Hydrogen Cyanide

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  • Identifiers

    CAS number
    74-90-8

    Molecular formula
    CHN

    SMILES
    C#N

    Safety labels

    Flammable
    Flammable

    Acute Toxic
    Acute Toxic

    Health Hazard
    Health

    Environmental Hazard
    Environmental

  • Odor profile

    Odorless 46.39%
    Pungent 28.1%
    Bitter 17.38%
    Sulfurous 17.27%
    Sharp 16.9%
    Fishy 16.22%
    Almond 14.9%
    Burnt 14.71%
    Floral 14.56%
    Garlic 14.39%

    Scent© AI

    Odor threshold

    • Odor Threshold Low: 2.0 [mmHg]. Odor Threshold High: 10.0 [mmHg]
    • Approximately 60 to 70% of the population can detect the bitter almond odor of hydrogen cyanide. The odor threshold for those sensitive to the odor is estimated to be 1 to 5 ppm in the air. However, even at high toxic concentrations, up to 20% of all individuals are genetically unable to smell hydrogen cyanide.
    • Detection in air of hydrogen cyanide of an unspecified purity or grade: 1X10-3 mg/L.
    • High odor threshold was 5 mg/cu m; Low odor threshold was 0.9 mg/cu m.

  • Properties

    XLogP3-AA
    0.1

    pKa est.
    8.88 (weak base)

    Molecular weight
    27.025 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra fast

    Melting point expt.

    • 7 °F (96%) (NIOSH, 2024)
    • -13.28 °C
    • 5.00 °C. @ 0.00 mm Hg
    • 7 °F (96%)

    Boiling point

    • 78 °F at 760 mmHg (96%) (NIOSH, 2024)
    • 25.63 °C
    • 79.00 °C. @ 0.00 mm Hg
    • 78 °F (96%)

    Flash point est.
    -25.31 ˚C

    Flash point expt.

    • 0 °F (96%) (NIOSH, 2024)
    • 0 °F (-18 °C) (Closed cup)
    • 0 °F (96%)

    Solubility expt.

    • Miscible (NIOSH, 2024)
    • Miscible with water
    • Miscible with ethanol, ethyl ether
    • Miscible with alcohol; slightly soluble in ether
    • 1.00E+06 mg/L @ 25 °C (exp)
    • Miscible

  • Synonyms

    • hydrogen cyanide
    • hydrocyanic acid
    • Formonitrile
    • Prussic acid
    • Cyanwasserstoff
    • Blausaeure
    • Formic anammonide
    • Zaclondiscoids
    • Evercyn
    • Cyclon
    • 74-90-8
    • Cyclone B
    • Aero Liquid HCN
    • Agent AC
    • Cyaanwaterstof
    • Blauwzuur
    • Cyjanowodor
    • Acido cianidrico
    • Acide cyanhydrique
    • methanenitrile
    • Caswell No. 483
    • Graphitic Carbon Nitride
    • Hydrogen cyanide [ISO]
    • hydridonitridocarbon
    • RCRA waste number P063
    • Blausaeure [German]
    • Carbon hydride nitride (CHN)
    • HSDB 165
    • 143334-20-7
    • HCN
    • UN 1051
    • hydrogen(nitridocarbonate)
    • EINECS 200-821-6
    • [CHN]
    • UNII-2WTB3V159F
    • AC [Cyanide]
    • EPA Pesticide Chemical Code 045801
    • AI3-31100-X
    • BRN 1718793
    • 2WTB3V159F
    • CHEBI:18407
    • Acide cyanhydrique [ISO-French]
    • Carbon nitride (C3N4)
    • HYDROCYANICUM ACIDUM
    • Zyklon B
    • CHEMBL183419
    • DTXSID9024148
    • EC 200-821-6
    • AC (CHEMICAL WARFARE AGENT)
    • AC (Cyanide)
    • Blausaeure (German)
    • (CHN)
    • Blauwzuur [Dutch]
    • Cyjanowodor [Polish]
    • Acide cyanhydrique (ISO-French)
    • Cyaanwaterstof [Dutch]
    • Cyanwasserstoff [German]
    • Acido cianidrico [Italian]
    • Acid, Hydrocyanic
    • Cyanide, Hydrogen
    • Acide cyanhydrique [French]
    • NA1613
    • UN1051
    • UN1613
    • UN1614
    • UN3294
    • RCRA waste no. P063
    • Zootic acid
    • Nitrilomethane #
    • Prussic acid, anhydrous, stabilized
    • Carbon hydride nitride
    • Hydrocyanic acid, anhydrous, stabilized
    • Hydrogen cyanide, anhydrous, stabilized
    • Prussic acid, unstabilized
    • UN 1613 (Salt/Mix)
    • UN 1614 (Salt/Mix)
    • HYDROGEN CYANIDE [MI]
    • Hydrocyanic acid (prussic), unstabilized [Forbidden]
    • DTXCID004148
    • HYDROGEN CYANIDE [HSDB]
    • HYDROGEN CYANIDE [WHO-DD]
    • HYDROCYANICUM ACIDUM [HPUS]
    • TFA33420
    • BDBM50152968
    • Hydrocyanic acid, anhydrous, stabilized, absorbed in a porous inert material
    • Hydrogen cyanide, anhydrous, stabilized, absorbed in a porous inert material
    • Prussic acid, anhydrous, stabilized, absorbed in a porous inert material
    • NA 1051
    • Hydrocyanic acid (prussic), unstabilized
    • CHN
    • CS-0621744
    • Hydrogen cyanide, stabilized with <3% water
    • NS00077168
    • C01326
    • Q3416481
    • Graphitic carbon nitride, 99%, length: 1 - 10 mum
    • hydridonitridocarbonhydrogen(nitridocarbonate)methanenitrile
    • Hydrogen cyanide, stabilized with <3% water [UN1051] [Poison]
    • Hydrogen cyanide, stabilized, with <3% water and absorbed in a porous inert material
    • 200-821-6
    • Hydrogen cyanide, stabilized, with <3% water and absorbed in a porous inert material [UN1614] [Poison]

  • Applications

    Hydrogen cyanide (HCN, CAS 74-90-8) is used primarily as an industrial feedstock: enabling hydrocyanation/cyanation to make adiponitrile for nylon 6,6; forming acetone cyanohydrin as a precursor to methyl methacrylate (and PMMA); participating in routes to DL‑methionine for animal nutrition; supporting production of sodium and potassium cyanide for gold hydrometallurgy and electroplating; and serving as a building block for pharmaceutical and agrochemical intermediates (e.g., Strecker synthesis of amino acids) and for introducing nitrile/cyanohydrin functionality in laboratory synthesis; owing to its extreme toxicity and volatility, its use, transport, and storage are tightly regulated with closed systems, continuous monitoring, and compliant treatment of off-gases and effluents; historical fumigant use has largely been discontinued, and modern applications emphasize risk control, environmental stewardship, and regulatory compliance.

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 103.56
    methanol 226.08
    isopropanol 55.61
    water 95.08
    ethyl acetate 75.09
    n-propanol 63.55
    acetone 188.58
    n-butanol 40.98
    acetonitrile 264.65
    DMF 578.67
    toluene 17.41
    isobutanol 42.46
    1,4-dioxane 140.68
    methyl acetate 150.8
    THF 99.68
    2-butanone 101.93
    n-pentanol 25.66
    sec-butanol 42.59
    n-hexane 3.77
    ethylene glycol 144.11
    NMP 384.9
    cyclohexane 12.13
    DMSO 363.14
    n-butyl acetate 37.0
    n-octanol 14.78
    chloroform 150.37
    n-propyl acetate 35.41
    acetic acid 374.66
    dichloromethane 176.85
    cyclohexanone 101.2
    propylene glycol 64.33
    isopropyl acetate 28.38
    DMAc 420.81
    2-ethoxyethanol 73.3
    isopentanol 24.7
    n-heptane 6.37
    ethyl formate 77.8
    1,2-dichloroethane 95.78
    n-hexanol 23.11
    2-methoxyethanol 162.94
    isobutyl acetate 17.58
    tetrachloromethane 38.7
    n-pentyl acetate 19.6
    transcutol 139.8
    n-heptanol 12.73
    ethylbenzene 6.95
    MIBK 20.15
    2-propoxyethanol 56.29
    tert-butanol 53.57
    MTBE 36.73
    2-butoxyethanol 31.32
    propionic acid 155.43
    o-xylene 17.03
    formic acid 363.73
    diethyl ether 49.52
    m-xylene 10.53
    p-xylene 13.34
    chlorobenzene 41.35
    dimethyl carbonate 55.73
    n-octane 2.26
    formamide 383.09
    cyclopentanone 123.83
    2-pentanone 49.14
    anisole 30.15
    cyclopentyl methyl ether 44.3
    gamma-butyrolactone 166.76
    1-methoxy-2-propanol 73.49
    pyridine 143.45
    3-pentanone 61.82
    furfural 194.23
    n-dodecane 1.9
    diethylene glycol 86.94
    diisopropyl ether 9.56
    tert-amyl alcohol 41.72
    acetylacetone 70.68
    n-hexadecane 2.08
    acetophenone 38.21
    methyl propionate 87.88
    isopentyl acetate 23.75
    trichloroethylene 196.15
    n-nonanol 12.41
    cyclohexanol 44.44
    benzyl alcohol 31.26
    2-ethylhexanol 14.98
    isooctanol 9.96
    dipropyl ether 25.88
    1,2-dichlorobenzene 40.12
    ethyl lactate 27.54
    propylene carbonate 76.73
    n-methylformamide 302.51
    2-pentanol 22.97
    n-pentane 5.47
    1-propoxy-2-propanol 37.29
    1-methoxy-2-propyl acetate 37.22
    2-(2-methoxypropoxy) propanol 33.95
    mesitylene 7.34
    ε-caprolactone 80.57
    p-cymene 9.54
    epichlorohydrin 116.03
    1,1,1-trichloroethane 82.48
    2-aminoethanol 112.02
    morpholine-4-carbaldehyde 264.79
    sulfolane 188.98
    2,2,4-trimethylpentane 3.09
    2-methyltetrahydrofuran 74.24
    n-hexyl acetate 25.97
    isooctane 1.44
    2-(2-butoxyethoxy)ethanol 41.22
    sec-butyl acetate 16.9
    tert-butyl acetate 24.62
    decalin 3.29
    glycerin 125.77
    diglyme 98.39
    acrylic acid 211.3
    isopropyl myristate 9.89
    n-butyric acid 90.25
    acetyl acetate 61.51
    di(2-ethylhexyl) phthalate 13.33
    ethyl propionate 33.5
    nitromethane 586.92
    1,2-diethoxyethane 38.27
    benzonitrile 58.11
    trioctyl phosphate 9.86
    1-bromopropane 38.23
    gamma-valerolactone 160.45
    n-decanol 9.48
    triethyl phosphate 17.56
    4-methyl-2-pentanol 9.84
    propionitrile 102.9
    vinylene carbonate 88.68
    1,1,2-trichlorotrifluoroethane 171.93
    DMS 48.4
    cumene 6.08
    2-octanol 8.18
    2-hexanone 28.16
    octyl acetate 15.02
    limonene 15.49
    1,2-dimethoxyethane 100.14
    ethyl orthosilicate 15.82
    tributyl phosphate 12.4
    diacetone alcohol 36.21
    N,N-dimethylaniline 25.83
    acrylonitrile 182.4
    aniline 48.39
    1,3-propanediol 88.49
    bromobenzene 36.48
    dibromomethane 91.49
    1,1,2,2-tetrachloroethane 124.83
    2-methyl-cyclohexyl acetate 18.32
    tetrabutyl urea 21.48
    diisobutyl methanol 8.61
    2-phenylethanol 24.36
    styrene 12.81
    dioctyl adipate 19.51
    dimethyl sulfate 117.64
    ethyl butyrate 32.24
    methyl lactate 58.97
    butyl lactate 19.94
    diethyl carbonate 25.11
    propanediol butyl ether 33.44
    triethyl orthoformate 22.25
    p-tert-butyltoluene 8.21
    methyl 4-tert-butylbenzoate 27.97
    morpholine 146.19
    tert-butylamine 31.27
    n-dodecanol 7.91
    dimethoxymethane 107.91
    ethylene carbonate 64.9
    cyrene 40.99
    2-ethoxyethyl acetate 37.36
    2-ethylhexyl acetate 19.78
    1,2,4-trichlorobenzene 58.59
    4-methylpyridine 92.52
    dibutyl ether 15.25
    2,6-dimethyl-4-heptanol 8.61
    DEF 121.85
    dimethyl isosorbide 48.8
    tetrachloroethylene 109.37
    eugenol 31.05
    triacetin 41.63
    span 80 29.56
    1,4-butanediol 40.85
    1,1-dichloroethane 80.29
    2-methyl-1-pentanol 18.84
    methyl formate 206.05
    2-methyl-1-butanol 30.37
    n-decane 2.84
    butyronitrile 62.41
    3,7-dimethyl-1-octanol 12.6
    1-chlorooctane 9.72
    1-chlorotetradecane 4.39
    n-nonane 2.91
    undecane 2.21
    tert-butylcyclohexane 2.74
    cyclooctane 2.94
    cyclopentanol 59.95
    tetrahydropyran 71.58
    tert-amyl methyl ether 28.6
    2,5,8-trioxanonane 69.1
    1-hexene 10.1
    2-isopropoxyethanol 38.8
    2,2,2-trifluoroethanol 193.88
    methyl butyrate 45.56

    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
Almond 8013-76-1 Prunus dulcis (Miller) D.A. Webb (P. amygdalus Batsch, P. communis L.) 3.0%
Apricot kernel 68650-44-2 Prunus armeniaca L., fam. Rosaceae 3.0%