Fluorescein

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  • Identifiers

    CAS number
    2321-07-5

    Molecular formula
    C20H12O5

    SMILES
    C1=CC=C2C(=C1)C(=O)OC23C4=C(C=C(C=C4)O)OC5=C3C=CC(=C5)O

    Safety labels

    Irritant
    Irritant

  • Odor profile

    Fragrance
    Phenolic 60.06%
    Odorless 37.42%
    Sweet 35.84%
    Spicy 31.93%
    Medicinal 28.51%
    Balsamic 28.41%
    Nutty 27.35%
    Coconut 25.6%
    Vanilla 25.46%
    Bitter 23.76%

     

    Flavor
    Bitter 96.81%
    Lovage 19.3%
    Cedarleaf 19.16%
    Very strong 18.82%
    Indole 18.62%
    Sweet-like 18.42%
    Parsley 18.24%
    Nitrile 17.97%
    Ripe apricot 17.94%
    Moth ball 17.84%

     

    Odor impact est.
    Low

  • Properties

    XLogP3-AA
    3.4

    pKa est.
    8.75 (weak base)

    Molecular weight
    332.3 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra slow

    Boiling point est.
    695°C

    Melting point expt.

    • Decomposes at 554 °F. In sealed tube, melts at 597-601 °F with decomposition (NTP, 1992)
    • 315 dec °C
    • 315 °C (decomposes)
    • 315 °C

    Flash point

    • 248.78 ˚C est.

    Solubility expt.

    • Insoluble (NTP, 1992)
    • 600 mg/mL (sodium salt)
    • Slightly soluble in ethanol, diethyl ether; very soluble in acetone; soluble in pyridine, methanol
    • Insoluble in benzene, chloroform, ether. Soluble in hot alcohol or glacial acetic acid; also soluble in alkali hydroxides or carbonates with a bright green fluorescence appearing red by transmitted light.
    • In water, 50 mg/L at 20 °C
    • 2.55e-02 g/L

  • Synonyms

    • fluorescein
    • 2321-07-5
    • Solvent Yellow 94
    • Resorcinolphthalein
    • Fluoresceine
    • Yellow fluorescein
    • 3,6-Fluorandiol
    • Fluorescein acid
    • D&C Yellow No. 7
    • Japan Yellow 201
    • D and C Yellow No. 7
    • C.I. Solvent Yellow 94
    • 3',6'-Dihydroxyfluoran
    • Fluoreszein
    • Soap Yellow F
    • Hidacid fluorescein
    • Yellow 7
    • Fluorescein Red
    • D+C Yellow No. 7
    • 11712 Yellow
    • Japan Yellow No. 201
    • Zlut kysela 73
    • 9-(o-Carboxyphenyl)-6-hydroxy-3-isoxanthenone
    • 9-(o-Carboxyphenyl)-6-hydroxy-3H-xanthen-3-one
    • Spiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3-one, 3',6'-dihydroxy-
    • 3',6'-Fluorandiol
    • NSC-667256
    • CHEBI:31624
    • TPY09G7XIR
    • CI 45350:1
    • C.I. 45350:1
    • Ki201
    • NSC-759114
    • DTXSID0038887
    • DTXCID8018887
    • 3,6-Dihydroxyspiro(xanthene-9,3'-phthalide)
    • 3',6'-Dihydroxyspiro(isobenzofuran-1(3H),9'(9H)-xanthen)-3-one
    • Spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one, 3',6'-dihydroxy-
    • D & C YELLOW NO. 7 K7133
    • 3,6-Dihydroxyspiro[xanthene-9,3'-phthalide]
    • Ful Glo
    • Minims Fluoresceine
    • Fluoresceine, Minims
    • Fluorescein, Disodium
    • Colircusi Fluoresceina
    • Fluoresceina, Colircusi
    • RefChem:5834
    • Fluor I Strip A.T.
    • 3',4'-Dehydroxyfluoran
    • Disodium Salt, Fluorescein
    • Fluorescein Sodium, Minims
    • Monosodium Salt, Fluorescein
    • Dipotassium Salt, Fluorescein
    • 3',6'-dihydroxy-3H-spiro(2-benzofuran-1,9'-xanthene)-3-one
    • 2-(3-hydroxy-6-keto-xanthen-9-yl)benzoic acid
    • 3',6'-Dihydroxy-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one
    • MFCD00005050
    • D & C Yellow no. 7
    • 3',6'-dihydroxyspiro[2-benzofuran-3,9'-xanthene]-1-one
    • Fluorescein (free acid)
    • C20H12O5
    • Resorcinol phthalein
    • Fluoran, 3',6'-dihydroxy-
    • NSC 667256
    • CHEMBL1057
    • 3',6'-dihydroxy-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one
    • 3H-Xanthen-3-one, 9-(o-carboxyphenyl)-6-hydroxy-
    • NSC667256
    • Benzoic acid, o-(6-hydroxy-3-oxo-3H-xanthen-9-yl)-
    • Benzoic acid, 2-(6-hydroxy-3-oxo-3H-xanthen-9-yl)-
    • NCGC00161643-03
    • 3',6'-dihydroxyspiro[isobenzofuran-3,9'-xanthene]-1-one
    • CAS-2321-07-5
    • Zlut kysela 73 [Czech]
    • Diofluor
    • CCRIS 7076
    • Fluorescein CRS
    • HSDB 2128
    • Diresorcinolphthalein
    • EINECS 219-031-8
    • BRN 0094324
    • Fluorescite (Salt/Mix)
    • 3',6' dihydroxyfluoran
    • Fluorescein (JAN/USP)
    • FLUORESCEIN [II]
    • FLUORESCEIN [MI]
    • UNII-TPY09G7XIR
    • FLUORESCEIN [JAN]
    • FLUORESCEIN [HSDB]
    • Epitope ID:137337
    • UPCMLD-DP087
    • FLUORESCEIN [VANDF]
    • FLUORESCEIN [MART.]
    • SCHEMBL16533
    • FLUORESCEIN [USP-RS]
    • FLUORESCEIN [WHO-DD]
    • Fluorescein [USP:BAN:JAN]
    • SCHEMBL837792
    • SCHEMBL1259929
    • SCHEMBL1260701
    • SCHEMBL4941368
    • SCHEMBL29371199
    • SCHEMBL29388667
    • SCHEMBL30272223
    • UPCMLD-DP087:001
    • GNBHRKFJIUUOQI-UHFFFAOYSA-
    • Fluorescein (Solvent Yellow 94)
    • C.I. 45350 (Salt/Mix)
    • FLUORESCEIN [EP MONOGRAPH]
    • HMS2093F21
    • HMS3744C17
    • HMS5084P08
    • MOLI001003
    • Pharmakon1600-01505396
    • FLUORESCEIN [USP MONOGRAPH]
    • HY-D0251
    • Tox21_113500
    • Tox21_303508
    • BDBM50237588
    • C.I. Acid Yellow 73 (Salt/Mix)
    • EBC-26617
    • NSC759114
    • s5488
    • Spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one,3'6'-dihydroxy-
    • AKOS015903296
    • CCG-213417
    • CS-7537
    • 2321-07-5

  • Applications

    Fluorescein (CAS 2321-07-5) is a fluorescent dye widely used as a tracer and marker across multiple industries. Typical applications include fluorescence tracing for leak detection and fluid tracing in water management, utilities, and environmental assessment; fluorescent dye for inks and coatings enabling detection under UV light and quality checks during printing; fluorescent marker in analytical and imaging workflows in chemistry and biology for observation with fluorescence microscopy or spectroscopic detection; reference standards and calibration materials for fluorescence instruments such as fluorometers; used in polymer and plastics research to study diffusion, migration, and aging in resins and coatings.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 0.42
    methanol 1.12
    isopropanol 0.4
    water 0.06
    ethyl acetate 1.64
    n-propanol 0.44
    acetone 5.12
    n-butanol 0.52
    acetonitrile 2.34
    DMF 52.93
    toluene 0.55
    isobutanol 0.35
    1,4-dioxane 8.58
    methyl acetate 2.1
    THF 19.47
    2-butanone 3.39
    n-pentanol 0.68
    sec-butanol 0.29
    n-hexane 0.01
    ethylene glycol 4.04
    NMP 37.47
    cyclohexane 0.01
    DMSO 59.03
    n-butyl acetate 5.83
    n-octanol 3.95
    chloroform 0.85
    n-propyl acetate 4.11
    acetic acid 6.83
    dichloromethane 0.83
    cyclohexanone 12.25
    propylene glycol 2.42
    isopropyl acetate 2.84
    DMAc 42.84
    2-ethoxyethanol 7.9
    isopentanol 0.9
    n-heptane 0.03
    ethyl formate 3.63
    1,2-dichloroethane 1.09
    n-hexanol 1.05
    2-methoxyethanol 16.93
    isobutyl acetate 4.43
    tetrachloromethane 0.1
    n-pentyl acetate 9.48
    transcutol 71.24
    n-heptanol 2.94
    ethylbenzene 0.52
    MIBK 4.19
    2-propoxyethanol 18.94
    tert-butanol 0.95
    MTBE 0.42
    2-butoxyethanol 18.42
    propionic acid 2.99
    o-xylene 0.59
    formic acid 8.35
    diethyl ether 0.29
    m-xylene 0.64
    p-xylene 0.87
    chlorobenzene 1.44
    dimethyl carbonate 9.04
    n-octane 0.03
    formamide 15.75
    cyclopentanone 21.4
    2-pentanone 3.06
    anisole 3.97
    cyclopentyl methyl ether 2.48
    gamma-butyrolactone 25.45
    1-methoxy-2-propanol 13.87
    pyridine 7.39
    3-pentanone 1.89
    furfural 32.19
    n-dodecane 0.15
    diethylene glycol 31.82
    diisopropyl ether 0.24
    tert-amyl alcohol 0.63
    acetylacetone 15.06
    n-hexadecane 0.18
    acetophenone 10.03
    methyl propionate 2.92
    isopentyl acetate 7.42
    trichloroethylene 3.91
    n-nonanol 4.88
    cyclohexanol 0.96
    benzyl alcohol 5.88
    2-ethylhexanol 1.5
    isooctanol 3.17
    dipropyl ether 1.74
    1,2-dichlorobenzene 2.12
    ethyl lactate 10.84
    propylene carbonate 15.42
    n-methylformamide 13.72
    2-pentanol 0.33
    n-pentane 0.0
    1-propoxy-2-propanol 15.08
    1-methoxy-2-propyl acetate 17.94
    2-(2-methoxypropoxy) propanol 29.28
    mesitylene 0.54
    ε-caprolactone 11.96
    p-cymene 1.31
    epichlorohydrin 17.81
    1,1,1-trichloroethane 0.64
    2-aminoethanol 2.88
    morpholine-4-carbaldehyde 53.14
    sulfolane 54.42
    2,2,4-trimethylpentane 0.01
    2-methyltetrahydrofuran 2.6
    n-hexyl acetate 11.36
    isooctane 0.02
    2-(2-butoxyethoxy)ethanol 34.69
    sec-butyl acetate 3.22
    tert-butyl acetate 5.16
    decalin 0.04
    glycerin 16.55
    diglyme 52.22
    acrylic acid 7.26
    isopropyl myristate 7.5
    n-butyric acid 3.86
    acetyl acetate 4.33
    di(2-ethylhexyl) phthalate 11.08
    ethyl propionate 3.6
    nitromethane 21.73
    1,2-diethoxyethane 11.76
    benzonitrile 8.2
    trioctyl phosphate 8.71
    1-bromopropane 0.17
    gamma-valerolactone 55.89
    n-decanol 3.89
    triethyl phosphate 6.62
    4-methyl-2-pentanol 0.7
    propionitrile 2.23
    vinylene carbonate 15.98
    1,1,2-trichlorotrifluoroethane 32.26
    DMS 14.91
    cumene 0.59
    2-octanol 2.1
    2-hexanone 4.79
    octyl acetate 9.31
    limonene 1.14
    1,2-dimethoxyethane 18.44
    ethyl orthosilicate 5.46
    tributyl phosphate 9.58
    diacetone alcohol 12.88
    N,N-dimethylaniline 3.68
    acrylonitrile 6.69
    aniline 2.31
    1,3-propanediol 4.42
    bromobenzene 1.07
    dibromomethane 0.3
    1,1,2,2-tetrachloroethane 3.9
    2-methyl-cyclohexyl acetate 8.85
    tetrabutyl urea 15.72
    diisobutyl methanol 1.73
    2-phenylethanol 7.68
    styrene 0.63
    dioctyl adipate 13.71
    dimethyl sulfate 20.89
    ethyl butyrate 5.58
    methyl lactate 15.95
    butyl lactate 17.17
    diethyl carbonate 5.33
    propanediol butyl ether 22.09
    triethyl orthoformate 7.71
    p-tert-butyltoluene 1.22
    methyl 4-tert-butylbenzoate 18.16
    morpholine 8.31
    tert-butylamine 0.24
    n-dodecanol 3.09
    dimethoxymethane 18.15
    ethylene carbonate 12.13
    cyrene 34.8
    2-ethoxyethyl acetate 17.92
    2-ethylhexyl acetate 5.72
    1,2,4-trichlorobenzene 3.72
    4-methylpyridine 5.74
    dibutyl ether 3.86
    2,6-dimethyl-4-heptanol 1.73
    DEF 7.62
    dimethyl isosorbide 47.65
    tetrachloroethylene 1.86
    eugenol 23.73
    triacetin 23.71
    span 80 21.83
    1,4-butanediol 2.19
    1,1-dichloroethane 0.37
    2-methyl-1-pentanol 0.91
    methyl formate 12.73
    2-methyl-1-butanol 0.52
    n-decane 0.16
    butyronitrile 1.9
    3,7-dimethyl-1-octanol 4.04
    1-chlorooctane 1.16
    1-chlorotetradecane 0.84
    n-nonane 0.09
    undecane 0.15
    tert-butylcyclohexane 0.04
    cyclooctane 0.01
    cyclopentanol 1.33
    tetrahydropyran 1.61
    tert-amyl methyl ether 0.58
    2,5,8-trioxanonane 47.5
    1-hexene 0.04
    2-isopropoxyethanol 6.2
    2,2,2-trifluoroethanol 5.95
    methyl butyrate 4.96

    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