4-Aminophenol hydrochloride

Overview IFRA Request a quote

  • Identifiers

    CAS number
    51-78-5

    Molecular formula
    C6H8ClNO

    SMILES
    C1=CC(=CC=C1N)O.Cl

    Safety labels

    Irritant
    Irritant

  • Odor profile

    Fragrance
    Phenolic 71.29%
    Sweet 45.83%
    Smoky 44.12%
    Medicinal 43.48%
    Burnt 39.27%
    Animal 38.56%
    Meaty 36.88%
    Musty 31.77%
    Bitter 28.81%
    Leathery 26.96%

     

    Flavor
    Phenolic 65.67%
    Medicinal 41.48%
    Mild 35.29%
    Meaty 35.28%
    Phenol 33.41%
    Sulfurous 29.75%
    Garlic 25.51%
    Smoke 24.91%
    Penetrating 24.65%
    Medical 24.63%

     

    Odor impact est.
    Low

  • Properties

    pKa est.
    7.78 (neutral)

    Molecular weight
    145.59 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra slow

    Boiling point est.
    292°C

    Melting point expt.

    • 306 °C, decomposes

    Flash point

    • 145.07 ˚C est.

    Solubility expt.

    • Very sol in water; sol in alcohol

  • Synonyms

    • 4-Aminophenol hydrochloride
    • 51-78-5
    • P-AMINOPHENOL HYDROCHLORIDE
    • Futramine P
    • Fourrine 83
    • Phenol, 4-amino-, hydrochloride
    • Fouramine CP
    • Fourrine P
    • Durafur Brown R
    • Pelagol CP
    • Peltol P
    • Pelagol Grey CP
    • Furro P
    • p-AMINOPHENOL HCl
    • p-Hydroxyaniline hydrochloride
    • CI Oxidation Base 6A
    • C.I. Oxidation Base 6A
    • IWL2N22RFY
    • CI 76551
    • Phenol, p-amino-, hydrochloride
    • RODOL PC
    • C.I. 76551
    • DTXSID6058760
    • RefChem:518264
    • DTXCID7040948
    • 200-122-6
    • 4-Hydroxyanilinium chloride
    • 4-Hydroxyaniline hydrochloride
    • 4-aminophenol;hydrochloride
    • MFCD00012996
    • Phenol, 4-amino-, hydrochloride (1:1)
    • HSDB 2151
    • EINECS 200-122-6
    • UNII-IWL2N22RFY
    • AI3-00317
    • 4-aminophenol, chloride
    • CHEMBL388353
    • SCHEMBL1886379
    • 4-Aminophenol hydrochloride, powder
    • EBC-06150
    • AKOS015889972
    • 4-Aminophenol--hydrogen chloride (1/1)
    • BS-44198
    • P-AMINOPHENOL HYDROCHLORIDE [HSDB]
    • DB-052023
    • A0392
    • ST50823997
    • EN300-18027
    • D88257
    • F104900
    • Q27280927
    • 4-Aminophenol hydrochloride, for photographic purposes, >=99.0% (AT)
    • 4-Aminophenol hydrochloride, Pharmaceutical Secondary Standard; Certified Reference Material
    • 51-78-5

  • Applications

    4-Aminophenol hydrochloride is primarily used as an organic synthesis intermediate in pharmaceutical and colorant applications. In pharmaceuticals, it is a key starting material for the production of paracetamol (acetaminophen). In the dyes and pigments sector, it acts as a precursor for oxidation-type hair dyes and other aromatic colorants, and as a building block for pigment and coating formulations used in textiles, coatings, and inks. It also serves as a general synthetic building block for various specialty chemicals in industrial manufacturing. The hydrochloride salt form provides improved stability and handling, with actual use subject to local regulations and formulation limits.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 53.09
    methanol 101.46
    isopropanol 28.44
    water 20.54
    ethyl acetate 32.24
    n-propanol 31.1
    acetone 56.27
    n-butanol 23.97
    acetonitrile 23.15
    DMF 154.96
    toluene 1.55
    isobutanol 16.81
    1,4-dioxane 30.43
    methyl acetate 40.23
    THF 188.87
    2-butanone 34.51
    n-pentanol 21.91
    sec-butanol 17.88
    n-hexane 0.37
    ethylene glycol 48.0
    NMP 59.0
    cyclohexane 0.17
    DMSO 120.16
    n-butyl acetate 26.3
    n-octanol 14.76
    chloroform 12.85
    n-propyl acetate 25.45
    acetic acid 65.73
    dichloromethane 7.18
    cyclohexanone 25.54
    propylene glycol 41.48
    isopropyl acetate 18.15
    DMAc 158.97
    2-ethoxyethanol 85.12
    isopentanol 20.89
    n-heptane 1.08
    ethyl formate 55.92
    1,2-dichloroethane 6.27
    n-hexanol 37.84
    2-methoxyethanol 135.21
    isobutyl acetate 14.61
    tetrachloromethane 7.32
    n-pentyl acetate 16.23
    transcutol 54.61
    n-heptanol 24.33
    ethylbenzene 2.32
    MIBK 18.69
    2-propoxyethanol 104.62
    tert-butanol 38.98
    MTBE 14.81
    2-butoxyethanol 65.85
    propionic acid 43.66
    o-xylene 2.23
    formic acid 112.79
    diethyl ether 6.88
    m-xylene 2.88
    p-xylene 3.24
    chlorobenzene 4.2
    dimethyl carbonate 37.31
    n-octane 0.56
    formamide 126.78
    cyclopentanone 83.4
    2-pentanone 26.57
    anisole 19.85
    cyclopentyl methyl ether 21.08
    gamma-butyrolactone 111.13
    1-methoxy-2-propanol 85.85
    pyridine 17.66
    3-pentanone 11.44
    furfural 95.67
    n-dodecane 0.6
    diethylene glycol 103.87
    diisopropyl ether 3.13
    tert-amyl alcohol 29.32
    acetylacetone 48.24
    n-hexadecane 0.64
    acetophenone 21.79
    methyl propionate 33.73
    isopentyl acetate 21.88
    trichloroethylene 18.35
    n-nonanol 13.46
    cyclohexanol 8.02
    benzyl alcohol 19.5
    2-ethylhexanol 18.4
    isooctanol 17.8
    dipropyl ether 11.98
    1,2-dichlorobenzene 6.43
    ethyl lactate 27.72
    propylene carbonate 48.34
    n-methylformamide 127.51
    2-pentanol 11.02
    n-pentane 0.22
    1-propoxy-2-propanol 55.1
    1-methoxy-2-propyl acetate 38.46
    2-(2-methoxypropoxy) propanol 37.53
    mesitylene 2.39
    ε-caprolactone 31.4
    p-cymene 4.65
    epichlorohydrin 74.06
    1,1,1-trichloroethane 11.4
    2-aminoethanol 71.35
    morpholine-4-carbaldehyde 85.72
    sulfolane 82.51
    2,2,4-trimethylpentane 0.48
    2-methyltetrahydrofuran 39.93
    n-hexyl acetate 19.56
    isooctane 0.53
    2-(2-butoxyethoxy)ethanol 47.96
    sec-butyl acetate 12.88
    tert-butyl acetate 22.72
    decalin 0.46
    glycerin 95.45
    diglyme 92.75
    acrylic acid 42.68
    isopropyl myristate 7.54
    n-butyric acid 54.39
    acetyl acetate 23.15
    di(2-ethylhexyl) phthalate 11.45
    ethyl propionate 21.95
    nitromethane 139.43
    1,2-diethoxyethane 16.53
    benzonitrile 16.07
    trioctyl phosphate 10.28
    1-bromopropane 2.13
    gamma-valerolactone 102.89
    n-decanol 10.38
    triethyl phosphate 13.63
    4-methyl-2-pentanol 10.29
    propionitrile 19.37
    vinylene carbonate 44.29
    1,1,2-trichlorotrifluoroethane 84.3
    DMS 14.95
    cumene 3.09
    2-octanol 10.99
    2-hexanone 24.85
    octyl acetate 12.14
    limonene 5.1
    1,2-dimethoxyethane 103.22
    ethyl orthosilicate 13.19
    tributyl phosphate 9.67
    diacetone alcohol 49.6
    N,N-dimethylaniline 16.1
    acrylonitrile 34.51
    aniline 8.08
    1,3-propanediol 79.88
    bromobenzene 2.65
    dibromomethane 3.29
    1,1,2,2-tetrachloroethane 16.44
    2-methyl-cyclohexyl acetate 15.62
    tetrabutyl urea 15.08
    diisobutyl methanol 9.3
    2-phenylethanol 27.93
    styrene 2.35
    dioctyl adipate 11.21
    dimethyl sulfate 61.58
    ethyl butyrate 20.3
    methyl lactate 49.01
    butyl lactate 19.61
    diethyl carbonate 15.49
    propanediol butyl ether 37.05
    triethyl orthoformate 16.16
    p-tert-butyltoluene 4.83
    methyl 4-tert-butylbenzoate 28.62
    morpholine 41.26
    tert-butylamine 13.35
    n-dodecanol 7.69
    dimethoxymethane 82.29
    ethylene carbonate 32.89
    cyrene 38.82
    2-ethoxyethyl acetate 22.81
    2-ethylhexyl acetate 14.76
    1,2,4-trichlorobenzene 7.33
    4-methylpyridine 16.37
    dibutyl ether 6.88
    2,6-dimethyl-4-heptanol 9.3
    DEF 34.95
    dimethyl isosorbide 59.41
    tetrachloroethylene 14.79
    eugenol 36.77
    triacetin 17.38
    span 80 26.64
    1,4-butanediol 36.16
    1,1-dichloroethane 6.5
    2-methyl-1-pentanol 18.71
    methyl formate 109.44
    2-methyl-1-butanol 17.1
    n-decane 0.88
    butyronitrile 19.29
    3,7-dimethyl-1-octanol 12.72
    1-chlorooctane 4.02
    1-chlorotetradecane 1.84
    n-nonane 0.72
    undecane 0.69
    tert-butylcyclohexane 0.8
    cyclooctane 0.16
    cyclopentanol 20.5
    tetrahydropyran 13.67
    tert-amyl methyl ether 11.13
    2,5,8-trioxanonane 68.54
    1-hexene 1.56
    2-isopropoxyethanol 48.1
    2,2,2-trifluoroethanol 54.78
    methyl butyrate 35.47

    Scent© AI

1 4

IFRA standard 51

Recommendation
No restriction
Maximum acceptable concentrations in the finished product (%)
Category 1
Products applied to the lips
 No restriction Category 7A
Rinse-off products applied to the hair with some hand contact
 No restriction
Category 2
Products applied to the axillae
 No restriction Category 7B
Leave-on products applied to the hair with some hand contact
 No restriction
Category 3
Products applied to the face/body using fingertips
 No restriction Category 8
Products with significant anogenital exposure
 No restriction
Category 4
Products related to fine fragrance
 No restriction Category 9
Products with body and hand exposure, primarily rinse off
 No restriction
Category 5A
Body lotion products applied to the body using the hands (palms), primarily leave on
 No restriction Category 10A
Household care products with mostly hand contact
 No restriction
Category 5B
Face moisturizer products applied to the face using the hands (palms), primarily leave on
 No restriction Category 10B
Household care products with mostly hand contact, including aerosol/spray products (with potential leave-on skin contact)
 No restriction
Category 5C
Hand cream products applied to the hands using the hands (palms), primarily leave on
 No restriction Category 11A
Products with intended skin contact but minimal transfer of fragrance to skin from inert substrate without UV exposure
 No restriction
Category 5D
Baby Creams, baby Oils and baby talc
 No restriction Category 11B
Products with intended skin contact but minimal transfer of fragrance to skin from inert substrate with potential UV exposure
 No restriction
Category 6
Products with oral and lip exposure
 No restriction Category 12
Products not intended for direct skin contact, minimal or insignificant transfer to skin
 No restriction