Isobutyric acid

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  • Identifiers

    CAS number
    79-31-2

    Molecular formula
    C4H8O2

    SMILES
    CC(C)C(=O)O

    Safety labels

    Irritant
    Irritant

    Retention indicies (RI)

    • Carbowax: 1555.86

  • Odor profile

    Fruity 84.83%
    Cheesy 78.98%
    Sour 63.17%
    Dairy 49.5%
    Pungent 48.92%
    Sharp 44.88%
    Sweaty 44.36%
    Buttery 43.92%
    Milky 36.26%
    Creamy 33.43%

    Scent© AI

    Odor threshold

    • Odor Threshold Low: 8.0 [mmHg]. [Merck Index] Odor threshold from CHEMINFO
    • Odor detection threshold in water: 8.1 ppm.
    • Aroma threshold values: Detection: 10 ppb to 9.5 ppm.
    • It has a stench odor.

  • Properties

    XLogP3-AA
    0.8

    pKa est.
    7.76 (neutral)

    Molecular weight
    88.11 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Very fast

    Melting point expt.

    • -51 °F (USCG, 1999)
    • -46 °C
    • -47 °C

    Boiling point

    • 309 °F at 760 mmHg (USCG, 1999)
    • 154.4 °C
    • 152-155 °C at 760 mm Hg
    • 152-155 °C

    Flash point est.
    59.21 ˚C

    Flash point expt.

    • 132 °F (NFPA, 2010)
    • 77 °C
    • 170 °F OPEN CUP
    • 132 °F (56 °C) (closed cup)
    • 56 °C c.c.

    Solubility expt.

    • 167000 mg/L (at 20 °C)
    • Slightly soluble in carbon tetrachloride
    • Sol in 6 parts of water; miscible with alcohol, chloroform, and ether.
    • In water, 1.67X10+5 mg/L at 20 °C
    • 167 mg/mL at 20 °C
    • Solubility in water, g/100ml at 20 °C: 20
    • miscible with alcohol, most fixed oils, glycerine and propylene glycol; insoluble in water

  • Synonyms

    • ISOBUTYRIC ACID
    • 2-Methylpropanoic acid
    • 79-31-2
    • Isobutanoic acid
    • 2-Methylpropionic acid
    • Dimethylacetic acid
    • Iso-butyric acid
    • Isopropylformic acid
    • Propanoic acid, 2-methyl-
    • Isobutyrate
    • Cenex RP b2
    • alpha-Methylpropanoic acid
    • alpha-Methylpropionic acid
    • Acetic acid, dimethyl-
    • Propionic acid, 2-methyl-
    • Isobutanoate
    • Isobutyric acid (natural)
    • Tenox IBP-2
    • 2-METHYL-PROPIONIC ACID
    • Kyselina isomaselna
    • Isobuttersaeure
    • iso-C3H7COOH
    • i-Butyric acid
    • Caswell No. 503AA
    • FEMA No. 2222
    • Tenox IBP-2 Grain Pr.
    • alpha-isobutyric acid
    • Kyselina isomaselna [Czech]
    • NSC 62780
    • 2,2-dimethylacetic acid
    • HSDB 5228
    • Methylpropanoic acid, 2-
    • EINECS 201-195-7
    • .alpha.-Methylpropanoic acid
    • methylpropanoic acid
    • MFCD00002658
    • EPA Pesticide Chemical Code 101502
    • UNII-8LL210O1U0
    • BRN 0635770
    • 2-Methylpropionsaeure
    • DTXSID4021636
    • CHEBI:16135
    • Isobutyric-d6 Acid
    • AI3-24260
    • 8LL210O1U0
    • 2-methyl-propanoic acid
    • NSC-62780
    • ISOPROPYLFORMIC-ACID
    • .alpha.-Methylpropionic acid
    • DTXCID601636
    • EC 201-195-7
    • 4-02-00-00843 (Beilstein Handbook Reference)
    • i-butyrate
    • iso-Butyrate
    • 2-Methylpropionate
    • Isobutyric acid [UN2529] [Flammable liquid]
    • ALQ
    • 2-methpropanoic acid
    • UN2529
    • Dimethylacetate
    • Isobuttersaure
    • Isopropylformate
    • Acido isobutirico
    • a-Methylpropanoate
    • a-Methylpropionate
    • Acide isobutyrique
    • 1iup
    • methylpropionic acid
    • alpha-Methylpropanoate
    • alpha-Methylpropionate
    • Tenox EBP 2
    • Tenox IBP 2
    • 2-Methyl-propionsaure
    • a-Methylpropanoic acid
    • a-Methylpropionic acid
    • Isobutyric acid, 99%
    • 2-methyl propanoic acid
    • 2-Propanecarboxylic acid
    • isopropyl carboxylic acid
    • FEMA Number: 2222
    • bmse000439
    • ISOBUTYRIC ACID [MI]
    • ISOBUTYRIC ACID [FCC]
    • WLN: QVY1&1
    • ISOBUTYRIC ACID [FHFI]
    • CHEMBL108778
    • GTPL1060
    • PROPANE-2-CARBOXYLIC ACID
    • BCP34521
    • EBA05408
    • NSC62780
    • STR03465
    • Isobutyric acid, analytical standard
    • Tox21_201207
    • LMFA01020071
    • STL146521
    • 2-METHYLPROPANOIC ACID [HSDB]
    • AKOS000118733
    • Isobutyric acid, >=99%, FCC, FG
    • DB02531
    • FI46255
    • UN 2529
    • CAS-79-31-2
    • NCGC00248957-01
    • NCGC00258759-01
    • I0103
    • Isobutyric acid, puriss. p.a., >=99.5%
    • NS00008728
    • EN300-19272
    • Isobutyric acid, natural, >=99%, FCC, FG
    • C02632
    • Q415062
    • F2191-0099
    • Z104473380
    • Isobutyric acid, certified reference material, TraceCERT(R)
    • 2-Methyl-d3-propionic-3,3,3-d3 acid;[2H6]-2-Methylpropionic acid
    • InChI=1/C4H8O2/c1-3(2)4(5)6/h3H,1-2H3,(H,5,6
    • 201-195-7

  • Applications

    Isobutyric acid (CAS 79-31-2) is a short-chain carboxylic acid with a pungent odor used widely in the flavor and fragrance sector to make fruity isobutyrate esters, as a palatability enhancer in animal feed, as an intermediate for pharmaceuticals targeting metabolic disorders, as a modifier and polymer starter in plastics and coatings, for synthesizing agrochemical isobutyrate derivatives, and also as a specialty solvent, analytical standard, and olfactory bait in insect traps, its favorable volatility and solvating power making it a versatile building block across modern chemical value chains.

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 157.8
    methanol 210.92
    isopropanol 99.37
    water 139.57
    ethyl acetate 24.04
    n-propanol 100.42
    acetone 45.1
    n-butanol 85.48
    acetonitrile 39.82
    DMF 82.63
    toluene 4.62
    isobutanol 82.99
    1,4-dioxane 53.11
    methyl acetate 36.25
    THF 74.85
    2-butanone 37.71
    n-pentanol 64.51
    sec-butanol 94.17
    n-hexane 6.64
    ethylene glycol 90.6
    NMP 128.0
    cyclohexane 2.88
    DMSO 92.47
    n-butyl acetate 19.42
    n-octanol 42.33
    chloroform 41.33
    n-propyl acetate 19.34
    acetic acid 204.33
    dichloromethane 33.36
    cyclohexanone 43.46
    propylene glycol 103.97
    isopropyl acetate 18.96
    DMAc 102.82
    2-ethoxyethanol 96.73
    isopentanol 81.69
    n-heptane 3.66
    ethyl formate 35.96
    1,2-dichloroethane 20.38
    n-hexanol 54.35
    2-methoxyethanol 142.74
    isobutyl acetate 14.17
    tetrachloromethane 17.13
    n-pentyl acetate 29.14
    transcutol 151.92
    n-heptanol 53.53
    ethylbenzene 6.4
    MIBK 25.41
    2-propoxyethanol 75.92
    tert-butanol 126.71
    MTBE 41.89
    2-butoxyethanol 85.68
    propionic acid 111.87
    o-xylene 8.12
    formic acid 214.51
    diethyl ether 19.13
    m-xylene 6.48
    p-xylene 10.75
    chlorobenzene 9.24
    dimethyl carbonate 12.27
    n-octane 2.77
    formamide 195.28
    cyclopentanone 68.09
    2-pentanone 28.29
    anisole 16.86
    cyclopentyl methyl ether 27.59
    gamma-butyrolactone 88.82
    1-methoxy-2-propanol 96.95
    pyridine 27.06
    3-pentanone 18.18
    furfural 78.76
    n-dodecane 2.21
    diethylene glycol 81.98
    diisopropyl ether 9.93
    tert-amyl alcohol 128.11
    acetylacetone 30.88
    n-hexadecane 2.25
    acetophenone 23.29
    methyl propionate 23.99
    isopentyl acetate 24.81
    trichloroethylene 39.01
    n-nonanol 35.08
    cyclohexanol 46.82
    benzyl alcohol 30.8
    2-ethylhexanol 32.32
    isooctanol 45.58
    dipropyl ether 11.76
    1,2-dichlorobenzene 12.36
    ethyl lactate 22.35
    propylene carbonate 52.72
    n-methylformamide 86.59
    2-pentanol 56.55
    n-pentane 5.0
    1-propoxy-2-propanol 50.29
    1-methoxy-2-propyl acetate 24.23
    2-(2-methoxypropoxy) propanol 62.5
    mesitylene 5.9
    ε-caprolactone 51.49
    p-cymene 8.04
    epichlorohydrin 58.84
    1,1,1-trichloroethane 21.72
    2-aminoethanol 148.17
    morpholine-4-carbaldehyde 100.57
    sulfolane 114.55
    2,2,4-trimethylpentane 6.94
    2-methyltetrahydrofuran 60.81
    n-hexyl acetate 39.48
    isooctane 4.33
    2-(2-butoxyethoxy)ethanol 86.6
    sec-butyl acetate 14.74
    tert-butyl acetate 27.41
    decalin 3.89
    glycerin 130.85
    diglyme 105.92
    acrylic acid 104.95
    isopropyl myristate 14.19
    n-butyric acid 92.9
    acetyl acetate 19.25
    di(2-ethylhexyl) phthalate 24.77
    ethyl propionate 15.14
    nitromethane 128.54
    1,2-diethoxyethane 27.22
    benzonitrile 20.08
    trioctyl phosphate 19.32
    1-bromopropane 12.51
    gamma-valerolactone 86.84
    n-decanol 24.4
    triethyl phosphate 13.04
    4-methyl-2-pentanol 41.69
    propionitrile 26.02
    vinylene carbonate 41.57
    1,1,2-trichlorotrifluoroethane 87.13
    DMS 21.31
    cumene 8.81
    2-octanol 36.91
    2-hexanone 25.46
    octyl acetate 21.6
    limonene 11.17
    1,2-dimethoxyethane 70.65
    ethyl orthosilicate 13.53
    tributyl phosphate 19.04
    diacetone alcohol 65.41
    N,N-dimethylaniline 20.96
    acrylonitrile 34.78
    aniline 19.97
    1,3-propanediol 136.69
    bromobenzene 6.39
    dibromomethane 22.43
    1,1,2,2-tetrachloroethane 39.83
    2-methyl-cyclohexyl acetate 23.04
    tetrabutyl urea 24.05
    diisobutyl methanol 19.64
    2-phenylethanol 29.53
    styrene 5.97
    dioctyl adipate 22.43
    dimethyl sulfate 26.66
    ethyl butyrate 15.41
    methyl lactate 35.5
    butyl lactate 37.98
    diethyl carbonate 11.16
    propanediol butyl ether 97.41
    triethyl orthoformate 13.88
    p-tert-butyltoluene 8.38
    methyl 4-tert-butylbenzoate 44.26
    morpholine 75.07
    tert-butylamine 69.7
    n-dodecanol 17.37
    dimethoxymethane 34.44
    ethylene carbonate 31.0
    cyrene 61.13
    2-ethoxyethyl acetate 33.6
    2-ethylhexyl acetate 18.01
    1,2,4-trichlorobenzene 16.12
    4-methylpyridine 26.01
    dibutyl ether 17.22
    2,6-dimethyl-4-heptanol 19.64
    DEF 38.94
    dimethyl isosorbide 69.67
    tetrachloroethylene 36.21
    eugenol 48.86
    triacetin 35.17
    span 80 66.11
    1,4-butanediol 77.03
    1,1-dichloroethane 20.92
    2-methyl-1-pentanol 71.35
    methyl formate 52.47
    2-methyl-1-butanol 82.73
    n-decane 3.48
    butyronitrile 31.45
    3,7-dimethyl-1-octanol 36.39
    1-chlorooctane 11.11
    1-chlorotetradecane 4.78
    n-nonane 3.39
    undecane 2.67
    tert-butylcyclohexane 5.72
    cyclooctane 1.84
    cyclopentanol 71.97
    tetrahydropyran 31.52
    tert-amyl methyl ether 37.08
    2,5,8-trioxanonane 78.27
    1-hexene 14.65
    2-isopropoxyethanol 69.99
    2,2,2-trifluoroethanol 98.44
    methyl butyrate 25.59

    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

Botanical

Name CAS Botanical Proportion
Blackcurrant bud 1 68606-81-5 Ribes nigrum L., fam. Grossulariaceae 0.04%
Hedychium coronarium flower (Japan) Hedychium coronarium Koenig, fam. Zingiberaceae 0.03%
Zizyphus jujuba fruit (Malaysia) Zizyphus jujuba Mill. var. inermis, fam. Rhamnaceae 0.01%
Roman chamomile (Germany) 1a hydrodistillate 8015-92-7 Anthemis nobilis L., fam. Asteraceae (Compositae) 0.03%
Spearmint, scotch (Japan) Mentha gracilis Sole, fam. Lamiaceae (Labiatae) 0.74%
Olibanum, African (Oman) 8016-36-2 Boswellia frereana Birdwood, fam. Burseraceae 0.1%
Mango (India) 1a cv. Langra 90063-86-8 Mangifera indica L. cv. Langra, fam. Anacardiaceae 4.3%
Chicory root, roasted 2 68650-43-1 Cichorium intybus L., fam. Asteraceae (Compositae) 0.33%
Carob bean powder 2a raw 9000-40-2 Ceratonia siliqua L., fam. Leguminoseae 27.1%
Carob bean powder 2b roasted 9000-40-2 Ceratonia siliqua L., fam. Leguminoseae 30.0%
Rocket leaf 1 Eruca sativa L., fam. Brassicaceae 0.1%