2-Hydroxy-5-methylpyrazine

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  • Identifiers

    CAS number
    20721-17-9

    Molecular formula
    C5H6N2O

    SMILES
    CC1=CNC(=O)C=N1

    Safety labels

  • Odor profile

    Fragrance
    Nutty 64.5%
    Roasted 56.75%
    Burnt 45.07%
    Popcorn 41.22%
    Coffee 37.34%
    Hazelnut 34.74%
    Musty 34.56%
    Cocoa 34.26%
    Odorless 34.06%
    Caramellic 29.22%

     

    Flavor
    Nutty 46.98%
    Bitter 43.33%
    Cocoa 35.88%
    Almond 34.83%
    Popcorn 31.78%
    Coffee 30.69%
    Musty 30.21%
    Bread 28.89%
    Chocolate 28.03%
    Sulfur 25.14%

     

    Odor impact est.
    High

  • Properties

    XLogP3-AA
    -0.3

    pKa est.
    7.36 (neutral)

    Molecular weight
    110.11 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra slow

    Boiling point est.
    331°C

    Flash point

    • 136.56 ˚C est.

  • Synonyms

    • 2-Hydroxy-5-methylpyrazine
    • 20721-17-9
    • 2(1H)-Pyrazinone, 5-methyl-
    • Pyrazinol, 5-methyl-
    • 5-Methyl-2(1H)-pyrazone
    • 5-methylpyrazinol
    • Pyrazine, 2-hydroxy-5-methyl-
    • UNII-EX039G48ZE
    • NSC 143658
    • EX039G48ZE
    • NSC-143658
    • 5-METHYL-2-PYRAZINOL
    • DTXSID70174787
    • 3,4-DIHYDRO-6-METHYL-3-OXOPYRAZINE
    • RefChem:87443
    • Pyrazinol, 5-methyl-(8CI)
    • DTXCID7097278
    • 2(1H)-Pyrazinone, 5-methyl-(9CI)
    • 5-Methylpyrazin-2(1H)-one
    • 5-methylpyrazin-2-ol
    • 5-methyl-1H-pyrazin-2-one
    • 5-Methyl-2(1H)-pyrazinone
    • MFCD19216543
    • MFCD01693937
    • 5-methyl-pyrazinone
    • 5-methyl-1,2-dihydropyrazin-2-one
    • NSC143658
    • SCHEMBL752334
    • orb3023285
    • SCHEMBL1563585
    • SCHEMBL9901454
    • SCHEMBL9902187
    • SCHEMBL16540997
    • SCHEMBL27852656
    • AKOS006349280
    • AKOS015856433
    • CS-W008795
    • GS-5795
    • SY027652
    • DB-002456
    • EN300-86098
    • 721H179
    • F077046
    • Q27277402
    • 20721-17-9

  • Applications

    2-Hydroxy-5-methylpyrazine, CAS 20721-17-9, is used primarily as a fragrance and flavor ingredient in the perfumery and food industries, where its pyrazine roasty/nutty character can help define notes in fragrance formulations and flavor profiles; it is also used as an intermediate for synthesizing pyrazine derivatives in industrial chemistry and pharmaceutical manufacturing; in cosmetics and personal care, it may appear as part of fragrance compositions; in household cleaning and consumer products, it can function as an odorant to improve scent perception; its use is subject to local regulations and formulation limits.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 6.97
    methanol 13.88
    isopropanol 3.56
    water 6.86
    ethyl acetate 1.19
    n-propanol 4.13
    acetone 1.39
    n-butanol 2.96
    acetonitrile 0.96
    DMF 39.86
    toluene 0.48
    isobutanol 2.96
    1,4-dioxane 2.64
    methyl acetate 2.14
    THF 5.84
    2-butanone 1.57
    n-pentanol 2.18
    sec-butanol 2.52
    n-hexane 0.05
    ethylene glycol 6.87
    NMP 27.51
    cyclohexane 0.04
    DMSO 33.01
    n-butyl acetate 2.28
    n-octanol 0.97
    chloroform 2.18
    n-propyl acetate 0.86
    acetic acid 3.78
    dichloromethane 2.64
    cyclohexanone 3.43
    propylene glycol 5.61
    isopropyl acetate 0.87
    DMAc 44.74
    2-ethoxyethanol 8.17
    isopentanol 3.07
    n-heptane 0.1
    ethyl formate 6.05
    1,2-dichloroethane 1.53
    n-hexanol 2.37
    2-methoxyethanol 22.31
    isobutyl acetate 0.74
    tetrachloromethane 0.7
    n-pentyl acetate 1.48
    transcutol 13.99
    n-heptanol 1.53
    ethylbenzene 0.46
    MIBK 1.17
    2-propoxyethanol 9.29
    tert-butanol 3.88
    MTBE 0.98
    2-butoxyethanol 6.63
    propionic acid 4.02
    o-xylene 0.86
    formic acid 16.7
    diethyl ether 0.41
    m-xylene 0.71
    p-xylene 0.79
    chlorobenzene 0.91
    dimethyl carbonate 2.45
    n-octane 0.05
    formamide 15.35
    cyclopentanone 4.97
    2-pentanone 1.05
    anisole 1.69
    cyclopentyl methyl ether 1.44
    gamma-butyrolactone 9.23
    1-methoxy-2-propanol 11.01
    pyridine 3.32
    3-pentanone 0.7
    furfural 18.9
    n-dodecane 0.05
    diethylene glycol 13.75
    diisopropyl ether 0.2
    tert-amyl alcohol 3.3
    acetylacetone 1.92
    n-hexadecane 0.06
    acetophenone 2.68
    methyl propionate 2.08
    isopentyl acetate 2.7
    trichloroethylene 2.74
    n-nonanol 1.01
    cyclohexanol 1.56
    benzyl alcohol 3.36
    2-ethylhexanol 1.57
    isooctanol 1.36
    dipropyl ether 0.77
    1,2-dichlorobenzene 1.57
    ethyl lactate 2.32
    propylene carbonate 5.83
    n-methylformamide 19.25
    2-pentanol 1.1
    n-pentane 0.05
    1-propoxy-2-propanol 5.94
    1-methoxy-2-propyl acetate 3.71
    2-(2-methoxypropoxy) propanol 8.17
    mesitylene 0.5
    ε-caprolactone 5.01
    p-cymene 0.93
    epichlorohydrin 8.13
    1,1,1-trichloroethane 0.95
    2-aminoethanol 10.55
    morpholine-4-carbaldehyde 22.57
    sulfolane 16.53
    2,2,4-trimethylpentane 0.07
    2-methyltetrahydrofuran 2.76
    n-hexyl acetate 1.58
    isooctane 0.05
    2-(2-butoxyethoxy)ethanol 8.83
    sec-butyl acetate 0.63
    tert-butyl acetate 1.22
    decalin 0.08
    glycerin 13.9
    diglyme 15.14
    acrylic acid 4.58
    isopropyl myristate 0.76
    n-butyric acid 4.42
    acetyl acetate 0.98
    di(2-ethylhexyl) phthalate 2.44
    ethyl propionate 0.97
    nitromethane 6.98
    1,2-diethoxyethane 1.84
    benzonitrile 3.02
    trioctyl phosphate 1.39
    1-bromopropane 0.71
    gamma-valerolactone 13.92
    n-decanol 0.83
    triethyl phosphate 2.17
    4-methyl-2-pentanol 1.07
    propionitrile 1.65
    vinylene carbonate 6.57
    1,1,2-trichlorotrifluoroethane 11.99
    DMS 2.23
    cumene 0.59
    2-octanol 0.75
    2-hexanone 0.95
    octyl acetate 1.11
    limonene 0.86
    1,2-dimethoxyethane 10.57
    ethyl orthosilicate 1.91
    tributyl phosphate 1.67
    diacetone alcohol 4.01
    N,N-dimethylaniline 2.44
    acrylonitrile 3.16
    aniline 2.05
    1,3-propanediol 10.86
    bromobenzene 0.7
    dibromomethane 1.34
    1,1,2,2-tetrachloroethane 2.83
    2-methyl-cyclohexyl acetate 2.13
    tetrabutyl urea 2.95
    diisobutyl methanol 1.18
    2-phenylethanol 3.55
    styrene 0.45
    dioctyl adipate 1.68
    dimethyl sulfate 7.14
    ethyl butyrate 1.67
    methyl lactate 5.33
    butyl lactate 3.32
    diethyl carbonate 1.8
    propanediol butyl ether 6.25
    triethyl orthoformate 2.03
    p-tert-butyltoluene 0.83
    methyl 4-tert-butylbenzoate 4.45
    morpholine 5.01
    tert-butylamine 1.61
    n-dodecanol 0.65
    dimethoxymethane 7.5
    ethylene carbonate 4.49
    cyrene 7.98
    2-ethoxyethyl acetate 2.68
    2-ethylhexyl acetate 2.03
    1,2,4-trichlorobenzene 2.2
    4-methylpyridine 4.48
    dibutyl ether 0.62
    2,6-dimethyl-4-heptanol 1.18
    DEF 4.93
    dimethyl isosorbide 11.58
    tetrachloroethylene 2.27
    eugenol 5.82
    triacetin 2.31
    span 80 4.57
    1,4-butanediol 4.6
    1,1-dichloroethane 0.94
    2-methyl-1-pentanol 2.39
    methyl formate 12.4
    2-methyl-1-butanol 2.82
    n-decane 0.07
    butyronitrile 1.92
    3,7-dimethyl-1-octanol 1.4
    1-chlorooctane 0.28
    1-chlorotetradecane 0.17
    n-nonane 0.05
    undecane 0.06
    tert-butylcyclohexane 0.1
    cyclooctane 0.03
    cyclopentanol 2.75
    tetrahydropyran 1.1
    tert-amyl methyl ether 1.0
    2,5,8-trioxanonane 12.37
    1-hexene 0.22
    2-isopropoxyethanol 4.04
    2,2,2-trifluoroethanol 4.08
    methyl butyrate 1.89

    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