2,4-Diaminophenol Dihydrochloride
AKA “Acrol, 2, 4-Diaminophenol hydrochloride, Phenol, 4-diamino-, dihydrochloride, 4-Diaminophenol HCl, Diamidophenol hydrochloride, hydrochloride (1:2), NCI-C60026, T1IYY101NX, DTXSID9020401”
Ingredient
Ingredient Facts
2,4-diaminophenol dihydrochloride
AKA: Acrol, 4-Diaminophenol hydrochloride, 4-diamino-, 4-Diaminophenol HCl, Diamidophenol hydrochloride, Hydrochloride (1:2), NCI-C60026, T1IYY101NX, DTXSID9020401
Ingredient · Solvent · EWG: 4
Synthetic
Solvent
Not Clean
On the basis of the data included in this report, the CIR Expert Panel concludes that 2,4-Diaminophenol and 2,4-Diaminophenol Dihydrochloride are safe for use in hair dyes at concentrations up to 0.2% (as the free base). 2009 RE-REVIEW - The Expert Panel noted that 2,4-Diaminophenol Dihydrochloride is now termed 2,4-Diaminophenol Hydrochloride.
Solubility greater than or equal to 100 mg/mL at 74.3 °F (NTP, 1992)
Formula
C6H10Cl2N2O
Mol. Weight
197.06
CAS #
137-09-7
Form
Powder
State
Grayish-white crystals. (NTP, 1992)
See origin →
Functions
Solvent
Dissolves other ingredients so they distribute evenly in the formula. Often the invisible "base" everything else is mixed into.
Traditional Use
A stabilized salt form of 2,4-diaminophenol developed for hair coloring formulations. The hydrochloride salt improves stability and shelf-life compared to the free base form.
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
No
2-Amino-4-nitrophenol.
IARC monographs on the evaluation of carcinogenic risks to humans, 1993
2-Amino-5-nitrophenol.
IARC monographs on the evaluation of carcinogenic risks to humans, 1993
4-amino-2-nitrophenol.
IARC monographs on the evaluation of the carcinogenic risk of chemicals to man, 1978
Polyphenols: skin photoprotection and inhibition of photocarcinogenesis.
Afaq F, Katiyar SK
Mini reviews in medicinal chemistry, 2011
Polyphenols: skin photoprotection and inhibition of photocarcinogenesis.
Afaq F, Katiyar SK
Mini reviews in medicinal chemistry, 2011
Potential skin anti-aging effects of main phenolic compounds, tremulacin and tremuloidin from Salix chaenomeloides leaves on TNF-α-stimulated human de
Ahn SY, Kim KA, Lee S, Kim KH
Chemico-biological interactions, 2024
Efficacy of a topical polyphenol-based formulation in palmoplantar psoriasis: an observational study.
Amato S, Dattola A, Bennardo L, Tolone M, Nisticò SP
Dermatology reports, 2025
Efficacy of a topical polyphenol-based formulation in palmoplantar psoriasis: an observational study.
Amato S, Dattola A, Bennardo L, Tolone M, Nisticò SP
Dermatology reports, 2025
Final report on the safety assessment of amino nitrophenols as used in hair dyes.
Burnett CL, Bergfeld WF, Belsito DV, Klaassen CD, Marks JG Jr et al.
International journal of toxicology, 2009
Final report on the safety assessment of amino nitrophenols as used in hair dyes.
Burnett CL, Bergfeld WF, Belsito DV, Klaassen CD, Marks JG Jr et al.
International journal of toxicology, 2009
Final report on the safety assessment of amino nitrophenols as used in hair dyes.
Burnett CL, Bergfeld WF, Belsito DV, Klaassen CD, Marks JG Jr et al.
International journal of toxicology, 2009
Final Amended Report on the Safety Assessment of p-Methylaminophenol Sulfate and p-Methylaminophenol
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of 2-Amino-6-Chloro-4-Nitrophenol and 2-Amino-6-Chloro-4-Nitrophenol Hydrochloride
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of 2-Methyl-5-Hydroxyethylaminophenol
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of 2,4-Diaminophenol and 2,4-Diaminophenol Dihydrochloride
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of 2,4-Diaminophenoxyethanol Dihydrochloride
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of 6-Amino-m-Cresol, 6-Amino-o-Cresol, 4-Amino-m-Cresol, 5-Amino-4-Chloro-o-Cresol, 5-Amino-6-Chloro-o-Cresol and 4-Chloro-2-Aminophenol
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of Amino Nitrophenols Used in Hair Dyes
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of Chlorhexidine/Chlorhexidine Diacetate/Chlorhexidine Dihydrochloride/Chlorhexidine Digluconate
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of p-Aminophenol, m-Aminophenol, and o-Aminophenol
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of p-Methylaminophenol Sulfate
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of Sodium p-Chloro-m-Cresol, p-Chloro-m-Cresol, Chlorothymol, Mixed Cresols, m-Cresol, o-Cresol, p-Cresol, Isopropyl Cresols, Thymol, o-Cymen-5-ol and Carvacrol
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report on the Safety Assessment of Zinc Phenolsulfonate
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report: Amended Safety Assessment of 4-Chloro-2-Aminophenol as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report: Safety Assessment of Sodium Benzotriazolyl Butylphenol Sulfonate as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Final Report: Safety Assessment of Tetrabromophenol Blue as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Note Regarding the Safety Assessment of Chlorhexidine, Chlorhexidine Diacetate, Chlorhexidine Digluconate, and Chlorhexidine Dihydrochloride
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Zinc Phenolsulfonate
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
2-Amino-6-Chloro-4-Nitrophenol
European Commission
EU Cosmetic Ingredient Database (CosIng)
2-Methyl-5-Hydroxyethylaminophenol
European Commission
EU Cosmetic Ingredient Database (CosIng)
3-Nitro-p-Hydroxyethylaminophenol
European Commission
EU Cosmetic Ingredient Database (CosIng)
4-Amino-3-Nitrophenol
European Commission
EU Cosmetic Ingredient Database (CosIng)
4-Hydroxypropylamino-3-Nitrophenol
European Commission
EU Cosmetic Ingredient Database (CosIng)
Carvacrol
European Commission
EU Cosmetic Ingredient Database (CosIng)
Chlorhexidine Dihydrochloride
European Commission
EU Cosmetic Ingredient Database (CosIng)
Sodium Acrylate/Acrolein Copolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
Sodium Acrylates/Acrolein Copolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
Sodium Benzotriazolyl Butylphenol Sulfonate
European Commission
EU Cosmetic Ingredient Database (CosIng)
Zinc Phenolsulfonate
European Commission
EU Cosmetic Ingredient Database (CosIng)
2-Amino-5-Nitrophenol
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
2-Amino-6-Chloro-4-Nitrophenol
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
2-Methyl-5-Hydroxyethylaminophenol
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
3-Nitro-p-Hydroxyethylaminophenol
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
4-Amino-3-Nitrophenol
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
4-Hydroxypropylamino-3-Nitrophenol
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Carvacrol
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Chlorhexidine Dihydrochloride
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Sodium Benzotriazolyl Butylphenol Sulfonate
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Zinc Phenolsulfonate
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
2-Amno-6-Chloro-4-Nitrophenol.
Fiume MM
International journal of toxicology, 2017
Novel Bioactive Multifunctional Polyphenols: A Chemo-Enzymatic Approach.
Flourat AL, Thiébault E, Martinez A, Brunissen F, Dosso A et al.
Chemistry (Weinheim an der Bergstrasse, Germany), 2026
Fate and effects of acrolein.
Ghilarducci DP, Tjeerdema RS
Reviews of environmental contamination and toxicology, 1995
2-Amino-1,2-bis(4-methoxyphenol) ethanol and its salts
Health Canada
Health Canada Cosmetic Ingredient Hotlist
2-Amino-4-nitrophenol
Health Canada
Health Canada Cosmetic Ingredient Hotlist
2-Amino-5-nitrophenol
Health Canada
Health Canada Cosmetic Ingredient Hotlist
4-Amino-2-nitrophenol
Health Canada
Health Canada Cosmetic Ingredient Hotlist
4-Benzyloxyphenol
Health Canada
Health Canada Cosmetic Ingredient Hotlist
4-Ethoxyphenol
Health Canada
Health Canada Cosmetic Ingredient Hotlist
4-tert-Butylphenol
Health Canada
Health Canada Cosmetic Ingredient Hotlist
4,4'-Isopropylidenediphenol
Health Canada
Health Canada Cosmetic Ingredient Hotlist
Dinitrophenol isomers
Health Canada
Health Canada Cosmetic Ingredient Hotlist
Phenol
Health Canada
Health Canada Cosmetic Ingredient Hotlist
Phenolphthalein
Health Canada
Health Canada Cosmetic Ingredient Hotlist
Occupational allergic contact dermatitis caused by epoxy diacrylate in ultraviolet-light-cured paint, and bisphenol A in dental composite resin.
Jolanki R, Kanerva L, Estlander T
Contact dermatitis, 1995
Effects of antioxidant polyphenols on TNF-alpha-related diseases.
Kawaguchi K, Matsumoto T, Kumazawa Y
Current topics in medicinal chemistry, 2011
Effects of antioxidant polyphenols on TNF-alpha-related diseases.
Kawaguchi K, Matsumoto T, Kumazawa Y
Current topics in medicinal chemistry, 2011
Effects of antioxidant polyphenols on TNF-alpha-related diseases.
Kawaguchi K, Matsumoto T, Kumazawa Y
Current topics in medicinal chemistry, 2011
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Kim HH, Jeong SH, Park MY, Bhosale PB, Abusaliya A et al.
Scientific reports, 2023
Antioxidant effects of phenolic compounds in through the distillation of Lonicera japonica & Chenpi extract and anti-inflammation on skin keratinocyte
Kim HH, Jeong SH, Park MY, Bhosale PB, Abusaliya A et al.
Scientific reports, 2023
Antioxidant effects of phenolic compounds in through the distillation of Lonicera japonica & Chenpi extract and anti-inflammation on skin keratinocyte
Kim HH, Jeong SH, Park MY, Bhosale PB, Abusaliya A et al.
Scientific reports, 2023
Antioxidant effects of phenolic compounds in through the distillation of Lonicera japonica & Chenpi extract and anti-inflammation on skin keratinocyte
Kim HH, Jeong SH, Park MY, Bhosale PB, Abusaliya A et al.
Scientific reports, 2023
Analytical Method Development and Dermal Absorption of 4-Amino-3-Nitrophenol (4A3NP), a Hair Dye Ingredient under the Oxidative or Non-Oxidative Condi
Kim HY, Kim YJ, Lee JD, Kim HR, Seo DW
Toxics, 2024
Molecular modeling and phenoloxidase inhibitory activity of arbutin and arbutin undecylenic acid ester.
Masyita A, Salim E, Asri RM, Nainu F, Hori A et al.
Biochemical and biophysical research communications, 2021
Sargassum horneri extract containing polyphenol alleviates DNCB-induced atopic dermatitis in NC/Nga mice through restoring skin barrier function.
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Histology and histopathology, 2022
Microwave-Assisted Extraction of Phenolic Compounds and Antioxidants for Cosmetic Applications Using Polyol-Based Technology.
Myat Win S, Saelee M, Myo H, Khat-Udomkiri N
Journal of visualized experiments : JoVE, 2024
Microwave-Assisted Extraction of Phenolic Compounds and Antioxidants for Cosmetic Applications Using Polyol-Based Technology.
Myat Win S, Saelee M, Myo H, Khat-Udomkiri N
Journal of visualized experiments : JoVE, 2024
Allergic contact dermatitis due to nonylphenol ethoxylate (nonoxynol-6).
Nethercott JR, Lawrence MJ
Contact dermatitis, 1984
Lingonberry (Vaccinium vitis-idaea L.) Fruit Phenolic Bio...
Pirjo Pärnänen, Sari Niikko, Hanna Lähteenmäki, Ismo T Räisänen, Taina Tervahartiala, Timo Sorsa + 1 more
Microorganisms, 2024
Phenolic Composition and Biological Properties of Wild and Commercial Dog Rose Fruits and Leaves.
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Molecules (Basel, Switzerland), 2020
Antioxidant capacity, phenolic content, and profiling of phenolic compounds in the seeds, skin, and pulp of Vitis rotundifolia (Muscadine Grapes) As d
Sandhu AK, Gu L
Journal of agricultural and food chemistry, 2010
Phenolic-enriched maple syrup extract protects human keratinocytes against hydrogen peroxide and methylglyoxal induced cytotoxicity.
Sheng J, Liu C, Petrovas S, Wan Y, Chen HD et al.
Dermatologic therapy, 2020
Chlorhexidine Dihydrochloride Shows Anti-tumor Effects in Desmoid Tumors and Colorectal Cancer.
Shin H, Kim Y, Lee Y, Kim J, Ryu YC et al.
Anticancer research, 2024
Allergy to 3-nitro-p-hydroxyethylaminophenol and 4-amino-3-nitrophenol in a hair dye.
Søsted H, Menné T
Contact dermatitis, 2005
Protective Role of Phenolic Compounds from Whole Cardamom (Elettaria cardamomum (L.) Maton) against LPS-Induced Inflammation in Colon and Macrophage C
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Nutrients, 2023
Antioxidant screening and phenolic content of ethanol extracts of selected Baja California Peninsula macroalgae.
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Journal of food science and technology, 2017
Zinc Phenolsulfonate.
Tucker R, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2024
Severe contact urticarial syndrome due to oxidative hair dye containing para-aminophenol and sodium-methyl-oleoyl-taurate.
Uehara S, Inomata N, Suzuki A, Matsuura M, Aihara M
The Journal of dermatology, 2014
Extraction of Polyphenols and Vitamins Using Biodegradable ATPS Based on Ethyl Lactate.
Velho P, Marques L, Macedo EA
Molecules (Basel, Switzerland), 2022
Profiling and quantification of phenolic compounds in Camellia seed oils: Natural tea polyphenols in vegetable oil.
Wang X, Zeng Q, Del Mar Contreras M, Wang L
Food research international (Ottawa, Ont.), 2017
Profiling and quantification of phenolic compounds in Camellia seed oils: Natural tea polyphenols in vegetable oil.
Wang X, Zeng Q, Del Mar Contreras M, Wang L
Food research international (Ottawa, Ont.), 2017
Formulation of Propolis Phenolic Acids Containing Microemulsions and Their Biopharmaceutical Characterization.
Žilius M, Ramanauskienė K, Juškaitė V, Briedis V
Evidence-based complementary and alternative medicine : eCAM, 2016
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR