Sodium Pyrosulfite

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  • Identifiers

    CAS number
    7681-57-4

    Molecular formula
    Na2O5S2

    SMILES
    [O-]S(=O)S(=O)(=O)[O-].[Na+].[Na+]

    Safety labels

    Corrosive
    Corrosive

    Irritant
    Irritant

  • Odor profile

    Fragrance
    Odorless 85.89%
    Sulfurous 23.14%
    Pungent 18.56%
    Cooked 18.47%
    Savory 18.06%
    Garlic 14.63%
    Onion 14.47%
    Burnt 14.27%
    Roasted 13.94%
    Alliaceous 13.79%

     

    Flavor
    Bitter 60.87%
    Odorless 40.96%
    Bland 22.88%
    Nitrile 20.82%
    Formyl 19.54%
    Rotten 19.28%
    Bread crust 19.18%
    Taco 18.93%
    Roasted peanuts 18.74%
    Mousy 18.64%

     

    Odor impact est.
    Low

  • Properties

    pKa est.
    -11.32 (strong acid)

    Molecular weight
    190.11 g/mol

    Melting point expt.

    • greater than 302 °F (Decomposes) (NIOSH, 2024)
    • >302 °F (decomposes)
    • >302 °F (Decomposes)

    Boiling point

    • Decomposes (NIOSH, 2024)
    • decomposes
    • Decomposes

    Flash point

    • 100.56 ˚C est.

    Solubility expt.

    • 54 % (NIOSH, 2024)
    • Freely soluble in water, glycerol; slightly soluble in alcohol
    • Soluble in ethanol
    • 66.7 g/100 g water at 25 °C
    • Very soluble in sodium bisulfite
    • In water, 39.5 wt % at 20 °C; 41.6 wt% at 40 °C; 44.6 wt% at 60 °C ... Fairly soluble in glycerol
    • Solubility in water, g/100ml at 20 °C: 65 (good)
    • 54%

  • Synonyms

    • Sodium metabisulfite
    • 7681-57-4
    • Sodium pyrosulfite
    • Sodium disulfite
    • Disodium pyrosulfite
    • Natrii disulfis
    • Campden Tablets
    • Disodium metabisulfite
    • Natrium pyrosulfit
    • Natriummetabisulfit
    • sodium pyrosulphite
    • Sodium bisulfite anhydrous
    • Natrium metabisulfurosum
    • Sodium pyrosulfite (Na2S2O5)
    • Disodium pentaoxodisulfate
    • 4VON5FNS3C
    • INS NO.223
    • Sodium metabisulfite (e 223)
    • DTXSID0029684
    • INS-223
    • NSC-158277
    • NSC-227243
    • DISODIUM PYROSULPHITE
    • E-223
    • CHEBI:114786
    • Na(2)S(2)O(5)
    • RefChem:6239
    • DTXCID30820076
    • SODIUM METABISULFITE (NA2S2O5)
    • 231-673-0
    • Fertisilo
    • Natriumbisulfit
    • Sodium metabisulphite
    • Disulfurous acid, disodium salt
    • Disodium disulphite
    • Disodiumdisulphite
    • Pyrosulfurous acid, disodium salt
    • Na2S2O5
    • MFCD00167602
    • Sodium metabisulfite [NF]
    • Sodium metabisulfite (NF)
    • Sodium metabisulfite; sodium disulfite
    • CCRIS 3951
    • HSDB 378
    • Sodium metabisulfite (Na2-S2O5)
    • EINECS 231-673-0
    • UNII-4VON5FNS3C
    • Na2O5S2
    • AI3-51684
    • sodiummetabisulphite
    • sodium metabisuifite
    • sodium metabisuiphite
    • sodium meta bisulfite
    • sodium meta-bisulfite
    • EC 231-673-0
    • SCHEMBL8342
    • Sodium pyrosulfite (JP17)
    • CHEMBL2016976
    • SODIUM PYROSULFITE [JAN]
    • SODIUM METABISULFITE [II]
    • SODIUM METABISULFITE [MI]
    • SODIUM METABISULFITE [FCC]
    • SODIUM METABISULFITE [HSDB]
    • Sodium metabisulfite, SO2 58.5%
    • SODIUM METABISULFITE [VANDF]
    • SODIUM METABISULFITE [MART.]
    • Sodium metabisulfite A.C.S. reagent
    • SODIUM METABISULFITE [USP-RS]
    • SODIUM METABISULFITE [WHO-DD]
    • AKOS015950722
    • Disulfurous acid, sodium salt (1:2)
    • NSC 158277
    • NSC 227243
    • DA-67673
    • E223
    • SODIUM METABISULFITE [EP MONOGRAPH]
    • disodium oxido(oxo)-kappa(4)-sulfanesulfonate
    • D02054
    • Disodium oxido(oxo)-lambda~4~-sulfanesulfonate
    • F044703
    • Q284549
    • 7681-57-4

  • Applications

    Often used as a reducing agent and antioxidant in food processing and beverage applications, Sodium Pyrosulfite (CAS 7681-57-4) helps limit oxidation and browning, serving as a preservative in fruit products, wines, and other processed foods; in the paper and pulp industry it functions as a reducing agent for bleaching and decolorization of cellulose; it is also used for decolorization and stabilization of dyes during textile processing; in chemical manufacturing it can act as a reducing agent or intermediate in various syntheses; and as a chlorine scavenger in water treatment to remove residual chlorine prior to use.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 188.35
    methanol 399.88
    isopropanol 107.05
    water 104.45
    ethyl acetate 61.05
    n-propanol 102.71
    acetone 233.98
    n-butanol 80.29
    acetonitrile 111.7
    DMF 1020.65
    toluene 15.01
    isobutanol 52.96
    1,4-dioxane 137.72
    methyl acetate 95.62
    THF 185.86
    2-butanone 117.3
    n-pentanol 54.86
    sec-butanol 82.51
    n-hexane 5.74
    ethylene glycol 274.67
    NMP 565.34
    cyclohexane 21.34
    DMSO 1786.0
    n-butyl acetate 33.39
    n-octanol 42.4
    chloroform 31.62
    n-propyl acetate 35.23
    acetic acid 136.76
    dichloromethane 65.52
    cyclohexanone 101.51
    propylene glycol 110.64
    isopropyl acetate 35.54
    DMAc 619.62
    2-ethoxyethanol 194.97
    isopentanol 50.52
    n-heptane 16.19
    ethyl formate 75.07
    1,2-dichloroethane 78.81
    n-hexanol 41.9
    2-methoxyethanol 427.96
    isobutyl acetate 11.35
    tetrachloromethane 9.74
    n-pentyl acetate 31.55
    transcutol 266.81
    n-heptanol 33.19
    ethylbenzene 8.84
    MIBK 35.98
    2-propoxyethanol 114.32
    tert-butanol 90.51
    MTBE 47.21
    2-butoxyethanol 69.58
    propionic acid 79.51
    o-xylene 17.82
    formic acid 323.45
    diethyl ether 86.05
    m-xylene 11.53
    p-xylene 8.87
    chlorobenzene 12.36
    dimethyl carbonate 68.7
    n-octane 7.82
    formamide 574.01
    cyclopentanone 141.93
    2-pentanone 87.1
    anisole 29.08
    cyclopentyl methyl ether 69.55
    gamma-butyrolactone 149.76
    1-methoxy-2-propanol 226.96
    pyridine 93.32
    3-pentanone 70.3
    furfural 162.06
    n-dodecane 5.8
    diethylene glycol 193.54
    diisopropyl ether 19.34
    tert-amyl alcohol 74.72
    acetylacetone 98.7
    n-hexadecane 6.15
    acetophenone 41.8
    methyl propionate 91.02
    isopentyl acetate 19.82
    trichloroethylene 64.81
    n-nonanol 36.93
    cyclohexanol 71.95
    benzyl alcohol 45.61
    2-ethylhexanol 24.18
    isooctanol 22.0
    dipropyl ether 41.36
    1,2-dichlorobenzene 12.63
    ethyl lactate 40.89
    propylene carbonate 46.89
    n-methylformamide 413.16
    2-pentanol 59.7
    n-pentane 15.58
    1-propoxy-2-propanol 82.01
    1-methoxy-2-propyl acetate 49.29
    2-(2-methoxypropoxy) propanol 72.0
    mesitylene 9.57
    ε-caprolactone 77.49
    p-cymene 12.38
    epichlorohydrin 132.5
    1,1,1-trichloroethane 18.03
    2-aminoethanol 201.76
    morpholine-4-carbaldehyde 382.52
    sulfolane 314.05
    2,2,4-trimethylpentane 3.81
    2-methyltetrahydrofuran 94.59
    n-hexyl acetate 37.58
    isooctane 2.41
    2-(2-butoxyethoxy)ethanol 102.35
    sec-butyl acetate 18.52
    tert-butyl acetate 32.9
    decalin 4.07
    glycerin 205.67
    diglyme 182.48
    acrylic acid 94.12
    isopropyl myristate 18.92
    n-butyric acid 64.71
    acetyl acetate 30.51
    di(2-ethylhexyl) phthalate 15.85
    ethyl propionate 33.97
    nitromethane 322.48
    1,2-diethoxyethane 65.34
    benzonitrile 32.77
    trioctyl phosphate 15.9
    1-bromopropane 34.98
    gamma-valerolactone 193.71
    n-decanol 29.59
    triethyl phosphate 17.45
    4-methyl-2-pentanol 24.81
    propionitrile 69.48
    vinylene carbonate 44.37
    1,1,2-trichlorotrifluoroethane 155.6
    DMS 33.96
    cumene 6.79
    2-octanol 27.58
    2-hexanone 41.62
    octyl acetate 25.8
    limonene 21.17
    1,2-dimethoxyethane 202.98
    ethyl orthosilicate 16.23
    tributyl phosphate 15.45
    diacetone alcohol 80.69
    N,N-dimethylaniline 36.59
    acrylonitrile 104.24
    aniline 40.83
    1,3-propanediol 177.39
    bromobenzene 8.69
    dibromomethane 43.27
    1,1,2,2-tetrachloroethane 63.54
    2-methyl-cyclohexyl acetate 19.27
    tetrabutyl urea 38.97
    diisobutyl methanol 18.74
    2-phenylethanol 34.69
    styrene 11.12
    dioctyl adipate 27.85
    dimethyl sulfate 152.75
    ethyl butyrate 30.82
    methyl lactate 105.95
    butyl lactate 35.12
    diethyl carbonate 19.11
    propanediol butyl ether 80.92
    triethyl orthoformate 24.19
    p-tert-butyltoluene 12.14
    methyl 4-tert-butylbenzoate 45.75
    morpholine 208.81
    tert-butylamine 49.72
    n-dodecanol 23.9
    dimethoxymethane 273.24
    ethylene carbonate 37.65
    cyrene 80.84
    2-ethoxyethyl acetate 44.21
    2-ethylhexyl acetate 16.01
    1,2,4-trichlorobenzene 17.25
    4-methylpyridine 63.14
    dibutyl ether 29.83
    2,6-dimethyl-4-heptanol 18.74
    DEF 186.67
    dimethyl isosorbide 90.46
    tetrachloroethylene 51.82
    eugenol 54.02
    triacetin 43.98
    span 80 56.21
    1,4-butanediol 91.38
    1,1-dichloroethane 30.44
    2-methyl-1-pentanol 32.08
    methyl formate 255.25
    2-methyl-1-butanol 50.59
    n-decane 8.77
    butyronitrile 53.53
    3,7-dimethyl-1-octanol 24.45
    1-chlorooctane 16.81
    1-chlorotetradecane 8.39
    n-nonane 8.76
    undecane 7.0
    tert-butylcyclohexane 2.43
    cyclooctane 9.92
    cyclopentanol 84.07
    tetrahydropyran 83.38
    tert-amyl methyl ether 47.15
    2,5,8-trioxanonane 140.52
    1-hexene 12.55
    2-isopropoxyethanol 95.62
    2,2,2-trifluoroethanol 99.04
    methyl butyrate 46.93

    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