Phthalic acid

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  • Identifiers

    CAS number
    88-99-3

    Molecular formula
    C8H6O4

    SMILES
    C1=CC=C(C(=C1)C(=O)O)C(=O)O

    Safety labels

    Corrosive
    Corrosive

    Irritant
    Irritant

  • Odor profile

    Fragrance
    Odorless 56.84%
    Sour 43.53%
    Phenolic 41.77%
    Balsamic 35.82%
    Burnt 32.43%
    Nutty 31.6%
    Aromatic 26.23%
    Bitter 23.44%
    Sharp 23.36%
    Clean 22.19%

     

    Flavor
    Odorless 57.43%
    Nutty 51.09%
    Phenolic 46.91%
    Sour 41.88%
    Faint 39.99%
    Mild 39.11%
    Balsam 32.61%
    Very mild 29.14%
    Balsamic 27.56%
    Urine 26.16%

     

    Odor impact est.
    Low

  • Properties

    XLogP3-AA
    0.7

    pKa est.
    5.54 (weak acid)

    Molecular weight
    166.13 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra slow

    Melting point expt.

    • 410 to 412 °F (decomposes) (NTP, 1992)
    • 230 dec °C
    • Decomposes at 230 °C
    • Melting point: ca. 210 °C, converted into phthalic anhydride with the elimination of water.
    • Triple point temperature and pressure = 464.15 K (estimated to be equal to the melting point), 7.8183X10+3 Pa
    • Melting point = 464.15 K (determined in a sealed tube)
    • 205 - 230 °C
    • 410-412 °F

    Boiling point

    • Decomposes (NTP, 1992)
    • Decomposes
    • Boiling point = 598.00 K (Based on predicted value for phthalic acid by Meissner's method with a suitable adjustment for isomerism based on similar compound relationships.)
    • decomposes

    Flash point

    • 187.83 ˚C est.
    • 334 °F (NTP, 1992)
    • 334 °F (168 °C) (Closed cup)
    • 168 °C c.c.
    • 334 °F

    Solubility expt.

    • less than 1 mg/mL at 68 °F (NTP, 1992)
    • 7010 mg/L (at 25 °C)
    • Soluble in alcohol; sparingly soluble in ether
    • 1 g dissolves in 160 ml water, 10 ml alc, 205 ml ether, 5.3 ml methanol; practically insol in chloroform
    • In water, 6,965 mg/L at 25 °C
    • 7.01 mg/mL at 25 °C
    • Solubility in water, g/100ml at 25 °C: 0.625 (poor)

  • Synonyms

    • phthalic acid
    • 88-99-3
    • 1,2-benzenedicarboxylic acid
    • o-phthalic acid
    • Pathalic acid
    • benzene-1,2-dicarboxylic acid
    • o-dicarboxybenzene
    • o-benzenedicarboxylic acid
    • Acide phtalique
    • Kyselina ftalova
    • ortho-phthalic acid
    • Sunftal 20
    • MFCD00002467
    • CCRIS 1446
    • HSDB 1339
    • Orthophthalic acid
    • NSC 5348
    • EINECS 201-873-2
    • UNII-6O7F7IX66E
    • BRN 0608199
    • PhthalicAcid-13C2
    • 6O7F7IX66E
    • o-Carboxybenzoic acid
    • DTXSID8021484
    • CHEBI:29069
    • AI3-02409
    • NSC-5348
    • CHEMBL1045
    • DTXCID901484
    • EC 201-873-2
    • 4-09-00-03167 (Beilstein Handbook Reference)
    • Phthalic-13C Acid
    • PHTHALICACID
    • 254110-94-6
    • Copper(ii)phthalate
    • Phthalic Acid-13C2
    • Benzene-1,2-dicarboxylic Acid (Phthalic Acid)
    • PHTHALIC ACID (USP-RS)
    • PHTHALIC ACID [USP-RS]
    • Acide phtalique [French]
    • Kyselina ftalova [Czech]
    • Phthalic Acid (Phenyl-13C6, D4)
    • PHTHALIC ACID (USP IMPURITY)
    • PHTHALIC ACID [USP IMPURITY]
    • FLUORESCEIN IMPURITY B (EP IMPURITY)
    • FLUORESCEIN IMPURITY B [EP IMPURITY]
    • FLUORESCEIN SODIUM IMPURITY B (EP IMPURITY)
    • FLUORESCEIN SODIUM IMPURITY B [EP IMPURITY]
    • Alizarinate
    • Naphthalinate
    • Phthalinate
    • Alizarinic acid
    • Phthalinic acid
    • Naphthalinic acid
    • o-Carboxybenzoate
    • 4kww
    • folpet TP2
    • phthalsäure
    • Benzene-1,2-dicarboxylic Acid; Phthalic acid; Fluorescein Sodium Imp. B (EP); Fluorescein Imp. B (EP); Fluorescein Sodium Impurity B; Fluorescein Impurity B
    • o-Benzenedicarboxylate
    • Phthalic acid, ~99%
    • WLN: QVR BVQ
    • Phthalic acid (Standard)
    • Phthalate standard for IC
    • Phthalic acid, 99.5%
    • benzoic acid, 2-carboxy-
    • bmse000391
    • PHTHALIC ACID [MI]
    • Picoxystrobin metabolite 15
    • SCHEMBL1808
    • 1,2-benzendicarboxylic acid
    • PHTHALIC ACID [HSDB]
    • MLS002152931
    • HY-I0508R
    • NSC5348
    • HMS3039E17
    • HMS3604J03
    • Phthalic acid, analytical standard
    • BCP15370
    • EKA11094
    • HY-I0508
    • STR06656
    • VCA83883
    • Phthalic acid, reagent grade, 98%
    • Tox21_200915
    • BDBM50080272
    • MSK000852
    • s6215
    • STL168879
    • AKOS000118898
    • DB02746
    • FP27023
    • CAS-88-99-3
    • NCGC00090869-01
    • NCGC00090869-02
    • NCGC00258469-01
    • Phthalic acid, ACS reagent, >=99.5%
    • AC-14464
    • BP-21159
    • DA-48993
    • DA-76837
    • SMR001224528
    • CS-0009407
    • NS00008610
    • P0287
    • Phthalic acid, SAJ first grade, >=99.0%
    • 1,2-Benzenedicarboxylic acid;M 2;NSC 5348
    • EN300-17992
    • Phthalic acid, SAJ special grade, >=99.0%
    • C01606
    • Phthalic acid, Vetec(TM) reagent grade, 98%
    • Phthalic acid, puriss. p.a., >=99.5% (T)
    • AB-131/40237186
    • Q423876
    • Z57127456
    • F3110-2832
    • Phthalic acid, European Pharmacopoeia (EP) Reference Standard
    • Phthalic acid, United States Pharmacopeia (USP) Reference Standard
    • 201-873-2
    • InChI=1/C8H6O4/c9-7(10)5-3-1-2-4-6(5)8(11)12/h1-4H,(H,9,10)(H,11,12

  • Applications

    Phthalic acid (CAS 88-99-3) is primarily used as a feedstock for the production of phthalic anhydride, a key intermediate in manufacturing alkyd resins and unsaturated polyesters for coatings and paints. It also serves as a starting material for the synthesis of phthalate plasticizers, which are widely used to soften polymers such as PVC and to formulate coatings and adhesives. In addition, phthalic acid is employed as a building block in the manufacture of specialty resins and crosslinking agents for industrial coatings and inks. Depending on local regulations and formulation limits, its applications may vary.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 56.34
    methanol 84.56
    isopropanol 39.47
    water 5.57
    ethyl acetate 13.41
    n-propanol 32.54
    acetone 89.6
    n-butanol 27.64
    acetonitrile 58.22
    DMF 1084.17
    toluene 4.05
    isobutanol 18.48
    1,4-dioxane 102.77
    methyl acetate 31.4
    THF 164.61
    2-butanone 49.76
    n-pentanol 20.84
    sec-butanol 28.34
    n-hexane 1.98
    ethylene glycol 57.53
    NMP 148.16
    cyclohexane 0.69
    DMSO 1073.17
    n-butyl acetate 11.59
    n-octanol 29.41
    chloroform 16.47
    n-propyl acetate 5.74
    acetic acid 9.61
    dichloromethane 24.27
    cyclohexanone 27.38
    propylene glycol 18.28
    isopropyl acetate 8.95
    DMAc 413.36
    2-ethoxyethanol 66.36
    isopentanol 19.89
    n-heptane 2.31
    ethyl formate 13.93
    1,2-dichloroethane 45.31
    n-hexanol 28.2
    2-methoxyethanol 151.17
    isobutyl acetate 1.57
    tetrachloromethane 6.38
    n-pentyl acetate 13.53
    transcutol 37.89
    n-heptanol 28.73
    ethylbenzene 5.38
    MIBK 17.1
    2-propoxyethanol 66.49
    tert-butanol 58.34
    MTBE 34.68
    2-butoxyethanol 46.36
    propionic acid 6.98
    o-xylene 7.49
    formic acid 25.18
    diethyl ether 33.75
    m-xylene 5.87
    p-xylene 5.3
    chlorobenzene 5.02
    dimethyl carbonate 25.88
    n-octane 2.3
    formamide 73.9
    cyclopentanone 75.09
    2-pentanone 33.35
    anisole 16.16
    cyclopentyl methyl ether 33.24
    gamma-butyrolactone 51.88
    1-methoxy-2-propanol 83.58
    pyridine 28.88
    3-pentanone 29.35
    furfural 37.8
    n-dodecane 2.33
    diethylene glycol 78.02
    diisopropyl ether 6.99
    tert-amyl alcohol 40.43
    acetylacetone 31.66
    n-hexadecane 2.64
    acetophenone 13.49
    methyl propionate 27.04
    isopentyl acetate 9.37
    trichloroethylene 36.67
    n-nonanol 26.8
    cyclohexanol 13.7
    benzyl alcohol 12.66
    2-ethylhexanol 12.48
    isooctanol 18.12
    dipropyl ether 16.06
    1,2-dichlorobenzene 7.79
    ethyl lactate 7.73
    propylene carbonate 11.22
    n-methylformamide 147.63
    2-pentanol 19.23
    n-pentane 1.53
    1-propoxy-2-propanol 33.18
    1-methoxy-2-propyl acetate 16.32
    2-(2-methoxypropoxy) propanol 25.71
    mesitylene 5.3
    ε-caprolactone 14.84
    p-cymene 5.78
    epichlorohydrin 94.78
    1,1,1-trichloroethane 13.22
    2-aminoethanol 52.62
    morpholine-4-carbaldehyde 120.67
    sulfolane 118.08
    2,2,4-trimethylpentane 1.27
    2-methyltetrahydrofuran 45.86
    n-hexyl acetate 19.19
    isooctane 1.01
    2-(2-butoxyethoxy)ethanol 37.85
    sec-butyl acetate 3.32
    tert-butyl acetate 15.02
    decalin 1.22
    glycerin 40.9
    diglyme 74.92
    acrylic acid 7.45
    isopropyl myristate 10.4
    n-butyric acid 9.31
    acetyl acetate 5.43
    di(2-ethylhexyl) phthalate 8.49
    ethyl propionate 8.37
    nitromethane 59.25
    1,2-diethoxyethane 18.85
    benzonitrile 10.26
    trioctyl phosphate 11.03
    1-bromopropane 17.15
    gamma-valerolactone 56.46
    n-decanol 20.81
    triethyl phosphate 8.58
    4-methyl-2-pentanol 11.34
    propionitrile 27.31
    vinylene carbonate 8.92
    1,1,2-trichlorotrifluoroethane 44.29
    DMS 11.85
    cumene 4.6
    2-octanol 19.77
    2-hexanone 13.85
    octyl acetate 15.15
    limonene 7.49
    1,2-dimethoxyethane 111.7
    ethyl orthosilicate 8.27
    tributyl phosphate 7.57
    diacetone alcohol 34.01
    N,N-dimethylaniline 20.04
    acrylonitrile 40.5
    aniline 10.68
    1,3-propanediol 52.29
    bromobenzene 4.5
    dibromomethane 16.34
    1,1,2,2-tetrachloroethane 41.65
    2-methyl-cyclohexyl acetate 7.32
    tetrabutyl urea 16.6
    diisobutyl methanol 9.63
    2-phenylethanol 16.92
    styrene 4.88
    dioctyl adipate 10.4
    dimethyl sulfate 76.13
    ethyl butyrate 7.61
    methyl lactate 22.57
    butyl lactate 11.3
    diethyl carbonate 5.67
    propanediol butyl ether 26.29
    triethyl orthoformate 7.32
    p-tert-butyltoluene 6.39
    methyl 4-tert-butylbenzoate 24.73
    morpholine 104.65
    tert-butylamine 29.02
    n-dodecanol 15.7
    dimethoxymethane 223.4
    ethylene carbonate 7.74
    cyrene 21.3
    2-ethoxyethyl acetate 15.31
    2-ethylhexyl acetate 7.54
    1,2,4-trichlorobenzene 8.31
    4-methylpyridine 24.2
    dibutyl ether 13.56
    2,6-dimethyl-4-heptanol 9.63
    DEF 73.43
    dimethyl isosorbide 37.53
    tetrachloroethylene 30.39
    eugenol 25.08
    triacetin 10.09
    span 80 18.44
    1,4-butanediol 25.94
    1,1-dichloroethane 16.6
    2-methyl-1-pentanol 14.43
    methyl formate 76.24
    2-methyl-1-butanol 19.23
    n-decane 3.63
    butyronitrile 21.09
    3,7-dimethyl-1-octanol 15.23
    1-chlorooctane 14.0
    1-chlorotetradecane 6.26
    n-nonane 3.22
    undecane 2.87
    tert-butylcyclohexane 1.43
    cyclooctane 0.59
    cyclopentanol 24.14
    tetrahydropyran 32.34
    tert-amyl methyl ether 29.94
    2,5,8-trioxanonane 54.98
    1-hexene 6.93
    2-isopropoxyethanol 27.4
    2,2,2-trifluoroethanol 12.41
    methyl butyrate 10.81

    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