agencies
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Caution
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed1 review →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR