Methylthiouracil

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  • Identifiers

    CAS number
    56-04-2

    Molecular formula
    C5H6N2OS

    SMILES
    CC1=CC(=O)NC(=S)N1

    Safety labels

    Irritant
    Irritant

    Health Hazard
    Health

  • Odor profile

    Fragrance
    Odorless 52.31%
    Burnt 34.91%
    Roasted 25.86%
    Sulfurous 25.82%
    Pungent 25.74%
    Nutty 24.09%
    Cooked 23.39%
    Meaty 22.07%
    Bitter 21.41%
    Savory 18.8%

     

    Flavor
    Bitter 54.73%
    Odorless 31.93%
    Nutty 26.94%
    Bread crust 21.2%
    Formyl 21.09%
    Nitrile 20.86%
    Mild 20.72%
    Rotten 20.32%
    Roasted peanuts 20.31%
    Furfural 20.21%

     

    Odor impact est.
    Low

  • Properties

    XLogP3-AA
    -0.2

    pKa est.
    8.44 (weak base)

    Molecular weight
    142.18 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra slow

    Boiling point est.
    430°C

    Melting point expt.

    • 570 to 577 °F (Decomposes) (NTP, 1992)

    Flash point

    • 161.39 ˚C est.

    Solubility expt.

    • less than 1 mg/mL at 73 °F (NTP, 1992)
    • VERY SLIGHTLY SOL IN COLD WATER, ETHER; ONE PART DISSOLVES IN ABOUT 150 PARTS BOILING WATER; SLIGHTLY SOL IN ALCOHOL, ACETONE; PRACTICALLY INSOL IN BENZENE, CHLOROFORM. FREELY SOL IN AQ SOLN OF AMMONIA & ALKALI HYDROXIDES.
    • Water solubility of 533.2 mg/l at 25 °C.

  • Synonyms

    • methylthiouracil
    • 6-Methyl-2-thiouracil
    • 56-04-2
    • 4-hydroxy-2-mercapto-6-methylpyrimidine
    • Thimecil
    • 2-Mercapto-6-methylpyrimidin-4-ol
    • Methiocil
    • Alkiron
    • Metacil
    • 2-Thio-6-methyluracil
    • Methacil
    • Thiomecil
    • Thiothymin
    • Thyreostat
    • Basethyrin
    • Prostrumyl
    • Thyreonorm
    • Tiomeracil
    • Antibason
    • Basecil
    • Methiacil
    • Methicil
    • Muracil
    • Orcanon
    • Strumacil
    • Thiomidil
    • Thioryl
    • Thiuryl
    • Tiotiron
    • Thyril
    • Thyreostat I
    • Tiorale M
    • 6-Methylthiouracil
    • 4(1H)-Pyrimidinone, 2,3-dihydro-6-methyl-2-thioxo-
    • 4-Methyl-2-thiouracil
    • Methyl thiouracil
    • 6-methyl-2-thioxo-2,3-dihydropyrimidin-4(1H)-one
    • 6-Thio-4-methyluracil
    • Usaf ek-6454
    • Methacil (VAN)
    • Metacil (VAN)
    • Metiltiouracilo
    • 6-Methyl-2-mercaptouracil
    • Thiothyron
    • Uracil, 6-methyl-2-thio-
    • Methylthiouracile
    • 6-methyl-2-sulfanylpyrimidin-4-ol
    • 6-Methyl-2-thiouracyl
    • Methylthiouracil [INN]
    • Rcra waste number U164
    • 6-Metil-tiouracile
    • 2-Mercapto-4-hydroxy-6-methylpyrimidine
    • 2-Mercapto-6-methylpyrimid-4-one
    • 2-Mercapto-6-methylpyrimidin-4(1H)-one
    • CCRIS 409
    • Metiltiouracilo [INN-Spanish]
    • Muracin
    • Methylthiouracile [INN-French]
    • Methylthiouracilum [INN-Latin]
    • Metiur
    • 91795-77-6
    • 2-Thio-6-methyl-1,3-pyrimidin-4-one
    • HSDB 3366
    • 2-Thio-4-oxo-6-methyl-1,3-pyrimidine
    • 2-Mercapto-6-methyl-4-pyrimidone
    • 2-Mercapto-6-methyl-4-pyrimidinol
    • EINECS 200-252-3
    • 4-Hydroxy-6-methyl-2-thiopyrimidine
    • 6-methyl-2-sulfanylidene-1H-pyrimidin-4-one
    • Methylthiouracil [USP:INN]
    • Thimecil (TN)
    • NSC 193526
    • NSC-193526
    • UNII-QW24888U5F
    • DTXSID2020890
    • 2,3-Dihydro-6-methyl-2-thioxo-4(1H)-pyrimidinone
    • AI3-25476
    • Methylthiouracil (INN)
    • QW24888U5F
    • 6-Methyl-2-thio-2,4-(1H,3H)-pyrimidinedione
    • MTU
    • 2-Thiouracil, 6-methyl-
    • METHYLTHIOURACIL [MI]
    • 6-Methyl-4-oxo-2-thioxo1,2,3,4-tetrahydropyrimidine
    • DTXCID60890
    • METHYLTHIOURACIL [HSDB]
    • METHYLTHIOURACIL [IARC]
    • MLS000069452
    • 6-methyl-2-sulfanylidene-1,2,3,4-tetrahydropyrimidin-4-one
    • METHYLTHIOURACIL [MART.]
    • CHEBI:82346
    • URACIL,6-METHYL,2-THIO
    • METHYLTHIOURACIL [WHO-DD]
    • NSC 9378
    • NSC 43815
    • 1123-10-0
    • NCGC00091124-02
    • SMR000059030
    • 6-Methyl-2-thio-2,4(1H,3H)-pyrimidinedione
    • 6-?Methyl-?2-?thiouracil
    • Methylthiouracil (USP:INN)
    • Alkiron (VAN)
    • Metiltiouracilo (INN-Spanish)
    • WLN: T6MYMVJ BUS F1
    • METHYLTHIOURACIL (IARC)
    • Methylthiouracile (INN-French)
    • Methylthiouracilum (INN-Latin)
    • 6-Methyl-4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine
    • METHYLTHIOURACIL (MART.)
    • Metiltiouracile
    • Metiltiouracile [DCIT]
    • Methylthiouracilum
    • CAS-56-04-2
    • 6-Methyl-2-thio-2,3H)-pyrimidinedione
    • 6-Methyl-2-(methylthio)-4(3H)-pyrimidinone; 6-Methyl-2-(methylthio)-4-hydroxypyrimidine; 6-Methyl-2-(methylthio)-4-pyrimidone; NSC 193525; NSC 37678
    • 6-Metil-tiouracile [Italian]
    • 6-Methyl-2-thiouracyl [Czech]
    • RCRA waste no. U164
    • methyl-thiouracil
    • 6-Methyl-2-thio-2,4-(1H3H)-pyrimidinedione
    • Prestwick_330
    • Methyl-6-thiouracil
    • MFCD00006040
    • Spectrum_001031
    • Opera_ID_172
    • Spectrum2_001276
    • Spectrum3_000676
    • Spectrum4_000864

  • Applications

    Methylthiouracil (CAS 56-04-2) is primarily used as a chemical intermediate in the synthesis of thiouracil-based pharmaceutical agents and related heterocyclic compounds. In practice, it serves as a building block in medicinal chemistry research and early-stage production, where it is converted into more advanced thiouracil derivatives. It may also be evaluated as a precursor in agrochemical or specialty chemical development and in academic research settings for exploration of nucleobase analogs and related structures. Its use is subject to local regulations and formulation limits.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 9.76
    methanol 11.28
    isopropanol 5.36
    water 2.05
    ethyl acetate 9.89
    n-propanol 6.53
    acetone 29.06
    n-butanol 5.13
    acetonitrile 12.39
    DMF 71.02
    toluene 0.62
    isobutanol 4.47
    1,4-dioxane 12.42
    methyl acetate 13.08
    THF 36.95
    2-butanone 14.82
    n-pentanol 4.82
    sec-butanol 4.1
    n-hexane 0.09
    ethylene glycol 11.72
    NMP 54.5
    cyclohexane 0.03
    DMSO 109.61
    n-butyl acetate 7.5
    n-octanol 3.49
    chloroform 1.5
    n-propyl acetate 8.89
    acetic acid 31.11
    dichloromethane 2.23
    cyclohexanone 10.97
    propylene glycol 12.44
    isopropyl acetate 6.31
    DMAc 59.28
    2-ethoxyethanol 24.67
    isopentanol 4.87
    n-heptane 0.17
    ethyl formate 10.84
    1,2-dichloroethane 2.04
    n-hexanol 4.28
    2-methoxyethanol 43.61
    isobutyl acetate 6.27
    tetrachloromethane 0.25
    n-pentyl acetate 6.05
    transcutol 54.82
    n-heptanol 2.96
    ethylbenzene 0.38
    MIBK 8.08
    2-propoxyethanol 27.14
    tert-butanol 6.95
    MTBE 3.17
    2-butoxyethanol 13.57
    propionic acid 12.55
    o-xylene 0.64
    formic acid 22.86
    diethyl ether 2.92
    m-xylene 0.94
    p-xylene 0.61
    chlorobenzene 1.08
    dimethyl carbonate 12.61
    n-octane 0.07
    formamide 24.93
    cyclopentanone 25.03
    2-pentanone 11.68
    anisole 4.26
    cyclopentyl methyl ether 6.3
    gamma-butyrolactone 34.81
    1-methoxy-2-propanol 32.05
    pyridine 5.36
    3-pentanone 7.09
    furfural 35.69
    n-dodecane 0.11
    diethylene glycol 35.73
    diisopropyl ether 0.95
    tert-amyl alcohol 5.15
    acetylacetone 23.17
    n-hexadecane 0.12
    acetophenone 7.26
    methyl propionate 12.42
    isopentyl acetate 7.19
    trichloroethylene 4.34
    n-nonanol 3.41
    cyclohexanol 2.36
    benzyl alcohol 5.75
    2-ethylhexanol 3.17
    isooctanol 2.88
    dipropyl ether 3.69
    1,2-dichlorobenzene 1.42
    ethyl lactate 12.13
    propylene carbonate 19.23
    n-methylformamide 25.69
    2-pentanol 2.83
    n-pentane 0.08
    1-propoxy-2-propanol 18.25
    1-methoxy-2-propyl acetate 16.26
    2-(2-methoxypropoxy) propanol 22.0
    mesitylene 0.66
    ε-caprolactone 13.38
    p-cymene 1.05
    epichlorohydrin 25.94
    1,1,1-trichloroethane 1.68
    2-aminoethanol 13.31
    morpholine-4-carbaldehyde 52.77
    sulfolane 53.69
    2,2,4-trimethylpentane 0.1
    2-methyltetrahydrofuran 11.13
    n-hexyl acetate 7.99
    isooctane 0.1
    2-(2-butoxyethoxy)ethanol 24.76
    sec-butyl acetate 5.17
    tert-butyl acetate 8.13
    decalin 0.09
    glycerin 27.99
    diglyme 35.84
    acrylic acid 16.35
    isopropyl myristate 3.74
    n-butyric acid 11.73
    acetyl acetate 8.88
    di(2-ethylhexyl) phthalate 7.29
    ethyl propionate 8.18
    nitromethane 67.47
    1,2-diethoxyethane 9.14
    benzonitrile 5.2
    trioctyl phosphate 4.94
    1-bromopropane 0.88
    gamma-valerolactone 46.64
    n-decanol 2.7
    triethyl phosphate 5.99
    4-methyl-2-pentanol 2.58
    propionitrile 5.56
    vinylene carbonate 15.58
    1,1,2-trichlorotrifluoroethane 25.36
    DMS 10.32
    cumene 0.55
    2-octanol 2.09
    2-hexanone 9.08
    octyl acetate 5.34
    limonene 1.36
    1,2-dimethoxyethane 30.23
    ethyl orthosilicate 5.02
    tributyl phosphate 6.04
    diacetone alcohol 18.61
    N,N-dimethylaniline 3.7
    acrylonitrile 9.16
    aniline 2.77
    1,3-propanediol 15.35
    bromobenzene 0.67
    dibromomethane 1.12
    1,1,2,2-tetrachloroethane 3.1
    2-methyl-cyclohexyl acetate 7.18
    tetrabutyl urea 8.9
    diisobutyl methanol 2.17
    2-phenylethanol 6.02
    styrene 0.43
    dioctyl adipate 8.04
    dimethyl sulfate 29.19
    ethyl butyrate 7.18
    methyl lactate 20.08
    butyl lactate 9.86
    diethyl carbonate 6.12
    propanediol butyl ether 17.9
    triethyl orthoformate 6.34
    p-tert-butyltoluene 1.07
    methyl 4-tert-butylbenzoate 12.55
    morpholine 16.64
    tert-butylamine 2.19
    n-dodecanol 2.07
    dimethoxymethane 33.33
    ethylene carbonate 11.11
    cyrene 28.18
    2-ethoxyethyl acetate 12.55
    2-ethylhexyl acetate 5.29
    1,2,4-trichlorobenzene 2.36
    4-methylpyridine 5.71
    dibutyl ether 2.52
    2,6-dimethyl-4-heptanol 2.17
    DEF 14.04
    dimethyl isosorbide 34.57
    tetrachloroethylene 1.56
    eugenol 15.3
    triacetin 14.04
    span 80 14.34
    1,4-butanediol 8.34
    1,1-dichloroethane 1.59
    2-methyl-1-pentanol 4.52
    methyl formate 25.71
    2-methyl-1-butanol 4.29
    n-decane 0.15
    butyronitrile 5.71
    3,7-dimethyl-1-octanol 3.65
    1-chlorooctane 0.89
    1-chlorotetradecane 0.49
    n-nonane 0.12
    undecane 0.13
    tert-butylcyclohexane 0.14
    cyclooctane 0.02
    cyclopentanol 5.59
    tetrahydropyran 3.88
    tert-amyl methyl ether 3.28
    2,5,8-trioxanonane 31.9
    1-hexene 0.49
    2-isopropoxyethanol 16.57
    2,2,2-trifluoroethanol 16.58
    methyl butyrate 10.17

    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