Phenolphthalein

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  • Identifiers

    CAS number
    77-09-8

    Molecular formula
    C20H14O4

    SMILES
    C1=CC=C2C(=C1)C(=O)OC2(C3=CC=C(C=C3)O)C4=CC=C(C=C4)O

    Safety labels

    Health Hazard
    Health

  • Odor profile

    Fragrance
    Phenolic 63.95%
    Sweet 46.5%
    Medicinal 36.65%
    Balsamic 35.36%
    Spicy 31.77%
    Animal 29.39%
    Aromatic 29.12%
    Bitter 28.73%
    Fruity 27.32%
    Nutty 26.85%

     

    Flavor
    Bitter 91.38%
    Lovage 20.36%
    Very strong 20.34%
    Indole 20.24%
    Moth ball 19.82%
    Cedarleaf 19.6%
    Nitrile 19.38%
    Naphthelene 19.27%
    Sweet-like 19.01%
    Tarragon 18.97%

     

    Odor impact est.
    Low

  • Properties

    XLogP3-AA
    3.6

    pKa est.
    8.11 (weak base)

    Molecular weight
    318.3 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra slow

    Boiling point est.
    576°C

    Melting point expt.

    • 496 to 504 °F (NTP, 1992)
    • 262.5 °C

    Flash point

    • 232.34 ˚C est.

    Solubility expt.

    • less than 1 mg/mL at 66 °F (NTP, 1992)
    • 400 mg/L
    • 1 g dissolves in 12 ml alcohol, in about 100 ml ether; sol in dil solutions of Alkali hydroxides and hot solutions of alkali carborates forming a red soln
    • Insoluble in benzene and petroleum ether; slightly soluble in carbon disulfide; soluble in ethyl ether, chloroform, and toluene; very soluble in ethanol, acetone, and pyrene.
    • In water, 400 mg/L @ room temperature

  • Synonyms

    • phenolphthalein
    • 77-09-8
    • Phthalimetten
    • Euchessina
    • Phthalin
    • Espotabs
    • Phenolax
    • Purgophen
    • Koprol
    • Laxogen
    • Trilax
    • Purga
    • Spulmako-lax
    • Purgen
    • Phenolphtaleine
    • Medilax
    • Colax
    • Laxin
    • FemiLax
    • Dihydroxyphthalophenone
    • 3,3-Bis(4-hydroxyphenyl)phthalide
    • 3,3-Bis(4-hydroxyphenyl)-1(3H)-isobenzofuranone
    • Fenolftalein
    • Fenolftaleina
    • Alophen
    • 1(3H)-Isobenzofuranone, 3,3-bis(4-hydroxyphenyl)-
    • 3,3-Bis(p-hydroxyphenyl)phthalide
    • Phillips Gelcaps
    • Phenophthalein
    • NCI-C55798
    • Phenolphthaleinum
    • 3,3-bis(4-hydroxyphenyl)-2-benzofuran-1-one
    • 3,3-Bis(4-hydroxyphenyl)isobenzofuran-1(3H)-one
    • alpha-Di(p-hydroxyphenyl)phthalide
    • Phenolphthalein,white
    • Feen-A-Mint Laxative Mints
    • 3,3-Bis(4-hydroxyphenyl)-2-benzofuran-1(3H)-one
    • NSC 10464
    • CCRIS 6266
    • Phthalide 3,3,-bis(p-hydroxyphenyl)-
    • DTXSID0021125
    • HSDB 4161
    • EINECS 201-004-7
    • UNII-6QK969R2IF
    • MFCD00005913
    • component of Agoral
    • 3,3-bis(4-hydroxyphenyl)-1,3-dihydro-2-benzofuran-1-one
    • BRN 0284423
    • 6QK969R2IF
    • Yellow phenolphthalein
    • CHEBI:34914
    • AI3-09081
    • NSC-10464
    • PHENOLPHTHALEIN, WHITE
    • CHEMBL63857
    • MLS000069592
    • DTXCID901125
    • Correctol
    • EC 201-004-7
    • 5-18-04-00188 (Beilstein Handbook Reference)
    • NSC10464
    • alpha-(p-Hydroxyphenyl)-alpha-(4-oxo-2,5-cyclohexadien-1-ylidene)-o-toluic acid
    • Evac-Q-Kwik
    • Evac-Q-Kit
    • Evac-U-Gen
    • component of Correctol
    • Phenolphthalein (INN)
    • NCGC00018200-07
    • SMR000059015
    • Agoral
    • Fenolftalein [Czech]
    • PHENOLPHTHALEIN [INN]
    • PHENOLPHTHALEIN (IARC)
    • PHENOLPHTHALEIN [IARC]
    • Fenolftaleina [INN-Spanish]
    • PHENOLPHTHALEIN (MART.)
    • PHENOLPHTHALEIN [MART.]
    • Phenolphtaleine [INN-French]
    • Phenolphthaleinum [INN-Latin]
    • Phthalide 3,-bis(p-hydroxyphenyl)-
    • PHENOLPHTHALEIN (EP MONOGRAPH)
    • PHENOLPHTHALEIN [EP MONOGRAPH]
    • CAS-77-09-8
    • WLN: T56 BVO DHJ D- D-/R DQ 2
    • Phenolphthalein (0.04% Solution in Ethanol)
    • 1(3H)-Isobenzofuranone,3-bis(4-hydroxyphenyl)-
    • phenolphtalein
    • Phenolphthalein [USP:INN:BAN]
    • FGT
    • white phenolphthalein
    • Doxan (Salt/Mix)
    • Agoral (Salt/Mix)
    • Modane (TN)
    • Phenolphthalein White
    • Laxcaps (Salt/Mix)
    • Phenolphthalein,yellow
    • PHENPOLPHTHALEIN
    • Phenolphthalein solution
    • Spectrum_001077
    • Opera_ID_1337
    • Spectrum2_001279
    • Spectrum3_000888
    • Spectrum4_000982
    • Spectrum5_001268
    • Modane Plus (Salt/Mix)
    • 3,3-bis(4-hydroxyphenyl)isobenzofuran-1-one
    • Phenolphthalein ACS reagent
    • Phenolphthalein solution R1
    • cid_4764
    • PHENOLPHTHALEIN [MI]
    • Phenolphthalein, ACS reagent
    • SCHEMBL27670
    • BSPBio_002518
    • KBioGR_001383
    • KBioSS_001557
    • Phenolphthalein, pH indicator
    • MLS001148397
    • BIDD:ER0202
    • DivK1c_000929
    • PHENOLPHTHALEIN [HSDB]
    • SPECTRUM1500480
    • Phenolphthalein Paper, DAB 6
    • SPBio_001278
    • PHENOLPHTHALEIN [VANDF]
    • 3,3-bis(4-hydroxyphenyl)-3-hydroisobenzofuran-1-one
    • PHENPOLPHTHALEIN [VANDF]
    • PHENOLPHTHALEIN [WHO-DD]
    • BCBcMAP01_000174

  • Applications

    Phenolphthalein (CAS 77-09-8) is a color-changing acid-base indicator widely used in analytical chemistry for endpoint determination in titrations and in teaching laboratories; it also serves in water quality work as an indicator for pH and alkalinity control. It functions as an intermediate in the synthesis of triphenylmethane dyes and related colorants used in specialty inks and coatings. Historically, phenolphthalein has been used in some pharmaceutical laxatives, although its use today is limited by safety considerations and regulatory restrictions. In addition, it may appear as a dye precursor or indicator in certain analytical reagents and research formulations, subject to local regulations.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 1.52
    methanol 2.88
    isopropanol 0.86
    water 0.18
    ethyl acetate 1.31
    n-propanol 1.14
    acetone 5.67
    n-butanol 1.03
    acetonitrile 2.29
    DMF 73.81
    toluene 1.16
    isobutanol 0.75
    1,4-dioxane 9.98
    methyl acetate 1.62
    THF 39.33
    2-butanone 3.76
    n-pentanol 1.6
    sec-butanol 0.85
    n-hexane 0.01
    ethylene glycol 5.32
    NMP 24.28
    cyclohexane 0.02
    DMSO 48.74
    n-butyl acetate 5.05
    n-octanol 6.15
    chloroform 2.73
    n-propyl acetate 3.37
    acetic acid 7.9
    dichloromethane 2.58
    cyclohexanone 12.16
    propylene glycol 4.02
    isopropyl acetate 3.13
    DMAc 56.85
    2-ethoxyethanol 11.37
    isopentanol 1.72
    n-heptane 0.06
    ethyl formate 2.85
    1,2-dichloroethane 2.36
    n-hexanol 2.54
    2-methoxyethanol 22.24
    isobutyl acetate 4.06
    tetrachloromethane 0.24
    n-pentyl acetate 10.28
    transcutol 53.63
    n-heptanol 6.42
    ethylbenzene 1.19
    MIBK 5.64
    2-propoxyethanol 21.15
    tert-butanol 2.45
    MTBE 1.18
    2-butoxyethanol 22.15
    propionic acid 2.87
    o-xylene 1.2
    formic acid 9.86
    diethyl ether 0.63
    m-xylene 1.32
    p-xylene 1.59
    chlorobenzene 2.2
    dimethyl carbonate 7.73
    n-octane 0.09
    formamide 23.48
    cyclopentanone 23.24
    2-pentanone 3.25
    anisole 7.11
    cyclopentyl methyl ether 3.71
    gamma-butyrolactone 21.98
    1-methoxy-2-propanol 17.95
    pyridine 10.68
    3-pentanone 2.09
    furfural 25.71
    n-dodecane 0.28
    diethylene glycol 28.08
    diisopropyl ether 0.53
    tert-amyl alcohol 1.9
    acetylacetone 13.82
    n-hexadecane 0.33
    acetophenone 12.48
    methyl propionate 2.42
    isopentyl acetate 7.96
    trichloroethylene 8.33
    n-nonanol 7.55
    cyclohexanol 1.53
    benzyl alcohol 8.74
    2-ethylhexanol 2.9
    isooctanol 6.64
    dipropyl ether 2.7
    1,2-dichlorobenzene 3.59
    ethyl lactate 9.27
    propylene carbonate 12.14
    n-methylformamide 12.52
    2-pentanol 0.73
    n-pentane 0.01
    1-propoxy-2-propanol 15.95
    1-methoxy-2-propyl acetate 16.6
    2-(2-methoxypropoxy) propanol 28.82
    mesitylene 1.09
    ε-caprolactone 9.39
    p-cymene 2.42
    epichlorohydrin 22.72
    1,1,1-trichloroethane 1.3
    2-aminoethanol 5.5
    morpholine-4-carbaldehyde 39.96
    sulfolane 40.76
    2,2,4-trimethylpentane 0.05
    2-methyltetrahydrofuran 4.72
    n-hexyl acetate 11.85
    isooctane 0.05
    2-(2-butoxyethoxy)ethanol 33.01
    sec-butyl acetate 3.24
    tert-butyl acetate 7.49
    decalin 0.1
    glycerin 19.99
    diglyme 50.82
    acrylic acid 6.51
    isopropyl myristate 7.95
    n-butyric acid 3.85
    acetyl acetate 3.87
    di(2-ethylhexyl) phthalate 11.61
    ethyl propionate 3.11
    nitromethane 19.13
    1,2-diethoxyethane 13.36
    benzonitrile 9.24
    trioctyl phosphate 8.86
    1-bromopropane 0.41
    gamma-valerolactone 41.62
    n-decanol 6.04
    triethyl phosphate 7.23
    4-methyl-2-pentanol 1.53
    propionitrile 2.43
    vinylene carbonate 12.41
    1,1,2-trichlorotrifluoroethane 28.44
    DMS 13.89
    cumene 1.35
    2-octanol 4.49
    2-hexanone 5.11
    octyl acetate 9.45
    limonene 2.01
    1,2-dimethoxyethane 22.55
    ethyl orthosilicate 7.04
    tributyl phosphate 8.75
    diacetone alcohol 16.06
    N,N-dimethylaniline 6.37
    acrylonitrile 6.55
    aniline 3.54
    1,3-propanediol 6.68
    bromobenzene 1.83
    dibromomethane 0.89
    1,1,2,2-tetrachloroethane 7.0
    2-methyl-cyclohexyl acetate 9.94
    tetrabutyl urea 14.29
    diisobutyl methanol 3.15
    2-phenylethanol 11.46
    styrene 1.45
    dioctyl adipate 13.3
    dimethyl sulfate 18.9
    ethyl butyrate 5.3
    methyl lactate 12.95
    butyl lactate 14.89
    diethyl carbonate 5.43
    propanediol butyl ether 20.53
    triethyl orthoformate 8.1
    p-tert-butyltoluene 2.24
    methyl 4-tert-butylbenzoate 21.77
    morpholine 10.16
    tert-butylamine 0.74
    n-dodecanol 4.66
    dimethoxymethane 21.41
    ethylene carbonate 8.64
    cyrene 29.9
    2-ethoxyethyl acetate 17.08
    2-ethylhexyl acetate 6.08
    1,2,4-trichlorobenzene 5.45
    4-methylpyridine 6.19
    dibutyl ether 5.11
    2,6-dimethyl-4-heptanol 3.15
    DEF 7.31
    dimethyl isosorbide 44.22
    tetrachloroethylene 3.9
    eugenol 26.91
    triacetin 20.64
    span 80 20.89
    1,4-butanediol 3.36
    1,1-dichloroethane 0.81
    2-methyl-1-pentanol 2.16
    methyl formate 10.36
    2-methyl-1-butanol 1.2
    n-decane 0.36
    butyronitrile 2.34
    3,7-dimethyl-1-octanol 5.89
    1-chlorooctane 2.16
    1-chlorotetradecane 1.34
    n-nonane 0.21
    undecane 0.31
    tert-butylcyclohexane 0.1
    cyclooctane 0.02
    cyclopentanol 2.21
    tetrahydropyran 2.83
    tert-amyl methyl ether 1.58
    2,5,8-trioxanonane 48.11
    1-hexene 0.12
    2-isopropoxyethanol 8.86
    2,2,2-trifluoroethanol 5.67
    methyl butyrate 4.22

    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