Letrozole

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  • Identifiers

    CAS number
    112809-51-5

    Molecular formula
    C17H11N5

    SMILES
    C1=CC(=CC=C1C#N)C(C2=CC=C(C=C2)C#N)N3C=NC=N3

    Safety labels

    Irritant
    Irritant

    Health Hazard
    Health

  • Odor profile

    Fragrance
    Floral 50.79%
    Sweet 36.96%
    Bitter 33.84%
    Spicy 29.31%
    Almond 27.15%
    Animal 25.95%
    Powdery 23.19%
    Honey 21.72%
    Neroli 21.4%
    Aromatic 21.26%

     

    Flavor
    Bitter 86.93%
    Odorless 26.97%
    Nitrile 20.19%
    Very strong 18.77%
    Indole 18.39%
    Moth ball 17.52%
    Cedarleaf 17.38%
    Sweet-like 17.34%
    Rotten 17.01%
    Naphthelene 16.95%

     

    Odor impact est.
    Low

  • Properties

    XLogP3-AA
    2.7

    pKa est.
    5.25 (weak acid)

    Molecular weight
    285.3 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra slow

    Boiling point est.
    1151°C

    Melting point expt.

    • 184-185 °C
    • 181-183 °C
    • 184 - 185 °C

    Flash point

    • 255.4 ˚C est.

    Solubility expt.

    • Freely soluble in dichloromethane; slightly soluble in ethanol; practically insoluble in water
    • 7.99e-02 g/L

  • Synonyms

    • letrozole
    • 112809-51-5
    • Femara
    • 4,4'-((1h-1,2,4-triazol-1-yl)methylene)dibenzonitrile
    • Letrozol
    • CGS 20267
    • Letoval
    • CGS-20267
    • Benzonitrile, 4,4'-(1H-1,2,4-triazol-1-ylmethylene)bis-
    • 4,4'-(1h-1,2,4-triazol-1-ylmethylene)bisbenzonitrile
    • 4,4'-(1H-1,2,4-Triazol-1-ylmethylene)dibenzonitrile
    • 4-[(4-cyanophenyl)-(1,2,4-triazol-1-yl)methyl]benzonitrile
    • Femera
    • 4,4'-(1H-1,2,4-triazol-1-ylmethanediyl)dibenzonitrile
    • HSDB 7461
    • UNII-7LKK855W8I
    • NSC-759652
    • 7LKK855W8I
    • CCRIS 8822
    • CHEBI:6413
    • DTXSID4023202
    • CGS20267
    • CHEMBL1444
    • 4-[(4-CYANOPHENYL)(1H-1,2,4-TRIAZOL-1-YL)METHYL]BENZONITRILE
    • DTXCID503202
    • Letrozole [USAN:USP:INN:BAN]
    • NSC719345
    • NSC 759652
    • 4,4'-(1h-1,2,4-triazol-1-ylmethylene) bis-benzonitrile
    • NCGC00016973-01
    • CAS-112809-51-5
    • LETROZOLE (MART.)
    • LETROZOLE [MART.]
    • LETROZOLE (USP-RS)
    • LETROZOLE [USP-RS]
    • KISQALI FEMARA CO-PACK COMPONENT LETROZOLE
    • C17H11N5
    • LETROZOLE (EP IMPURITY)
    • LETROZOLE [EP IMPURITY]
    • LETROZOLE (EP MONOGRAPH)
    • LETROZOLE [EP MONOGRAPH]
    • LETROZOLE (USP MONOGRAPH)
    • LETROZOLE [USP MONOGRAPH]
    • Letrozole (USAN:USP:INN:BAN)
    • SMR000466343
    • Femara (TN)
    • LETRAZOLE
    • SR-01000759382
    • letrozolum
    • Letrozole (JAN/USP/INN)
    • 4,4'-(1h-1,2,4-triazol-1-ylmethylene)bis-benzonitrile
    • Letrozole?
    • Letrozole Tablets
    • 1-[bis(4-cyanophenyl)methyl]-1,2,4-triazole
    • FEM-345
    • Femara, Letrozole
    • Letrozole (Standard)
    • 4,4'-(1H-1,2,4-triazol-1-yl-methylene)-bis(benzonitrile)
    • LETROZOLE [INN]
    • LETROZOLE [JAN]
    • LETROZOLE [MI]
    • LETROZOLE [HSDB]
    • LETROZOLE [USAN]
    • Prestwick0_001025
    • Prestwick1_001025
    • Prestwick2_001025
    • Prestwick3_001025
    • Femara (TN) (Novartis)
    • LETROZOLE [WHO-DD]
    • SCHEMBL4331
    • 1-[Bis-(4-cyanophenyl)methyl]-1,2,4-triazole
    • BIDD:PXR0130
    • BSPBio_001209
    • MLS000759455
    • MLS001424038
    • MLS002584991
    • MLS006010040
    • BIDD:GT0015
    • Letrozole - Bio-X trade mark
    • SPBio_003070
    • BPBio1_001331
    • GTPL5209
    • LETROZOLE [ORANGE BOOK]
    • Letrozole, >=98% (HPLC)
    • BDBM13061
    • EX-A965
    • L02BG04
    • HMS1571M11
    • HMS2051E08
    • HMS2089L22
    • HMS2098M11
    • HMS2233C23
    • HMS3369E11
    • HMS3393E08
    • HMS3651K05
    • HMS3715M11
    • Pharmakon1600-01502354
    • BCP23354
    • IVB71296
    • Tox21_110719
    • Tox21_303572
    • HY-14248R
    • MFCD00866241
    • NSC759652
    • s1235
    • STL451047
    • AKOS005145822
    • AB07525
    • AC-1193
    • BCP9000848
    • CCG-100849
    • CS-1776
    • DB01006
    • FL24873
    • KS-1269
    • NC00099
    • NSC-719345
    • NCGC00016973-02
    • NCGC00016973-03
    • NCGC00016973-06
    • NCGC00257460-01
    • BL164620
    • HY-14248
    • BCP0726000213
    • 1-Bis(4-cyanophenyl)methyl-1,2,4-triazole
    • 4,2,4-Triazol-1-ylmethylene)dibenzonitrile
    • AB00514009
    • L0248

  • Applications

    Letrozole, CAS 112809-51-5, is primarily used as an active pharmaceutical ingredient (API) in pharmaceutical products with hormone-related indications, acting as an aromatase inhibitor. It may also be used as a research and development chemical for pharmaceutical synthesis at laboratory and production scales, and as an analytical reference standard for quality control and assay development in pharmaceutical laboratories. In industrial manufacturing contexts, the compound can serve as a building block for exploratory syntheses related to aromatase inhibitors and as part of API production routes, subject to local regulations and formulation constraints. Additional applications include use as a reference standard for purity and stability testing within GMP-controlled workflows and supporting pharmacological research and structure–activity studies.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 4.6
    methanol 12.31
    isopropanol 2.35
    water 0.24
    ethyl acetate 22.31
    n-propanol 2.95
    acetone 83.41
    n-butanol 2.35
    acetonitrile 60.12
    DMF 153.65
    toluene 10.87
    isobutanol 2.38
    1,4-dioxane 32.28
    methyl acetate 52.78
    THF 80.45
    2-butanone 49.44
    n-pentanol 4.77
    sec-butanol 2.17
    n-hexane 0.26
    ethylene glycol 13.41
    NMP 66.64
    cyclohexane 0.3
    DMSO 163.87
    n-butyl acetate 12.84
    n-octanol 4.6
    chloroform 70.17
    n-propyl acetate 19.3
    acetic acid 27.5
    dichloromethane 98.09
    cyclohexanone 43.83
    propylene glycol 7.63
    isopropyl acetate 13.29
    DMAc 160.99
    2-ethoxyethanol 24.59
    isopentanol 2.98
    n-heptane 0.74
    ethyl formate 29.0
    1,2-dichloroethane 57.49
    n-hexanol 5.83
    2-methoxyethanol 32.08
    isobutyl acetate 12.99
    tetrachloromethane 5.03
    n-pentyl acetate 12.39
    transcutol 48.79
    n-heptanol 5.52
    ethylbenzene 6.12
    MIBK 14.46
    2-propoxyethanol 23.24
    tert-butanol 3.97
    MTBE 3.69
    2-butoxyethanol 16.77
    propionic acid 16.44
    o-xylene 5.79
    formic acid 26.97
    diethyl ether 5.78
    m-xylene 5.77
    p-xylene 9.22
    chlorobenzene 24.51
    dimethyl carbonate 39.86
    n-octane 0.57
    formamide 57.57
    cyclopentanone 87.45
    2-pentanone 22.54
    anisole 18.34
    cyclopentyl methyl ether 12.77
    gamma-butyrolactone 91.36
    1-methoxy-2-propanol 19.28
    pyridine 56.52
    3-pentanone 25.32
    furfural 90.32
    n-dodecane 0.74
    diethylene glycol 31.0
    diisopropyl ether 1.95
    tert-amyl alcohol 3.1
    acetylacetone 52.6
    n-hexadecane 0.84
    acetophenone 27.72
    methyl propionate 30.59
    isopentyl acetate 12.38
    trichloroethylene 122.34
    n-nonanol 5.43
    cyclohexanol 3.56
    benzyl alcohol 18.42
    2-ethylhexanol 5.47
    isooctanol 4.99
    dipropyl ether 7.66
    1,2-dichlorobenzene 22.75
    ethyl lactate 18.36
    propylene carbonate 40.86
    n-methylformamide 58.16
    2-pentanol 1.77
    n-pentane 0.16
    1-propoxy-2-propanol 14.88
    1-methoxy-2-propyl acetate 22.35
    2-(2-methoxypropoxy) propanol 20.74
    mesitylene 3.54
    ε-caprolactone 30.16
    p-cymene 5.5
    epichlorohydrin 95.83
    1,1,1-trichloroethane 28.37
    2-aminoethanol 9.08
    morpholine-4-carbaldehyde 63.99
    sulfolane 93.26
    2,2,4-trimethylpentane 0.22
    2-methyltetrahydrofuran 18.52
    n-hexyl acetate 12.3
    isooctane 0.2
    2-(2-butoxyethoxy)ethanol 23.62
    sec-butyl acetate 11.54
    tert-butyl acetate 12.54
    decalin 0.53
    glycerin 20.85
    diglyme 49.55
    acrylic acid 28.4
    isopropyl myristate 7.29
    n-butyric acid 13.34
    acetyl acetate 23.56
    di(2-ethylhexyl) phthalate 10.63
    ethyl propionate 17.87
    nitromethane 132.1
    1,2-diethoxyethane 17.56
    benzonitrile 30.9
    trioctyl phosphate 7.1
    1-bromopropane 10.89
    gamma-valerolactone 85.42
    n-decanol 4.69
    triethyl phosphate 11.02
    4-methyl-2-pentanol 2.38
    propionitrile 25.8
    vinylene carbonate 48.99
    1,1,2-trichlorotrifluoroethane 72.17
    DMS 25.44
    cumene 4.64
    2-octanol 3.6
    2-hexanone 21.83
    octyl acetate 9.18
    limonene 5.6
    1,2-dimethoxyethane 43.8
    ethyl orthosilicate 9.27
    tributyl phosphate 8.51
    diacetone alcohol 18.41
    N,N-dimethylaniline 12.52
    acrylonitrile 56.49
    aniline 14.58
    1,3-propanediol 7.99
    bromobenzene 24.21
    dibromomethane 41.26
    1,1,2,2-tetrachloroethane 67.61
    2-methyl-cyclohexyl acetate 13.29
    tetrabutyl urea 13.07
    diisobutyl methanol 3.88
    2-phenylethanol 16.87
    styrene 8.59
    dioctyl adipate 13.55
    dimethyl sulfate 71.53
    ethyl butyrate 14.24
    methyl lactate 28.64
    butyl lactate 13.81
    diethyl carbonate 13.86
    propanediol butyl ether 12.97
    triethyl orthoformate 11.62
    p-tert-butyltoluene 4.5
    methyl 4-tert-butylbenzoate 20.98
    morpholine 27.72
    tert-butylamine 2.05
    n-dodecanol 4.04
    dimethoxymethane 60.72
    ethylene carbonate 36.09
    cyrene 31.71
    2-ethoxyethyl acetate 22.6
    2-ethylhexyl acetate 9.83
    1,2,4-trichlorobenzene 28.63
    4-methylpyridine 34.26
    dibutyl ether 6.66
    2,6-dimethyl-4-heptanol 3.88
    DEF 28.48
    dimethyl isosorbide 38.21
    tetrachloroethylene 38.65
    eugenol 24.02
    triacetin 25.57
    span 80 14.14
    1,4-butanediol 7.34
    1,1-dichloroethane 31.9
    2-methyl-1-pentanol 4.79
    methyl formate 71.65
    2-methyl-1-butanol 2.45
    n-decane 0.99
    butyronitrile 14.54
    3,7-dimethyl-1-octanol 5.12
    1-chlorooctane 4.3
    1-chlorotetradecane 2.46
    n-nonane 0.77
    undecane 0.85
    tert-butylcyclohexane 0.5
    cyclooctane 0.16
    cyclopentanol 6.15
    tetrahydropyran 13.79
    tert-amyl methyl ether 3.84
    2,5,8-trioxanonane 39.28
    1-hexene 1.87
    2-isopropoxyethanol 16.77
    2,2,2-trifluoroethanol 24.06
    methyl butyrate 22.8

    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