Sulfur Dioxide

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  • Identifiers

    CAS number
    7446-09-5

    Molecular formula
    O2S

    SMILES
    O=S=O

    Safety labels

    Compressed Gas
    Compressed Gas

    Corrosive
    Corrosive

    Acute Toxic
    Acute Toxic

    Health Hazard
    Health

  • Odor profile

    Fragrance
    Odorless 90.06%
    Pungent 31.88%
    Sharp 19.11%
    Burnt 17.82%
    Sour 15.48%
    Sulfurous 14.75%
    Radish 13.31%
    Alliaceous 10.99%
    Garlic 10.96%
    Bitter 10.86%

     

    Flavor
    Bitter 72.07%
    Odorless 47.17%
    Pungent 33.63%
    Mustard 28.94%
    Formyl 25.23%
    Sulfur 24.23%
    Rotten 22.65%
    Vinegar 21.83%
    Decomposing cabbage 19.26%
    Mousy 19.04%

     

    Odor impact est.
    High

    Odor threshold

    • Odor Threshold Low: 0.33 [ppm]. Odor Threshold High: 5.0 [ppm]. Detection odor threshold from AIHA (mean = 2.7)
    • 4.70X10-1 ppm (recognition in air, chemically pure)
    • Odor threshold: 0.1 ppm (low); 3.0 ppm (high)
    • Odor threshold: 1.1750 mg/cu m (low); 12.5000 mg/cu m (high); Irritating odor concn: 5.0 mg/cu m.
    • The odor is detectable at 0.5 ppm, although concentrations above 6 ppm have been reported to produce instantaneous mucous membrane irritation.

  • Properties

    XLogP3-AA
    0.1

    pKa est.
    0.88 (strong acid)

    Molecular weight
    64.07 g/mol

    Melting point expt.

    • -98.9 °F (EPA, 1998)
    • -75.5 °C
    • -75.48 °C
    • -104 °F

    Boiling point

    • 14 °F at 760 mmHg (EPA, 1998)
    • -10 °C
    • -10.05 °C
    • -10.00 °C. @ 760.00 mm Hg
    • 14 °F

    Flash point

    • 49.88 ˚C est.

    Solubility expt.

    • 10 % (NIOSH, 2024)
    • In water, 1.07X10+5 mg/L at 21 °C
    • Soluble in water
    • In water: 17.7% at 0 °C; 11.9% at 15 °C; 8.5% at 25 °C; 6.4% at 35 °C
    • Soluble in water ... forms sulfurous acid (H2SO3)
    • For more Solubility (Complete) data for Sulfur dioxide (7 total), please visit the HSDB record page.
    • 107 mg/mL at 21 °C
    • Solubility in water, ml/100ml at 25 °C: 8.5
    • 10%

  • Synonyms

    • sulfur dioxide
    • sulphur dioxide
    • Sulfurous anhydride
    • 7446-09-5
    • Sulfurous oxide
    • Sulfur superoxide
    • Fermenicide liquid
    • Fermenicide powder
    • Sulfur oxide (SO2)
    • Sulfurous acid anhydride
    • Schwefeldioxid
    • Siarki dwutlenek
    • Sulfur dioxide (SO2)
    • dioxidosulfur
    • Schwefeldioxyd
    • Oxosulfane oxide
    • Caswell No. 813
    • FEMA No. 3039
    • Surfur dioxide (anhydrous)
    • Fermenticide liquid
    • Schwefel(IV)-oxid
    • UN 1079
    • SULFUROXIDE
    • CCRIS 9001
    • HSDB 228
    • SO2
    • Sulfur dioxide (NF)
    • SULFUR-DIOXIDE
    • CHEBI:18422
    • 0UZA3422Q4
    • EINECS 231-195-2
    • EPA Pesticide Chemical Code 077601
    • UNII-0UZA3422Q4
    • INS NO.220
    • DTXSID6029672
    • Sulfon
    • INS-220
    • SULFUR DIOXIDE (E 220)
    • Sulfur dioxide (SO2) 10% by volume or more SO2
    • SULFUROUS ANHYDRIDE (E220)
    • Sulfur dioxide [NF]
    • E220
    • E-220
    • R-764
    • EC 231-195-2
    • SULFUR DIOXIDE (II)
    • SULFUR DIOXIDE [II]
    • SULFUR DIOXIDE (IARC)
    • SULFUR DIOXIDE [IARC]
    • Sulfur dioxide, >=99.9%
    • SULFUR DIOXIDE (MART.)
    • SULFUR DIOXIDE [MART.]
    • Sulfurdioxide
    • (SO2)
    • [SO2]
    • Schwefeldioxyd [German]
    • Siarki dwutlenek [Polish]
    • sulfonyl
    • sulfuryl
    • sulphonyl
    • sulfer dioxide
    • Dioxide, Sulfur
    • Oxosulfane oxide #
    • Anhydride, Sulfurous
    • UN1079
    • 67015-63-8
    • Sulfur dioxide [UN1079] [Poison gas]
    • Sulphur dioxide, liquified
    • SULFUR DIOXIDE [MI]
    • SULFUR DIOXIDE [FCC]
    • SULFUR DIOXIDE [FHFI]
    • SULFUR DIOXIDE [HSDB]
    • DTXCID009672
    • Sulfur dioxide, >=99.98%
    • CHEMBL1235997
    • FEMA 3039
    • InChI=1/O2S/c1-3-2
    • RAHZWNYVWXNFOC-UHFFFAOYSA-
    • SULFUR DIOXIDE, LIQUEFIED
    • SULPHUR DIOXIDE, LIQUEFIED
    • SULFUR DIOXIDE (ANHYDROUS)
    • AKOS015904447
    • USEPA/OPP Pesticide Code: 077601
    • Sulfur dioxide [UN1079] [Poison gas]
    • NS00076361
    • Q5282
    • U0147
    • U0148
    • C09306
    • D05961
    • Sulfur Dioxide (ca. 2.5% in Dichloromethane, ca. 0.5 mol/L)
    • Sulfur Dioxide (ca. 8% in Tetrahydrofuran, ca. 1.2 mol/L)

  • Applications

    Sulfur Dioxide (CAS 7446-09-5) is widely used in the food and beverage sector as a preservative and antioxidant, helping to prevent browning, spoilage, and microbial growth in products such as wine, dried fruits, and fruit juices. In the pulp and paper industry it serves as a bleaching and pulping agent (sulfite process), enabling low-severity bleaching of cellulose. In chemical manufacturing, it functions as a source of sulfite and bisulfite reagents and as a mild reducing agent in various organic syntheses, and it can be employed to generate sulfurous acid for downstream chemical transformations. These applications are typically conducted under strict process controls and in alignment with local regulations.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 196.83
    methanol 270.79
    isopropanol 172.43
    water 34.35
    ethyl acetate 73.79
    n-propanol 128.33
    acetone 214.25
    n-butanol 110.52
    acetonitrile 119.18
    DMF 816.77
    toluene 36.61
    isobutanol 85.62
    1,4-dioxane 166.66
    methyl acetate 93.48
    THF 275.4
    2-butanone 114.79
    n-pentanol 73.23
    sec-butanol 117.09
    n-hexane 20.01
    ethylene glycol 117.09
    NMP 360.9
    cyclohexane 20.95
    DMSO 756.23
    n-butyl acetate 40.92
    n-octanol 53.62
    chloroform 80.57
    n-propyl acetate 43.5
    acetic acid 120.66
    dichloromethane 94.97
    cyclohexanone 94.62
    propylene glycol 91.97
    isopropyl acetate 54.43
    DMAc 454.99
    2-ethoxyethanol 136.8
    isopentanol 81.84
    n-heptane 16.62
    ethyl formate 72.2
    1,2-dichloroethane 91.12
    n-hexanol 60.0
    2-methoxyethanol 296.24
    isobutyl acetate 24.91
    tetrachloromethane 25.99
    n-pentyl acetate 44.36
    transcutol 150.93
    n-heptanol 48.53
    ethylbenzene 21.19
    MIBK 61.32
    2-propoxyethanol 121.9
    tert-butanol 203.25
    MTBE 123.59
    2-butoxyethanol 88.07
    propionic acid 84.87
    o-xylene 34.01
    formic acid 113.86
    diethyl ether 131.69
    m-xylene 32.08
    p-xylene 25.13
    chlorobenzene 34.37
    dimethyl carbonate 83.11
    n-octane 10.2
    formamide 198.33
    cyclopentanone 155.62
    2-pentanone 99.86
    anisole 57.47
    cyclopentyl methyl ether 103.44
    gamma-butyrolactone 156.93
    1-methoxy-2-propanol 222.27
    pyridine 102.8
    3-pentanone 75.45
    furfural 144.72
    n-dodecane 9.25
    diethylene glycol 123.74
    diisopropyl ether 44.38
    tert-amyl alcohol 137.25
    acetylacetone 95.52
    n-hexadecane 9.75
    acetophenone 49.92
    methyl propionate 91.93
    isopentyl acetate 34.36
    trichloroethylene 88.75
    n-nonanol 47.3
    cyclohexanol 78.24
    benzyl alcohol 50.72
    2-ethylhexanol 33.81
    isooctanol 36.8
    dipropyl ether 56.38
    1,2-dichlorobenzene 34.38
    ethyl lactate 41.87
    propylene carbonate 68.84
    n-methylformamide 248.39
    2-pentanol 85.4
    n-pentane 30.0
    1-propoxy-2-propanol 89.98
    1-methoxy-2-propyl acetate 54.74
    2-(2-methoxypropoxy) propanol 73.07
    mesitylene 25.31
    ε-caprolactone 74.69
    p-cymene 18.48
    epichlorohydrin 139.53
    1,1,1-trichloroethane 56.59
    2-aminoethanol 137.07
    morpholine-4-carbaldehyde 254.19
    sulfolane 232.43
    2,2,4-trimethylpentane 12.13
    2-methyltetrahydrofuran 143.41
    n-hexyl acetate 53.19
    isooctane 10.53
    2-(2-butoxyethoxy)ethanol 94.13
    sec-butyl acetate 29.93
    tert-butyl acetate 63.54
    decalin 9.35
    glycerin 138.52
    diglyme 154.39
    acrylic acid 88.49
    isopropyl myristate 29.86
    n-butyric acid 81.06
    acetyl acetate 41.7
    di(2-ethylhexyl) phthalate 29.07
    ethyl propionate 47.49
    nitromethane 208.26
    1,2-diethoxyethane 66.9
    benzonitrile 43.29
    trioctyl phosphate 26.79
    1-bromopropane 65.1
    gamma-valerolactone 169.33
    n-decanol 38.37
    triethyl phosphate 27.0
    4-methyl-2-pentanol 47.96
    propionitrile 80.36
    vinylene carbonate 60.89
    1,1,2-trichlorotrifluoroethane 114.01
    DMS 44.6
    cumene 18.35
    2-octanol 42.18
    2-hexanone 53.3
    octyl acetate 38.17
    limonene 26.67
    1,2-dimethoxyethane 210.8
    ethyl orthosilicate 27.01
    tributyl phosphate 26.79
    diacetone alcohol 96.41
    N,N-dimethylaniline 60.07
    acrylonitrile 105.64
    aniline 62.47
    1,3-propanediol 142.31
    bromobenzene 29.48
    dibromomethane 73.63
    1,1,2,2-tetrachloroethane 89.6
    2-methyl-cyclohexyl acetate 29.61
    tetrabutyl urea 45.97
    diisobutyl methanol 29.17
    2-phenylethanol 42.59
    styrene 27.14
    dioctyl adipate 37.63
    dimethyl sulfate 146.68
    ethyl butyrate 35.54
    methyl lactate 86.31
    butyl lactate 42.42
    diethyl carbonate 26.28
    propanediol butyl ether 80.62
    triethyl orthoformate 31.99
    p-tert-butyltoluene 21.24
    methyl 4-tert-butylbenzoate 63.83
    morpholine 197.5
    tert-butylamine 125.54
    n-dodecanol 31.76
    dimethoxymethane 318.67
    ethylene carbonate 53.0
    cyrene 65.68
    2-ethoxyethyl acetate 54.72
    2-ethylhexyl acetate 27.67
    1,2,4-trichlorobenzene 40.11
    4-methylpyridine 94.0
    dibutyl ether 43.55
    2,6-dimethyl-4-heptanol 29.17
    DEF 163.29
    dimethyl isosorbide 92.27
    tetrachloroethylene 68.91
    eugenol 69.6
    triacetin 49.38
    span 80 67.11
    1,4-butanediol 64.43
    1,1-dichloroethane 74.58
    2-methyl-1-pentanol 52.22
    methyl formate 170.78
    2-methyl-1-butanol 76.02
    n-decane 12.68
    butyronitrile 74.45
    3,7-dimethyl-1-octanol 38.27
    1-chlorooctane 28.37
    1-chlorotetradecane 16.41
    n-nonane 12.59
    undecane 10.64
    tert-butylcyclohexane 9.87
    cyclooctane 9.56
    cyclopentanol 108.32
    tetrahydropyran 119.46
    tert-amyl methyl ether 96.83
    2,5,8-trioxanonane 120.1
    1-hexene 39.03
    2-isopropoxyethanol 90.43
    2,2,2-trifluoroethanol 68.0
    methyl butyrate 57.83

    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