Nitrous Acid

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  • Identifiers

    CAS number
    7782-77-6

    Molecular formula
    HNO2

    SMILES
    N(=O)O

    Safety labels

    Corrosive
    Corrosive

    Acute Toxic
    Acute Toxic

    Environmental Hazard
    Environmental

  • Odor profile

    Fragrance
    Odorless 76.08%
    Sharp 33.48%
    Sour 31.15%
    Pungent 30.93%
    Fruity 29.5%
    Cheesy 22.65%
    Fermented 19.54%
    Ethereal 19.02%
    Sweaty 16.49%
    Burnt 16.33%

     

    Flavor
    Odorless 56.33%
    Pungent 45.85%
    Vinegar 37.44%
    Bitter 31.09%
    Mustard 29.81%
    Sour 28.94%
    Formyl 26.85%
    Soy 21.62%
    Mousy 21.57%
    Rotten 20.91%

     

    Odor impact est.
    Low

  • Properties

    XLogP3-AA
    -0.3

    pKa est.
    8.0 (weak base)

    Molecular weight
    47.014 g/mol

    Melting point expt.

    • 271 undefined

    Boiling point

    • 320 undefined

    Flash point

    • 73.25 ˚C est.

    Solubility expt.

    • 820g/L

  • Synonyms

    • NITROUS ACID
    • Nitrosyl hydroxide
    • 7782-77-6
    • HNO2
    • Kyselina dusite
    • dioxonitric acid
    • hydroxidooxidonitrogen
    • CHEBI:25567
    • Acid, Nitrous
    • UNII-T2I5UM75DN
    • EINECS 231-963-7
    • T2I5UM75DN
    • HONO
    • HSDB 7801
    • hydrogen dioxonitrate(1-)
    • DTXSID7064813
    • (NO(OH))
    • [NO(OH)]
    • Kyselina dusite [Czech]
    • Nitrogen dioxide ion
    • Nitrous acid, trans
    • Nitrogen peroxide ion
    • NITROUS ACID [MI]
    • CHEMBL1161681
    • DTXCID4048014
    • BLNWTAHYTCHDJH-UHFFFAOYSA-N
    • BDBM50147619
    • DB09112
    • DB-255799
    • NS00076377
    • C00088
    • Q207895
    • Q211891
    • 231-963-7

  • Applications

    Nitrous Acid (CAS 7782-77-6) is used as a nitrosating and diazotizing reagent in organic synthesis, typically generated in situ from nitrite under acidic conditions. In industry, its applications include: 1) diazotization of aromatic amines to form diazonium salts for azo dye and pigment production used in textiles, coatings, and printing inks; 2) synthesis of diazonium intermediates for surface modification and grafting onto polymers and materials; 3) nitrosation of amines and related substrates to give N-nitroso compounds, which serve as intermediates in pharmaceutical and fragrance chemistry under controlled conditions; 4) participation in selective nitrosation steps within fine chemical manufacturing; 5) analytical use in nitrite/nitrosating species quantification in environmental and industrial samples through nitrosation-based assays.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 51.06
    methanol 112.44
    isopropanol 36.41
    water 268.97
    ethyl acetate 12.72
    n-propanol 32.09
    acetone 48.42
    n-butanol 20.56
    acetonitrile 28.78
    DMF 655.24
    toluene 4.53
    isobutanol 23.46
    1,4-dioxane 71.15
    methyl acetate 27.61
    THF 52.94
    2-butanone 22.25
    n-pentanol 15.5
    sec-butanol 21.59
    n-hexane 1.55
    ethylene glycol 91.65
    NMP 207.97
    cyclohexane 1.61
    DMSO 296.74
    n-butyl acetate 7.61
    n-octanol 7.89
    chloroform 3.77
    n-propyl acetate 11.4
    acetic acid 59.33
    dichloromethane 7.85
    cyclohexanone 22.41
    propylene glycol 59.86
    isopropyl acetate 8.15
    DMAc 372.62
    2-ethoxyethanol 73.46
    isopentanol 17.37
    n-heptane 1.31
    ethyl formate 31.89
    1,2-dichloroethane 8.55
    n-hexanol 7.56
    2-methoxyethanol 140.09
    isobutyl acetate 6.63
    tetrachloromethane 1.33
    n-pentyl acetate 7.25
    transcutol 73.48
    n-heptanol 6.89
    ethylbenzene 2.9
    MIBK 9.57
    2-propoxyethanol 40.35
    tert-butanol 38.49
    MTBE 17.87
    2-butoxyethanol 28.1
    propionic acid 36.28
    o-xylene 6.31
    formic acid 118.07
    diethyl ether 14.22
    m-xylene 4.23
    p-xylene 3.91
    chlorobenzene 2.89
    dimethyl carbonate 40.2
    n-octane 0.63
    formamide 153.79
    cyclopentanone 32.18
    2-pentanone 13.91
    anisole 15.82
    cyclopentyl methyl ether 18.52
    gamma-butyrolactone 51.78
    1-methoxy-2-propanol 77.14
    pyridine 24.36
    3-pentanone 12.99
    furfural 70.09
    n-dodecane 0.71
    diethylene glycol 62.12
    diisopropyl ether 3.97
    tert-amyl alcohol 25.77
    acetylacetone 19.41
    n-hexadecane 0.74
    acetophenone 15.39
    methyl propionate 23.76
    isopentyl acetate 6.58
    trichloroethylene 8.16
    n-nonanol 7.38
    cyclohexanol 14.06
    benzyl alcohol 17.04
    2-ethylhexanol 4.79
    isooctanol 5.64
    dipropyl ether 9.1
    1,2-dichlorobenzene 3.23
    ethyl lactate 19.93
    propylene carbonate 24.56
    n-methylformamide 184.2
    2-pentanol 11.1
    n-pentane 1.75
    1-propoxy-2-propanol 24.73
    1-methoxy-2-propyl acetate 15.2
    2-(2-methoxypropoxy) propanol 36.99
    mesitylene 3.38
    ε-caprolactone 23.66
    p-cymene 2.75
    epichlorohydrin 36.45
    1,1,1-trichloroethane 2.95
    2-aminoethanol 87.24
    morpholine-4-carbaldehyde 232.82
    sulfolane 79.19
    2,2,4-trimethylpentane 1.06
    2-methyltetrahydrofuran 22.67
    n-hexyl acetate 9.07
    isooctane 0.71
    2-(2-butoxyethoxy)ethanol 39.13
    sec-butyl acetate 6.16
    tert-butyl acetate 9.06
    decalin 1.09
    glycerin 106.34
    diglyme 79.22
    acrylic acid 51.17
    isopropyl myristate 4.89
    n-butyric acid 21.78
    acetyl acetate 8.44
    di(2-ethylhexyl) phthalate 8.64
    ethyl propionate 12.8
    nitromethane 116.37
    1,2-diethoxyethane 16.55
    benzonitrile 11.74
    trioctyl phosphate 5.97
    1-bromopropane 3.82
    gamma-valerolactone 90.27
    n-decanol 6.11
    triethyl phosphate 7.78
    4-methyl-2-pentanol 7.11
    propionitrile 18.17
    vinylene carbonate 29.9
    1,1,2-trichlorotrifluoroethane 48.55
    DMS 15.36
    cumene 2.84
    2-octanol 4.67
    2-hexanone 10.76
    octyl acetate 6.97
    limonene 3.6
    1,2-dimethoxyethane 126.14
    ethyl orthosilicate 7.27
    tributyl phosphate 6.96
    diacetone alcohol 21.44
    N,N-dimethylaniline 19.72
    acrylonitrile 31.85
    aniline 14.24
    1,3-propanediol 65.69
    bromobenzene 1.74
    dibromomethane 3.9
    1,1,2,2-tetrachloroethane 8.38
    2-methyl-cyclohexyl acetate 6.61
    tetrabutyl urea 14.64
    diisobutyl methanol 4.12
    2-phenylethanol 9.09
    styrene 3.55
    dioctyl adipate 9.47
    dimethyl sulfate 76.78
    ethyl butyrate 8.54
    methyl lactate 45.42
    butyl lactate 13.85
    diethyl carbonate 7.86
    propanediol butyl ether 32.23
    triethyl orthoformate 9.46
    p-tert-butyltoluene 2.85
    methyl 4-tert-butylbenzoate 19.58
    morpholine 86.69
    tert-butylamine 18.7
    n-dodecanol 5.14
    dimethoxymethane 124.98
    ethylene carbonate 24.44
    cyrene 38.41
    2-ethoxyethyl acetate 13.63
    2-ethylhexyl acetate 5.05
    1,2,4-trichlorobenzene 4.33
    4-methylpyridine 26.0
    dibutyl ether 6.38
    2,6-dimethyl-4-heptanol 4.12
    DEF 58.54
    dimethyl isosorbide 37.81
    tetrachloroethylene 6.11
    eugenol 25.19
    triacetin 16.87
    span 80 23.52
    1,4-butanediol 37.27
    1,1-dichloroethane 4.62
    2-methyl-1-pentanol 11.76
    methyl formate 133.83
    2-methyl-1-butanol 17.34
    n-decane 0.91
    butyronitrile 14.38
    3,7-dimethyl-1-octanol 6.28
    1-chlorooctane 2.11
    1-chlorotetradecane 1.43
    n-nonane 0.85
    undecane 0.78
    tert-butylcyclohexane 1.04
    cyclooctane 0.84
    cyclopentanol 20.22
    tetrahydropyran 21.37
    tert-amyl methyl ether 13.77
    2,5,8-trioxanonane 63.42
    1-hexene 3.32
    2-isopropoxyethanol 38.17
    2,2,2-trifluoroethanol 51.09
    methyl butyrate 18.39

    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