Potassium hydrogen phthalate

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  • Identifiers

    CAS number
    877-24-7

    Molecular formula
    C8H5KO4

    SMILES
    C1=CC=C(C(=C1)C(=O)O)C(=O)[O-].[K+]

    Safety labels

    Corrosive
    Corrosive

  • Odor profile

    Fragrance
    Odorless 55.94%
    Balsamic 37.82%
    Sour 36.61%
    Phenolic 36.44%
    Nutty 29.15%
    Burnt 28.26%
    Sweet 27.05%
    Aromatic 25.49%
    Bitter 25.37%
    Honey 24.47%

     

    Flavor
    Odorless 53.02%
    Nutty 45.06%
    Phenolic 40.01%
    Mild 35.92%
    Faint 34.53%
    Sour 30.43%
    Balsam 29.67%
    Very mild 28.35%
    Honey 25.12%
    Balsamic 25.03%

     

    Odor impact est.
    Low

  • Properties

    pKa est.
    3.41 (weak acid)

    Molecular weight
    204.22 g/mol

    Flash point

    • 166.24 ˚C est.

  • Synonyms

    • Potassium hydrogen phthalate
    • 877-24-7
    • Potassium biphthalate
    • Potassium acid phthalate
    • Hydrogen potassium phthalate
    • 1,2-Benzenedicarboxylic acid, monopotassium salt
    • GG9121M623
    • RefChem:867719
    • 212-889-4
    • Monopotassium phthalate
    • Potassium phthalate monobasic
    • Phthalic acid monopotassium salt
    • potassium;2-carboxybenzoate
    • POTASSIUM 2-CARBOXYBENZOATE
    • MFCD00013070
    • KHP
    • DTXSID0042167
    • Potassium hydrogen phthalate, 0.2 M
    • Phthalic acid monopotassium
    • 1,2-Benzenedicarboxylic acid, potassium salt (1:1)
    • 29801-94-3
    • Phthalic acid, monopotassium salt
    • SCHEMBL183233
    • EINECS 212-889-4
    • AI3-51765
    • UNII-GG9121M623
    • potassium hydrogen-phthalate
    • C8H5KO4
    • SCHEMBL183234
    • orb2942870
    • Potassium phthalate monobasicKHP
    • CHEMBL3187152
    • DTXCID8022167
    • SCHEMBL29397108
    • POTASSIUM BIPHTHALATE [MI]
    • HY-Y0037
    • Tox21_301351
    • AKOS015838971
    • AKOS024318879
    • FP43259
    • MSK157941K-1000W
    • NCGC00255874-01
    • AS-80977
    • CAS-877-24-7
    • DB-255984
    • CS-0008329
    • P0309
    • ST50406635
    • benzene-1,2-dicarboxylic acid, potassium salt
    • EN300-78138
    • Potassium hydrogen phthalate, primary standard
    • F492528
    • Q424699
    • F1905-7235
    • Potassium hydrogen phthalate Solution in Water, 1000ug/mL
    • 877-24-7

  • Applications

    Potassium hydrogen phthalate (CAS number: 877-24-7) serves as a primary standard in analytical chemistry, most notably for standardizing base solutions (e.g., NaOH) in acid–base titrations. Its high purity, stability, and low hygroscopicity make it a reliable reference material for gravimetric determinations and method validation in QC workflows. It is also used to prepare standardized buffer solutions for calibrating pH meters (typically yielding buffers around pH 4–5). In educational and research laboratories it supports routine titration experiments and method development. In pharmaceutical and chemical manufacturing, it functions as a reference standard for quality control of analytical methods and instrument performance.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 227.31
    methanol 396.35
    isopropanol 146.35
    water 16.98
    ethyl acetate 62.62
    n-propanol 142.22
    acetone 293.14
    n-butanol 118.19
    acetonitrile 173.04
    DMF 2787.02
    toluene 27.24
    isobutanol 79.02
    1,4-dioxane 400.95
    methyl acetate 141.46
    THF 531.81
    2-butanone 183.36
    n-pentanol 95.27
    sec-butanol 127.09
    n-hexane 4.96
    ethylene glycol 273.49
    NMP 284.72
    cyclohexane 2.68
    DMSO 2151.26
    n-butyl acetate 37.64
    n-octanol 113.63
    chloroform 62.83
    n-propyl acetate 35.23
    acetic acid 45.56
    dichloromethane 106.41
    cyclohexanone 81.04
    propylene glycol 85.88
    isopropyl acetate 38.84
    DMAc 998.54
    2-ethoxyethanol 327.8
    isopentanol 87.42
    n-heptane 5.12
    ethyl formate 59.58
    1,2-dichloroethane 176.17
    n-hexanol 103.21
    2-methoxyethanol 653.82
    isobutyl acetate 11.24
    tetrachloromethane 17.69
    n-pentyl acetate 53.25
    transcutol 276.95
    n-heptanol 94.03
    ethylbenzene 26.05
    MIBK 65.75
    2-propoxyethanol 250.17
    tert-butanol 202.56
    MTBE 123.84
    2-butoxyethanol 183.75
    propionic acid 35.67
    o-xylene 33.74
    formic acid 120.32
    diethyl ether 130.96
    m-xylene 28.82
    p-xylene 24.3
    chlorobenzene 26.38
    dimethyl carbonate 120.62
    n-octane 5.83
    formamide 312.18
    cyclopentanone 198.07
    2-pentanone 123.75
    anisole 88.16
    cyclopentyl methyl ether 119.86
    gamma-butyrolactone 153.13
    1-methoxy-2-propanol 347.72
    pyridine 114.26
    3-pentanone 102.07
    furfural 136.0
    n-dodecane 7.43
    diethylene glycol 308.49
    diisopropyl ether 25.95
    tert-amyl alcohol 161.66
    acetylacetone 125.95
    n-hexadecane 8.35
    acetophenone 59.54
    methyl propionate 123.94
    isopentyl acetate 29.65
    trichloroethylene 151.17
    n-nonanol 98.68
    cyclohexanol 52.99
    benzyl alcohol 66.92
    2-ethylhexanol 41.92
    isooctanol 58.62
    dipropyl ether 48.07
    1,2-dichlorobenzene 32.8
    ethyl lactate 37.66
    propylene carbonate 35.3
    n-methylformamide 556.87
    2-pentanol 82.02
    n-pentane 5.06
    1-propoxy-2-propanol 118.16
    1-methoxy-2-propyl acetate 57.74
    2-(2-methoxypropoxy) propanol 108.57
    mesitylene 21.74
    ε-caprolactone 49.95
    p-cymene 18.08
    epichlorohydrin 391.74
    1,1,1-trichloroethane 52.54
    2-aminoethanol 227.23
    morpholine-4-carbaldehyde 424.43
    sulfolane 261.25
    2,2,4-trimethylpentane 3.62
    2-methyltetrahydrofuran 141.65
    n-hexyl acetate 80.54
    isooctane 2.98
    2-(2-butoxyethoxy)ethanol 190.82
    sec-butyl acetate 19.97
    tert-butyl acetate 59.04
    decalin 3.77
    glycerin 165.39
    diglyme 332.08
    acrylic acid 37.73
    isopropyl myristate 38.13
    n-butyric acid 38.59
    acetyl acetate 26.47
    di(2-ethylhexyl) phthalate 28.06
    ethyl propionate 43.3
    nitromethane 262.42
    1,2-diethoxyethane 91.45
    benzonitrile 47.78
    trioctyl phosphate 34.73
    1-bromopropane 64.91
    gamma-valerolactone 195.47
    n-decanol 77.0
    triethyl phosphate 24.17
    4-methyl-2-pentanol 44.24
    propionitrile 107.1
    vinylene carbonate 33.74
    1,1,2-trichlorotrifluoroethane 165.73
    DMS 56.0
    cumene 19.37
    2-octanol 71.1
    2-hexanone 66.54
    octyl acetate 58.95
    limonene 21.57
    1,2-dimethoxyethane 446.07
    ethyl orthosilicate 23.46
    tributyl phosphate 26.11
    diacetone alcohol 129.12
    N,N-dimethylaniline 75.5
    acrylonitrile 170.99
    aniline 52.77
    1,3-propanediol 226.43
    bromobenzene 24.13
    dibromomethane 63.61
    1,1,2,2-tetrachloroethane 148.04
    2-methyl-cyclohexyl acetate 23.37
    tetrabutyl urea 51.85
    diisobutyl methanol 26.73
    2-phenylethanol 71.1
    styrene 27.32
    dioctyl adipate 38.33
    dimethyl sulfate 245.51
    ethyl butyrate 26.03
    methyl lactate 94.22
    butyl lactate 42.38
    diethyl carbonate 20.06
    propanediol butyl ether 127.74
    triethyl orthoformate 22.37
    p-tert-butyltoluene 19.58
    methyl 4-tert-butylbenzoate 80.18
    morpholine 387.15
    tert-butylamine 87.13
    n-dodecanol 56.08
    dimethoxymethane 786.22
    ethylene carbonate 27.88
    cyrene 72.95
    2-ethoxyethyl acetate 68.65
    2-ethylhexyl acetate 22.82
    1,2,4-trichlorobenzene 34.2
    4-methylpyridine 94.48
    dibutyl ether 52.13
    2,6-dimethyl-4-heptanol 26.73
    DEF 242.22
    dimethyl isosorbide 127.98
    tetrachloroethylene 109.65
    eugenol 99.39
    triacetin 45.07
    span 80 73.9
    1,4-butanediol 122.23
    1,1-dichloroethane 71.81
    2-methyl-1-pentanol 65.42
    methyl formate 338.81
    2-methyl-1-butanol 84.38
    n-decane 11.1
    butyronitrile 76.27
    3,7-dimethyl-1-octanol 57.47
    1-chlorooctane 49.8
    1-chlorotetradecane 21.8
    n-nonane 9.47
    undecane 9.14
    tert-butylcyclohexane 4.28
    cyclooctane 2.08
    cyclopentanol 77.16
    tetrahydropyran 123.05
    tert-amyl methyl ether 111.95
    2,5,8-trioxanonane 228.91
    1-hexene 23.68
    2-isopropoxyethanol 147.68
    2,2,2-trifluoroethanol 44.68
    methyl butyrate 51.59

    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